Planetary Health: Protecting Nature to Protect Ourselves 9781610919661

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Planetary Health: Protecting Nature to Protect Ourselves

Planetary Health: Protecting Nature to Protect Ourselves

Edited by Samuel Myers and Howard Frumkin

Copyright © 2020 Samuel Myers and Howard Frumkin All rights reserved under International and Pan-American Copyright Conventions. No part of this book may be reproduced in any form or by any means without permission in writing from the publisher: Island Press, 2000 M St., NW, Suite 650 Washington, DC 20036. DOI: https://doi.org/10.5822/978-1-61091-966-1 Library of Congress Control Number: 2019955657 All Island Press books are printed on environmentally responsible materials. Manufactured in the United States of America 10 9 8 7 6 5 4 3 2 1 Keywords: biodiversity loss, climate change, climate migration, EcoHealth, ecological economics, energy and health, environmental change, environmental health, food and nutrition, global health, infectious disease, mental health, noncommunicable diseases, One Health, planetary boundaries, pollution, regenerative agriculture, sustainability, toxic exposures, well-being

Dedication For our children Sophie and Lucy, Gabe and Amara With boundless love and hope

Contents List of Tables and Boxes xi Preface: A Note on Covid-19 xiii Acknowledgmentsxv Part 1: Foundations

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  1. An Introduction to Planetary Health (Myers, Frumkin).........................................3   2. Assembling Planetary Health: Histories of the Future (Dunk, Anderson)............17   3. Population, Consumption, Equity, and Rights (Engelman, Bongaarts, Patterson)...............................................................................................................37   4. A Changing Planet.................................................................................................71 • Climate Change (Field)......................................................................................72 • Biogeochemical Cycles (Tilman)........................................................................75 • Changes in Land Use and Land Cover (DeFries)...............................................79 • Arable Land and Soil (Montgomery).................................................................85 • Water Scarcity (Gleick).......................................................................................89 • Biodiversity Loss (Tilman, Frumkin)..................................................................94 • Pollution (Landrigan).........................................................................................97

Part 2: The Health of Populations

111

  5. Food and Nutrition on a Rapidly Changing Planet (Myers)...............................113   6. Planetary Health and Infectious Disease (Ostfeld, Keesing)...............................141   7. Global Environmental Change and Noncommunicable Disease Risks (Frumkin, Haines)................................................................................................165   8. Environmental Change, Migration, Conflict, and Health (Risi, Kihato, Lorenzen, Frumkin).............................................................................................189

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  9. Mental Health on a Changing Planet (Clayton).................................................221 10. Climate Change and Human Health (Frumkin).................................................245 11. Happiness on a Healthier Planet (Helliwell, Hall)...............................................261

Part 3: Pivoting from Threat to Opportunity

283

12. Energy and Planetary Health (Pillarisetti, Smith)...............................................285 13. Urban Places and Planetary Health (Diez Roux, Lein, Dronova, Rodríguez, Henson, Sarmiento).............................................................................................325 14. Controlling Toxic Exposures (Landrigan, Collins, Myers)..................................359 15. A New Economics for Planetary Health (Evison, Bickersteth)............................387 16. The Business of Planetary Health: From Economic Theory to Policy and Practice (Evison, Bickersteth).......................................................................425

Part 4: Saving Ourselves, Saving Our Planet

451

17. Planetary Health Ethics (Foster, Cole, Petrikova, Farlow, Frumkin)...................453 18. A Bright Future for Planetary Health (Myers, Frumkin)......................................475

Afterword: Coronavirus and Planetary Health 487 Index497 About the Editors 513

List of Tables Table 4.1: Global Water Stocks by Volume (in Thousands of Cubic Kilometers) and as a Percentage of Saltwater and Freshwater Stocks   90 Table 4.2: Global Withdrawals of Water by Sector, 2010, in Cubic Kilometers per Year and as a Percentage of Total Freshwater Withdrawals   93 Table 6.1: Categories of Infectious Diseases of Humans   143 Table 8.1: International Emigration Sources and Immigration Destinations as a Percentage of Population, World Regions (2017)   196 Table 15.1: Economic, Pollution, and Natural Resource Use Statistics Then and Now  388 Table 15.2: The Effect of Discounting in Multiyear Valuation   418 Table 16.1: Pros and Cons of Different Policy Options for Planetary Health   431 Table 18.1: Criteria for Quality Visions of a Sustainable Future   481

List of Boxes Box 3.1: Why Family Planning?   57 Robert Engelman, John Bongaarts, and Kristen P. Patterson Box 3.2: A Family Planning Case Study: Pakistan and Bangladesh   59 John Bongaarts Box 3.3: Building Resilience through a Holistic Population, Health, and Environment Approach  62 Kristen P. Patterson Box 4.1: Water Withdrawals, Consumptive Use, and Nonconsumptive Use   92 Peter Gleick Box 5.1: Malnutrition in All Its Forms   115 Samuel Myers Box 5.2: How CO2 Emissions Are Making Our Food Less Healthy   122 Matthew Smith and Samuel Myers Box 6.1: Terms and Definitions   142 Richard S. Ostfeld and Felicia Keesing Box 8.1: A Glossary of Displacement Terms   198 Lauren Herzer Risi, Caroline Kihato, Rebecca Lorenzen, and Howard Frumkin xi

xii  List of Tables and Boxes

Box 8.2: A Glossary of Conflict Terms   203 Lauren Herzer Risi, Caroline Kihato, Rebecca Lorenzen, and Howard Frumkin Box 8.3: Women’s and Children’s Health in Refugee Camps   209 Sarah Barnes Box 11.1: Six Conceptual Advantages of Subjective Self-Assessment over Composite Measures of Wellbeing   266 John Helliwell and Jon Hall Box 12.1: Subsidy to Social Investment in India: A Health Intervention   294 Kirk R. Smith and Ajay Pillarisetti Box 12.2: The Environmental Health Dimensions of Oil and Gas Development   302 Lee Ann Hill and Seth B. C. Shonkoff Box 14.1: Recent Examples of Chemicals Introduced into Commerce and the Environment with Little or No Premarket Evaluation   372 Box 14.2: Twelve Principles of Green Chemistry   380 Box 18.1: Ten Ways to Save the World   477

PREFACE A Note on Covid-19 Sometime toward the end of 2019, after this book was already in final copy-editing, life’s smallest entity, a virus—SARS-CoV-2—mutated and brought the world to its knees. The mutations allowed this RNA virus to move from its primary host—most likely a bat—into human populations and from there rapidly cause a devastating loss of lives and livelihoods that is still unfolding at the time of this writing. While this book was written prior to the Covid-19 pandemic, the themes it explores have never been more relevant. As it happens, Covid-19 is a prototypical planetary health story: the virus’s origin is related to our interactions with nature and wildlife, our food system, and changes in demography and technology; lessons we are learning about controlling the pandemic underscore the importance of systems thinking, the need for collective action, and the promise of rapid global behavior change; and this global pause presents an unprecedented opportunity to chart a new course. At the end of this book, we have written an epilogue exploring the Covid-19 pandemic as a planetary health problem and emphasizing the extent to which it illustrates many of the themes that run through this book. If you are impatient to put today’s events into the context of planetary health, we invite you to skip to the end, read the epilogue, and then come back to the beginning. Otherwise, the epilogue is best read last, as a summary of many of this book’s themes and an opportunity to make sense of the extraordinary moment we find ourselves in. Either way, we wish you good health and solace in these times of upheaval. Samuel Myers and Howard Frumkin

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Acknowledgments Many book acknowledgments begin with thanks to professional colleagues and end with the authors’ or editors’ spouses. We are reversing that custom. Kelsey (Sam) and Joanne (Howie) come first. We appreciate, more than we can say, their support for each of us as we worked on this book, from our first long meeting in Crested Butte (on time pilfered from a joint family holiday) to the many evenings and weekends since then. Even more than that, we appreciate their companionship and love on our life journeys. Kelsey is a climate activist, Joanne a global health journalist—and both are values-driven, dedicated, highly effective, compassionate women. We are both very lucky men, and we know it. We both trained in medicine and public health, but our intellectual journeys have taken us far afield from there—from ecology to agronomy, from urban and transportation planning to earth science. No one makes such journeys alone. Innumerable friends and colleagues have taught us and guided us along the way, helping us to avoid (all but a few!) embarrassing errors as we’ve striven to knit together insights from diverse fields while avoiding being dilettantes. We cannot name you all here, but you know who you are. Any residual errors are, of course, solely our responsibility. We thank the extended Planetary Health family, a vibrant and fast-growing network in every corner of the globe. Coming from diverse backgrounds, disciplines, and institutional settings, we are united by a commitment to protecting people and protecting our planet. At meetings of the Planetary Health Alliance, in private conversations, while reading your papers, you have contributed enormously to our understanding of the issues addressed in this book. We thank the chapter authors in this book. We were heavy-handed editors, in an effort to achieve a consistent vision and voice throughout; without exception, the authors accepted our editorial bombing runs with grace and good cheer. They put enormous time and effort into their chapters, we are truly proud of what they produced, and we are deeply grateful to them all. We thank the team in Boston that helped in so many ways to bring this book to fruition. Emma Pollack, a graduate student in sustainability, health, and the global xv

xvi  Acknowledgments

environment at the Harvard T.H. Chan School of Public Health, took the initiative to approach us about working on the book, and work she did—doing anything that needed doing, from proofreading to formatting to checking references to managing illustrations. The team at the Planetary Health Alliance—Amalia Almada, Perri Sheinbaum, Erika Veidis, and Max Zimberg—provided invaluable direct and indirect support as well. We thank the Winslow Foundation, which provided funding to support the preparation of this book, and the Rockefeller Foundation, which supported the Planetary Health Alliance (including Sam’s time) during the 2 years we worked on the book. We thank the good people at Island Press. In the 35 years since its founding, this remarkable nonprofit publisher—whose tagline is “solutions that inspire change,” precisely the spirit that animates our work and this book—has produced one of the most important bodies of environmental books anywhere. It’s an honor for us to be on the same author roster with the likes of Gretchen Daily and Sylvia Earle, Paul Ehrlich and Jan Gehl, Jaime Lerner and Ian McHarg, David Orr and E.O. Wilson. Kudos to president David Miller and a special shout-out to our editor, Emily Turner, a model of good judgment, professionalism, dedication, and—critically for any author or editor—judicious patience. Finally, we thank the students who will read this book. We don’t know you, but every line in this book has been written and edited with you in mind. We hope this book piques your curiosity, fortifies your inner systems thinker, nourishes your sense of hope, and reinforces your drive to get out there and heal our planet. We need you!

Part 1 Foundations

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1 An Introduction to Planetary Health Samuel Myers and Howard Frumkin

It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, . . it was the season of Light, it was the season of Darkness, it was the spring of hope, it was the winter of despair. —Charles Dickens, A Tale of Two Cities

By many metrics, there has never been a better time to be a human being. Indeed, the past 70 years have seen almost unimaginable improvements in global human wellbeing. Between 1940 and 2015 the percentage of adults around the world who could read and write doubled, from 42% to 86%.1 In 1950, there were 1.6 billion people living in extreme poverty and 924 million people not in extreme poverty. By 2015, there were 733 million people living in extreme poverty and 6.6 billion people not living in extreme poverty.2 In other words, in 65 years the percentage of the world’s people living in extreme poverty dropped from 63% to 10% despite a near tripling of the global population. In 1950, global life expectancy was 46 years. Sixty-five years later, it was 72.3 And during that same period, child mortality dropped from 225 per 1,000 to 45 per 1,000 (Figure 1.1).4 These are unprecedented achievements in human history. But there may never have been a worse time for the rest of the biosphere, at least since human beings began walking the planet. On March 17, 2019, a male Cuvier’s beaked whale washed up in the Philippines dead. It was still immature, and, wondering what *This chapter is based in part on a previous article by Samuel Myers: Planetary health: protecting human health on a rapidly changing planet. Lancet 2017;390(10114):2860-2868.

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Figure 1.1 Measures of human development over time reveal extraordinary improvements over the twentieth century in (a) literacy, (b) wealth, (c) child survival, and (d) life expectancy. Sources: Panel A: Our World in Data (https://ourworldindata.org/literacy), Creative Commons, license CC BY 4.0 Panel B: Our World in Data (https://ourworldindata.org/extreme-poverty), Creative Commons, license CC BY 4.0 Panel C: Our World in Data (https://ourworldindata.org/child-mortality), Creative Commons, license CC BY 4.0 Panel D: Our World in Data (https://ourworldindata.org/life-expectancy), Creative Commons, license CC BY 4.0

An Introduction to Planetary Health  5

could have killed such a magnificent creature capable of diving to depths of nearly 3,000 meters and normally living up to 60 years, scientists performed a necropsy. Inside the whale’s stomach and intestines, they found 88 pounds of plastic garbage. As of 2015, the inhabitants of 192 coastal countries are responsible for dumping roughly 8 million metric tons of plastic waste into the world’s oceans every year.5 The same extraordinary scientific and technological developments that have pulled humanity out of poverty, increased our life expectancies, and driven unprecedented gains in human development in less than a lifetime are also fueling an extraordinary ballooning of humanity’s ecological footprint. The combination of rapid human population growth with even steeper increases in per capita consumption are driving nearly exponential growth in human production and consumption of everything from motor vehicles to synthetic fertilizers, paper, and plastic to water and energy use (Figure 1.2).

Figure 1.2 Metrics of consumption over time show very rapid intensification of global consumption from 1950 to the present across multiple categories including freshwater use, proliferation of motor vehicles, production and use of synthetic fertilizers, production of paper and plastics, and primary energy consumption. Source: Myers SS. Planetary health: protecting human health on a rapidly changing planet. Lancet. 2017;390(10114):2860-2868. Data originally collected by Steffen W, Broadgate W, Deutsch L, Gaffney O, Ludwig C. The trajectory of the Anthropocene: the great acceleration. Anthropocene Rev. 2015;2:81–98; except global plastic production from Geyer R, Jambeck JR, Law KL. Production, use, and fate of all plastics ever made. Sci Adv. 2017; 3: e1700782.

6  Planetary Health: Protecting Nature to Protect Ourselves

As a consequence of this explosion in human consumption, measures of our impacts across the planet’s natural systems—loss of biodiversity, exploitation of fisheries, rising carbon dioxide in the atmosphere, acidification of oceans, or loss of tropical forests— show similarly steep accelerations since the 1950s and 1960s (Figure 1.3). The impacts of people on our planet’s natural systems are now immense. To feed ourselves, we have turned 40% of Earth’s land surface into croplands and pasture.6 We use about half the accessible fresh water on the planet, mostly to irrigate our crops,7 and we exploit 90% of monitored fisheries at or beyond maximum sustainable limits.8 We have cut down roughly half the world’s temperate and tropical forests6 and dammed more than 60% of the world’s rivers.9 And we are crowding out the rest of life on our planet. In May 2019, 145 authors from fifty countries released the Global Assessment of the Intergovernmental Panel on Biodiversity and Ecosystem Services. After reviewing 15,000 articles over 3 years, they concluded that roughly one million species are facing extinction, many within decades.10 Already, we have reduced the numbers of birds, mammals, reptiles, amphibians, and fishes who share the planet with us by more than 50% since 1970.11

Figure 1.3 Metrics of human impact on Earth’s natural systems show rapid intensification since 1950 including loss of biodiversity, exploitation of global fisheries, addition of carbon dioxide to the atmosphere, ocean acidification, and tropical deforestation. Source: Myers SS. Planetary health: protecting human health on a rapidly changing planet. Lancet. 2017;390(10114):2860-2868. Data originally collected by Steffen W, Broadgate W, Deutsch L, Gaffney O, Ludwig C. The trajectory of the Anthropocene: the great acceleration. Anthropocene Rev. 2015;2:81–98

An Introduction to Planetary Health  7

These are, indeed, the best of times and the worst of times. But at the heart of the field of planetary health is recognition that the wellbeing of humanity and the degradation of the rest of the biosphere cannot remain disconnected for much longer. The scale of the human enterprise now surpasses our planet’s capacity to absorb our wastes or provide the resources we are using. Human activities are driving fundamental biophysical change at rates that are much steeper than have existed in the history of our species (see Figure 1.3). These biophysical changes are taking place across at least six dimensions: disruption of the global climate system; widespread pollution of air, water, and soils; rapid biodiversity loss; reconfiguration of biogeochemical cycles, including for carbon, nitrogen, and phosphorus; pervasive changes in land use and land cover; and depletion of resources including of fresh water and arable land. Each of these dimensions interacts with the others in complex ways, altering core conditions for human health: the quality of the air we breathe, the water we drink, and the food we can produce. Rapidly changing environmental conditions also alter our exposures to infectious diseases and natural hazards such as heat waves, droughts, floods, fires, and tropical storms. These changes in the conditions of our lives ultimately affect every dimension of our health and wellbeing, as illustrated in Figure 1.4. Planetary health focuses on understanding and quantifying the human health impacts of these global environmental disruptions and on developing solutions that will allow humanity and the natural systems we depend on to thrive now and in the future.

Figure 1.4 Schematic illustrating impacts of anthropogenic change on human health. Driven by rapid population growth, even steeper growth in per capita consumption, and technologies with large environmental impacts, the scale of human activity now outstrips our planet’s capacity to absorb our wastes or provide the resources we are using. As a result, we are transforming and disrupting most of our planet’s natural systems. Those disruptions interact with each other in complex ways to alter the fundamental conditions for human health and wellbeing and, ultimately, affect nearly every dimension of human health. Source: Myers SS. Planetary health: protecting human health on a rapidly changing planet. Lancet. 2017;390(10114):2860-2868.

8  Planetary Health: Protecting Nature to Protect Ourselves

Organization The first part of this book follows the flow of Figure 1.4. After Chapter 2 presents a brief discussion of where planetary health comes from, its intellectual history, Chapter 3 addresses the critical roles of human population growth and rising per capita consumption as drivers of environmental change. Chapter 4 then explores how these drivers are transforming our planet’s environmental conditions across the dimensions outlined above. The next several chapters explore the many pathways through which those environmental disruptions jeopardize human health: nutrition, infectious disease exposure, noncommunicable disease, population displacement and conflict, and mental health. Next are chapters exploring two special topics: the health impacts of climate change, an emblematic challenge of the Anthropocene, and the phenomenon of happiness—a reminder that there is more to human wellbeing than biomedical health and that the broader view is highly relevant to planetary health. After laying out the health challenges we face, our book turns to the rich terrain of solutions. Chapters on the energy system, urban form, the chemical industry, economic theory, and the private sector explore what we consider pivotal issues: areas in which human activity has caused significant environmental damage but can also move humanity onto a sustainable trajectory. Chapter 17 explores the intersection of planetary health with ethics, and the final chapter describes an optimistic and aspirational future and outlines the steps we could take to get there. Occasionally, throughout these chapters we refer to Planetary Health Case Studies: An Anthology of Solutions, an open-access electronic book produced by The Planetary Health Alliance that can be found at https://islandpress.org/books /planetary-health. This anthology includes ten in-depth planetary health case studies from around the world illustrating diverse environmental drivers, health impacts, and intervention approaches. They all follow a similar arc from describing changing environmental conditions, to exploring the health impacts for a population, to planetary health interventions. Together, they complement much of the material explored in this book.

Overarching Themes The field of planetary health is characterized by several overarching themes that recur throughout this book. These relate closely to the three great challenges identified by the Rockefeller Foundation–Lancet Commission on Planetary Health: conceptual and empathy failures (imagination challenges), knowledge failures (research and information challenges), and implementation failures (governance challenges)12—or, in simple terms, how we think, what we know, and what we do.

The Human Relationship with Nature For too long humans have treated the natural world as a resource to be exploited—as a source of goods and services and as a dumping ground for our wastes. With a small human population and generally low-intensity technology, the global impacts were for

An Introduction to Planetary Health  9

the most part benign. But the Industrial Revolution brought increasingly large-scale alterations to the planet—regions deforested, rivers altered, species extirpated. Dissenting voices ranged from the heartfelt poetry of the Romantics, to the paintings of the Hudson River School, to the ecological advocacy of John Muir and Henry David Thoreau. In contemporary times, several approaches have emerged. One is to quantify the benefits nature provides to people, known as ecosystem services, and to apply this valuation to economic and policy decisions.13-15 Another is to venerate nature for its own sake, quite apart from any human benefit, as does “deep ecology.”16 Still another is to emphasize the human relationship with nature and to value that relationship.17 Planetary health is centered on human wellbeing, so it is especially aligned with the first and third of these approaches, called “instrumental” and “relational,” respectively, but it certainly has room for the second approach (“intrinsic”).

Systems Thinking As noted in Chapter 2, the field of planetary health owes large intellectual debts to ecology. One manifestation of that debt is its reliance on systems thinking. Whether considering the entire value chain of a product (see Chapter 16) or the way changes in wetland ecosystems, triggered by agricultural practices hundreds of miles upstream, alter malaria exposure (see Chapter 6), planetary health emphasizes the way actions ripple through complex systems leading to impacts that can be displaced in time and space. Changes in environmental conditions reflect the sum of myriad actions by countless actors, and those changes, in turn, may have complex consequences on different dimensions of health for different populations. For this reason, thinking across systems and embracing complexity are at the core of planetary health. This type of systems thinking explains, in part, the deeply interdisciplinary nature of planetary health. It is not unusual for health scientists to partner with fisheries ecologists, climate scientists, plant physiologists, economists, atmospheric transport chemists, urban planners, or a variety of other disciplinary specialists in addressing planetary health questions.

Surprises and Unintended Consequences A feature of complex systems is that they yield surprises and unintended consequences. Sometimes the health effects associated with disrupting natural systems are direct and intuitive. More extreme storms combined with sea level rise and degraded coastal barrier systems leave coastal populations more vulnerable to floods and trauma. Loss of pollinating insects reduces pollinator-dependent crop yields (see Chapter 7). But planetary health science is also revealing many surprises. Twenty years ago, we would not have anticipated that anthropogenic CO2 emissions would reduce the nutritional value of our food crops (see Chapter 5). We wouldn’t have guessed that sea level rise and water resource management decisions in Bangladesh would increase groundwater salinity and drive increasing

10  Planetary Health: Protecting Nature to Protect Ourselves

risk of gestational hypertension and preeclampsia in mothers. And an upland farmer in Belize would be surprised to learn that his fertilizer applications were placing his compatriot in the lowlands at higher risk of malaria because of complex changes in wetland ecology. We can expect many more such surprises as we continue our vast global experiment, rapidly altering most of the biophysical conditions to which we and all other life on Earth have adapted over millions of years.

Reducing Vulnerability Is Critical Human disruption of natural systems affects some people more than others. In part, this is because environmental conditions change differently in different places. But it is also because vulnerability to a particular set of biophysical changes in the environment is determined by characteristics of the population itself (Figure 1.4). Good governance, wealth, robust technology and infrastructure, high levels of social capital, access to outside assistance, and aspects of culture and behavior can protect populations from the worst impacts of disrupted natural systems. Communities that can build a sea wall in response to rising sea levels or air condition their homes during a heat wave, fare better than those that cannot. Food trade protects local communities from local crop failures but only when they have the resources to access food markets. Although the root causes may be environmental transformation, in the short term it is often these mediating factors that can be most effectively addressed to reduce the vulnerability of particular populations confronted by rising health risks. As highland communities in sub-Saharan Africa experience increasing risk of malaria with climate change, for example, providing them with access to bed nets is more feasible, at the community level, than slowing climate change (Figure 1.5). Throughout this book it will be valuable to distinguish between mitigation efforts that reduce environmental changes themselves and adaptation efforts that reduce vulnerability to environmental changes already under way—“avoiding the unmanageable” versus “managing the unavoidable.” Both are critical.

There Are Winners and Losers Human activities that disrupt natural systems would generally not take place unless they benefited someone. We dam rivers to generate power or provide water for irrigation. We burn fossil fuels to generate energy. We cut forests and appropriate fresh water to grow crops. We mine minerals to manufacture the conveniences of modern life. But there is often a stark contrast between those who benefit from these activities and those who pay the price in degraded health. Whereas a city or town may realize the benefits of clean energy from a new dam, nearby villagers may experience only a rapid rise in their exposure to schistosomiasis (Figure 1.6). Whereas an entire region may benefit from the energy produced by a new coal-fired power plant, the downwind population will

An Introduction to Planetary Health  11

Figure 1.5 Children inside a bed net in Madagascar. As climate change increases malaria exposure in certain regions of Africa, particularly at higher altitudes, families can do little to mitigate climate change but can adapt, by using bed nets, for example. Source: USAID (Flickr)

experience a rise in air pollution, and future generations bear the brunt of a disrupted global climate. In this context, health impact assessments that make tradeoffs explicit, evaluate the distribution of costs and benefits for different groups over time, and explicitly address equity become essential.

New Ethical Terrain As we discuss in more detail in Chapter 17, the science of planetary health places us in new ethical terrain. It teaches us that each person on the planet, those alive today and those coming in future generations, is connected to every other. Every decision we make about what we eat, how we move around, where we go on vacation, what we purchase, whether or not we own a pet, or even whether we have a child, affects our planet’s natural systems and, as a result, the health and wellbeing of our fellow humans. The impact of each individual decision is infinitesimally small, but collectively they are enormous.

12  Planetary Health: Protecting Nature to Protect Ourselves

Figure 1.6 Senegalese girl doing her washing. Whereas downriver inhabitants may benefit from electricity or access to water for irrigation from a dam, upstream villagers experience greater risk of schistosomiasis. This girl’s open-toed shoes and contact with shallow standing water put her at risk. Source: Courtesy of Hilary Duff

Planetary health science also highlights the closely related issue of equity. In most instances, the poorest people in the world with the fewest institutional, cultural, government, or philanthropic resources to help them are the most vulnerable to rapidly changing environmental conditions. The poor will suffer most from food shortages induced by climate change, and they will contribute the least to rising concentrations of greenhouse gases. Future generations will suffer the consequences of today’s unsustainable consumption patterns. This disconnect between those who reap the benefits and those who suffer

An Introduction to Planetary Health  13

the consequences is deeply unfair. In this light, redoubling our efforts to get humanity on a new trajectory in our management of natural systems becomes not just an urgent health priority but a moral imperative.

Quantifying Externalities One important result of planetary health research is that it quantifies health costs that have previously been only vague externalities. Most of human transformation of natural systems is the result of economic activity at a variety of scales, but in assessing the costs and benefits of these activities, the health effects of environmental transformation have mostly been left out. Whether we are determining the social cost of carbon emissions, the impact of palm oil production in Indonesia, or the costs and benefits of a dam in West Africa, understanding and quantifying the health implications of these activities often changes the equation of costs and benefits considerably. Industries that are using fire to clear land (palm oil, timber, logging, agriculture) lost some of their luster when it became clear that those fires caused roughly 100,000 excess deaths in Southeast Asia in 2015.18

The Role of Political Power In many instances, the problems we face are not so much from a lack of knowledge as the result of special interests knowingly damaging environmental systems for their own benefit while leaving impoverished systems for everyone else. Fossil fuel companies know that their practices are driving climatic disruption but have been reluctant to sacrifice short-term profit for the long-term benefit of humanity. Agricultural and timber industries in Indonesia are aware that the fires they set to clear land are polluting the air and harming the health of downwind inhabitants, but they continue their practices to maximize their profits. These are power problems as opposed to knowledge problems and require different solutions. In some instances, the solutions can come from governments: laws, new policies, subsidies, taxes, and so on. But often they require organizing collective social action or movement building in order to create strong, vocal constituencies that put pressure on both governments and industries to change practices.

Stewardship There are dimensions to planetary health that go beyond the scientific and technical. In addition to the very significant ethical considerations mentioned above, there may also be spiritual dimensions. Is it possible that beneath the ecological crisis we are experiencing, and the public health crisis that it threatens, there is also a spiritual crisis? How did it become acceptable to treat our world’s oceans and its atmosphere as gigantic garbage dumps? When did we stop thinking about the other species with whom we share this planet as our cousins, deserving our compassion and respect? When did the reverence

14  Planetary Health: Protecting Nature to Protect Ourselves

and awe that many of us feel in beautiful natural settings lose their authority to guide our collective decisions? These are questions that speak to our place in the world, our relationship to Nature, and who we are as human beings. As scientists we don’t often ask such questions, but we need to acknowledge them. And perhaps we need to enlist our colleagues in the arts and humanities and members of faith traditions and indigenous communities to help us address them. If our relationship to the natural world is broken, as it seems to be, then science alone will not be enough to fix it.

Hope The degradation of earth systems is gut-wrenching. In practical terms, it threatens the foundations of human thriving. In spiritual terms, it threatens the loss of much that is cherished and even sacred. It is easy to feel hopeless in the face of such losses. But planetary health is dedicated to solutions. Indeed, as this book makes clear, there is much reason for optimism: energy and transportation technologies that are advancing faster than anybody thought possible, innovative agricultural techniques that conserve land and water and reduce the need for chemical inputs, shifts toward more sustainable diets in many wealthy countries, a global youth movement that has riveted the world’s attention, and businesses that are redefining their purpose and taking genuine steps toward sustainability. It is easy to imagine a better future for the world—a future built on health and wellbeing for all, living within planetary boundaries—and many of the pathways to that world are well described.19,20 Hope is realistic, hope is motivating, and as environmentalist David Orr has written, there is no other way: Hope is an imperative.21

Urgency Another note that plays through the following chapters is urgency. We find ourselves at an extraordinary moment in human history with a great drama unfolding. In pursuit of laudable objectives—better, healthier, more comfortable lives—we have expanded the scale of human impacts to the point where our planet’s natural systems are beginning to unravel. Only recently have the stakes come into sharp focus: Continue the current trajectory and doom future generations to a diminished and uncertain future or come together in a vigorous collective renaissance and remake the contours of human society—our systems of food production, urban design, energy production, chemical industry, modes of doing business, and even governance—in order to bring humanity onto a different trajectory. On April 4, 1967, in his speech “Beyond Vietnam: A Time to Break the Silence,” Martin Luther King Jr. observed, “We are now faced with the fact, my friends, that tomorrow is today. We are confronted with the fierce urgency of now. In this unfolding conundrum of life and history, there is such a thing as being too late.”22 Today’s fierce urgency of now

An Introduction to Planetary Health  15

is a biosphere crumbling under our neglect and a growing awareness that our life support systems are starting to fail along with it. Let us join hands, find each other in community, and lead the way in vigorous and positive action.

Authors Samuel Myers, MD, MPH, is a principal research scientist at the Harvard T.H. Chan School of Public Health and director of the Planetary Health Alliance. Howard Frumkin, MD, DrPH is professor emeritus of environmental and occupational health sciences, and former dean, at the University of Washington School of Public Health.

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Roser M, Ortiz-Ospina E. Literacy. Our World in Data. https://ourworldindata.org /literacy. Published September 20, 2018. Accessed September 2019.

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Roser M, Ortiz-Ospina E. Global extreme poverty. Our World in Data. https://ourworld indata.org/extreme-poverty. Published March 27, 2017. Accessed September 2019.

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Roser M. Life expectancy. Our World in Data. https://ourworldindata.org/life-expectancy. Accessed September 2019.

4.

Roser M, Ritchie H. Child & infant mortality. Our World in Data. https://ourworldindata .org/child-mortality. Accessed September 2019.

5.

Jambeck JR, Geyer R, Wilcox C, et al. Plastic waste inputs from land into the ocean. Science. 2015;347(6223):768-771.

6.

Foley JA, Defries R, Asner GP, et al. Global consequences of land use. Science. 2005;309(5734):570-574.

7.

Postel SL, Daily GC, Ehrlich PR. Human appropriation of renewable fresh water. Science. 1996;271(5250):785-788.

8. FAO. The State of World Fisheries and Aquaculture—Opportunities and Challenges. Rome, Italy: Food and Agriculture Organization; 2014. Available at: http://www.fao.org/3/a -i3720e.pdf. 9.

Dams and Development: A New Framework for Decision-Making. London, England: World Commission on Dams; November 2000. Available at: http://staging.unep.org/dams /WCD/report.asp.

10. IPBES. Summary for Policymakers of the Global Assessment Report on Biodiversity and Ecosystem Services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Bonn, Germany: IPBES Secretariat; 2019. 11. WWF. WWF. Living Planet Report 2014: Species and Spaces, People and Places. Gland, Switzerland: World Wide Fund for Nature; 2014. 12.

Whitmee S, Haines A, Beyrer C, et al. Safeguarding human health in the Anthropocene epoch: report of the Rockefeller Foundation–Lancet Commission on planetary health. Lancet. 2015;386(10007):1973-2028.

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13.

Costanza R, d’Arge R, de Groot R, et al. The value of the world’s ecosystem services and natural capital. Nature. 1997;387(6630):253-260.

14. Daily GC, Soderqvist T, Aniyar S, et al. The value of nature and the nature of value. Science. 2000;289(5478):395. 15. Bayles BR, Brauman KA, Adkins JN, et al. Ecosystem services connect environmental change to human health outcomes. EcoHealth. 2016;13(3):443-449. 16. Devall B, Sessions G. Deep Ecology: Living as if Nature Mattered. Layton, Utah: Gibbs Smith; 2001. 17. Klain SC, Olmsted P, Chan KMA, Satterfield T. Relational values resonate broadly and differently than intrinsic or instrumental values, or the New Ecological Paradigm. PLOS One. 2017;12(8):e0183962-e0183962. 18. Koplitz S, Mickley L, Marlier M, et al. Public health impacts of the severe haze in Equatorial Asia in September–October 2015: demonstration of a new framework for informing fire management strategies to reduce downwind smoke exposure. Environ Res Lett. 2016;11(9):1-10. 19. Tallis HM, Hawthorne PL, Polasky S, et al. An attainable global vision for conservation and human well-being. Front Ecol Environ. 2018;16(10):563-570. 20. Bennett EM, Solan M, Biggs R, et al. Bright spots: seeds of a good Anthropocene. Front Ecol Environ. 2016;14(8):441-448. 21. Orr DW. Hope Is an Imperative. Washington, DC: Island Press; 2011. 22. Martin Luther King Jr. “Beyond Vietnam: A Time to Break the Silence.” Delivered on April 4, 1967. https://www.americanrhetoric.com/speeches/mlkatimetobreaksilence .htm.

2 Assembling Planetary Health: Histories of the Future James Dunk and Warwick Anderson

The long-term bottom line of global environmental degradation, wrote Australian epidemiologist Anthony J. McMichael (Figure 2.1) nearly three decades ago, would be its adverse effects on human health.1 Awareness of this predicament was growing rapidly. In the previous year, the Intergovernmental Panel on Climate Change released its severe assessment of the consequences of climate change,2 and the World Health Organization3 and Australian National Health and Medical Research Council4 issued reports on the health consequences of greenhouse gases. These were stimulated by the findings of the World Commission on Environment and Development in 1987.5 The afflictions captured in these communiqués—global warming, ozone depletion, land degradation, acid rain, biodiversity loss, and deterioration in the quality of air, soil and water—were occurring on an unprecedented scale. The technological proficiency and zeal for consumption of rapidly expanding human populations were disturbing the life support systems of the planet. Although every species was threatened, it was the threat to human life that might produce real action. The international health sector had new mandates: to expand public health to the scale of the planet; to incorporate new environmental knowledge into its repertoire, collaborating more closely with ecologists and climate scientists; and, perhaps most importantly, to be prepared to develop broad and bold policy recommendations based on modelling and predictions. This time the public health community would not be able comfortably to sit back and analyze evidence. Those who wanted to protect human health, argued McMichael, would now need to “anticipate the future.”1

17

18  Planetary Health: Protecting Nature to Protect Ourselves

Figure 2.1 Anthony (Tony) McMichael. McMichael was a pioneer in alerting the public health community to the human health implications of accelerating global environmental change. Source: Photo by Belinda Pratten

The history of what came to be known commonly, around 2010, as “planetary health” is both short and extremely long. Short in the sense that epidemiologists such as McMichael and organizations such as the World Health Organization did not recognize the risks of climate change and destruction of the planet’s life support systems to human population health until the 1980s. Shorter still in that the specific term was commonly applied to the health of the planet from the 1990s and then to the effects of planetary spoliation on humans only in the second decade of the twenty-first century. But very long in the sense that the environment in various forms and at different scales has figured in the calculus of human health and disease for thousands of years. Long, too, is the history of medical activism and advocacy extending beyond the clinic and into the realms of politics and policymaking. In this chapter we focus on the recent history, since World War II, of what we now call planetary health, the latest instantiation of environmental health, as amalgamated with systems ecology, planetary thinking, and health activism.6 We argue that these particular origins and influences make planetary health a distinct formation of global health, a divergent configuration in which environmental ethics on a planetary scale productively meets human population health.

Assembling Planetary Health: Histories of the Future  19

The environment has figured in the practice of Western medicine from its Hippocratic foundations. The revered fifth-century text Airs, Waters, Places advised physicians to attend to all aspects of the environment—seasons, winds, soils, and waters. The human body was viscerally in touch with its surroundings, exquisitely sensitive to dampness, heat, chills, drafts, and seasonal changes, shifting accordingly along a continuum between health and sickness. Longitude and altitude, proximity to the coast, and forest cover shaped disease expression. Place and climate mattered to patients and their physicians.7 This medical geography became increasingly important as Europeans set sail and traveled, for as human bodies moved into new environments, they risked new diseases (Figure 2.2). New and potentially noxious environments thus required clearing and cultivation; medicine became a discourse on how to colonize and settle.8,9 By the end of the nineteenth century, however, with the rise of germ theory and increasing confidence in technologies that might insulate vulnerable bodies from their surroundings, environmental sensibilities declined in medicine, although they were never banished entirely. A century

Figure 2.2 Painting by John Vanderlyn depicting Christopher Columbus and members of his crew arriving on a beach in the West Indies on October 12, 1492. Medical geography became increasingly important as Europeans moved across oceans and became exposed to new illnesses while bringing their own diseases to previously unexposed populations. Source: Wikimedia Commons

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later, the detrimental effects of enormous projects of colonization, industrialization, and economic growth and development began to be identified in the air, the seas, and the very earth underfoot. Environmental alterations or “improvements” once undertaken to make particular localities healthier had been massively amplified and were now among the factors making the planet potentially uninhabitable. Older medical geographies had been fragmentary and patchy, scaled down, calling for the “improvement” of country or for movement from an unhealthy place to a more salubrious locale. Now the stability of natural systems as a whole, on a global scale, threatened to spiral out of control, and healthy sites were ever scarcer. The scale of contemporary ecological challenges calls for more than piecemeal medical geography or climatology and more than an older environmental health that focused on isolated toxicity and other hazards—formulations adequate perhaps to address concerns such as those raised by Rachel Carson in Silent Spring (1962) but insufficient to register globally. But what are the resources for this more encompassing conceptualization? Starting in the late 1940s and accelerating during the Cold War, demographers and environmentalists warned of the dangers of human population growth, urbanization, and overconsumption, all threatening to become unsustainable and overload the planet’s carrying capacity. At the same time, the massive proliferation of nuclear weapons portended the destruction of life and civilization on Earth. Such grim forebodings directed attention to planetary scale in the postwar era. Meanwhile, some ecologists were incorporating systems thinking into models of the interactions of life forms and their environments, observing energy flows, circular causal systems, feedback loops, and thresholds or tipping points. In Planetary Overload (1993), McMichael brought the planetary frame, systems ecology, and epidemiology into conversation.10 Thus, he was able to call on those entrusted with preserving human life to reconceive health within an ecological framework capable of understanding planetary disruptions—and to address their health effects without doing further violence to overburdened systems.11 This became the central dogma of transdisciplinary planetary health when it emerged some 20 years later with the encouragement of the Lancet and the Rockefeller Foundation. It is predicated on the notion that human health and civilization depend on the health of the planet’s natural systems, and comprehending these systems requires bringing together environmental and epidemiological evidence in complex models.12 Planetary health therefore has emerged as an innovative configuration of medical thinking, a new, more complex, and realistic understanding of health and disease as they become manifest on an ailing planet. Some years ago, historian Charles E. Rosenberg distinguished “configuration” in medicine and public health, the emphasis on structure and relationship, from “contamination,” the resort to microbe hunting or the simple tracking of pathogens.13 Mounting evidence of disruption to planetary life support systems has compelled

Assembling Planetary Health: Histories of the Future  21

public health experts and epidemiologists to develop new explanatory frameworks and configurations, drawing together many older environmental apprehensions and cognitive resources, in order to fashion planetary health.

Planetary Thinking, Systems Ecology, Environmental Health If we want to understand the appearance of planetary health, we need first to consider how environmental thinking went planetary after World War II. The war was understood as being, at least in part, a war over natural assets. In its aftermath, as economists and diplomats encouraged massive investment in reconstruction programs, anxiety grew about the limits to these resources on an ever more connected and bounded planet.14 “The earth is constantly becoming smaller” wrote New York conservationist Henry Fairfield Osborn, Jr., in Our Plundered Planet (1948), “or rather our knowledge of it is leading us to think of it as diminishing rapidly.”15 The same year, American ornithologist William Vogt warned of imminent overload of the planet’s “carrying capacity” in relation to the human species, applying a term that chiefly had been used for animals on settler colonial rangelands. In failing to see the planet ecologically, as an interconnected whole, world leaders were facilitating the rapid destruction of the physical environment and the species that depended on it, falling deeper and deeper into “an ecological trap.” Vogt wrote in the shadow of the “dramatic and fearful pageants” of Nagasaki and Hiroshima, now toxic wastelands that focused attention on environmental vulnerability. “Disregarded they will almost certainly smash our civilization.”16 These warnings provoked some public interest, but they did not really blast off until the rise of environmentalism in the 1960s. Reflecting on the postwar period of increasing prosperity—later heralded as “the great acceleration” for the steep growth in production, consumption, and population—Paul R. Ehrlich’s The Population Bomb (1968) prophesied massive starvation and misery.17 Economists Barbara Ward18 and Kenneth Boulding19 borrowed vocabulary from the space race to suggest that our planet was as fragile as it seemed from afar (Figure 2.3). Although the earth’s economy differed in scale from those of the vessels being launched into the sky it, too, was closed, interdependent, and finite. There were limited resources to plunder and little capacity to absorb the waste products of such plundering. Just as careful planning was necessary to ensure that astronauts had enough to eat and drink and supplies of energy, it would be necessary to strategize to support the life of populations on “Spaceship Earth.” For some, “sustainability” became the rage. Ecologist Barry Commoner suggested that it was not overpopulation but the technological configuration of developed societies, their excessive patterns of consumption, that would lead to catastrophe. He articulated a series of fundamental ecological laws in The Closing Circle (1971), which aligned with the arguments of the radical economists.

22  Planetary Health: Protecting Nature to Protect Ourselves

Figure 2.3 Earth as seen from the surface of the moon. Photos like these taken from the Apollo missions in the 1970s helped stimulate a new awareness of the unique beauty and fragility of a planet under human pressure. Source: Public domain

Everything was connected to everything else, and everything had to go somewhere. There was no “waste” because there was nowhere to put the useless byproducts of human activities. Nature, emphasized Commoner, was characterized by interaction and connectivity.20 Leaders in other fields also became disturbed by the reckless international commitment to economic growth and the failure to heed ecological cautions. Sometimes they could be found in unexpected places. Alexander King, for example, was in charge of scientific affairs at the Organisation for Economic Co-operation and Development (OECD) when he and Italian industrialist Aurelio Peccei gathered together scientists, economists,

Assembling Planetary Health: Histories of the Future  23

and industrialists in 1968 to form the Club of Rome. Indeed, most of the group’s early leaders came from the science department of the OECD, thereby creating an intellectual insurgency against the postwar economic order entrenched by the host organization.21 Addressing themselves to the growing complexity and interrelation of a range of global problems, each with environmental implications, they blazed a path in forecasting the future and demonstrated the way that networks of transnational elites and experts might intervene on a planetary scale. They turned to nascent computer science and its supposedly objective algorithms to analyze the interlocking problems besetting the world. Released in 1972, their report, Limits to Growth, proved immensely influential and deeply unsettling.22 Limits to Growth signaled an amplification of concern about the condition of the planet. Additionally, in 1972 a landmark meeting, the United Nations Conference on the Human Environment, took place in Stockholm, Sweden. In preparation for the conference, economist Barbara Ward and microbiologist, environmentalist, and member of the Club of Rome René Dubos (Figure 2.4) were commissioned to detail scientific evidence of environmental peril from a multitude of countries and disciplines. Their book, Only One Earth: The Care and Maintenance of a Small Planet (1972), copiously catalogued the harm that global industrial capitalism was doing to the planet’s life support systems. The earth was growing ever smaller, more connected, and more exploited and depleted.

Figure 2.4 René Dubos. In the mid-nineteenth century Dubos was an early voice raising the alarm about the human relationship with the natural world gone awry. Source: Courtesy of Rockefeller Archive Center

24  Planetary Health: Protecting Nature to Protect Ourselves

In the 1960s and 1970s, increasing agitation about deteriorating planetary environments began to worry ecologically inclined medical scientists. Based at Rockefeller University, New York, Dubos placed himself in the forefront of the new medically inflected environmentalism. Since the 1940s, the ecological interactions of microbes and their hosts, their patterns of competition and mutualism, had fascinated him.23 After the war, he began to channel his scientific interests into popular books that addressed medical and ecological themes. Thus, he extolled the peaceful coexistence of humans and microbes in Mirage of Health (1959).24 In 1965, Man Adapting proposed that disease should be understood as the failure of an organism to adjust to its environment. The same logic could be applied on a grand scale: Contemporary humanity, retaining the physiology of its hunter– gatherer ancestors, now found itself in a highly industrialized and overcultivated physical environment radically different biologically from those in which it had evolved.25 In Man, Medicine, and Environment (1968), Dubos observed that just as all natural phenomena manifested complex patterns of relationships, all instances of disease issued from complex relations between body, mind, and environment. Global capitalism, he suggested, was doing grievous damage to each entangled entity, especially to the ecosystems that supported human life.26 Dubos’s critique of postwar life—atomized, automated, mechanized, a dismal contrast to the active lives of paleolithic ancestors—helped animate the protest movements of the 1960s, and he became an unlikely hero of the counterculture that alarmed international business leaders and policymakers. Dubos’s rising environmentalist fervor came also to inspire a younger immunologist colleague, Stephen V. Boyden. While at Rockefeller University, Boyden spent several weekends with Dubos and his wife at their house near Poughkeepsie, upriver from New York City. Walking in the woods, Boyden recalled, they often “talked about the relevance of the evolutionary background of Homo sapiens for understanding human behaviour, as well as human health and disease, in the modern setting.”27 Later at the Australian National University (ANU), in Canberra, Australia’s rustic “bush capital,” Boyden abandoned immunology to develop a program in human ecology and environmental studies, inspired in part by his reading of Rachel Carson’s Silent Spring (Figure 2.5) and conversations with Dubos. He was particularly disturbed by the uncoupling of human culture from human biology, with ruinous implications for the physical environment. “Not only is culture itself a product of biological evolution,” he wrote, “but it depends on biological processes for its continued existence; and ever since the Neolithic development there has occurred a complex and highly significant interaction between the forces of nature and those of culture.”28 In the 1970s, during his investigation of the urban ecology of Hong Kong, Boyden further worked up his impressions of the relations between evolution and human health, describing the “principle of phylogenetic maladjustment,” which bore strong resemblances to Dubos’s diagnosis of misfit and stress; following Dubos, he was

Assembling Planetary Health: Histories of the Future  25

Figure 2.5 Rachel Carson. With her publication of Silent Spring in 1962, Carson deeply influenced thinking about human–environment interactions, helping to stimulate the environmental movement and stimulating the thinking of many figures in this history. Source: U.S. Fish and Wildlife Service

exploring the dire biological and cultural implications of human technological progress. Boyden proposed the concept of “techno-addiction,” a pathological dependence on technology that diverted attention from biological conditions necessary for “optimal health,” those under which the species had evolved as hunter–gatherers. Like Dubos, Boyden came to deplore the “diseases of civilization,” the pathologies of development and progress.29,30 In 1972, he warned medical readers of the “galloping techno-demographic processes which threaten the integrity of the biosphere,” including air and water pollution, contamination with pesticides, and overcrowding in urban communities. “Following the introduction of fossil fuels,” he wrote presciently, the energy flowing through societies had accelerated so dramatically that “the integrity of the biosphere as a whole is now considered by many ecologists to be in jeopardy.”31 Boyden’s work explicitly connects emergent planetary health with a longer tradition of twentieth-century ecological thought, especially with postwar systems ecology.32 British plant ecologist and psychoanalyst Arthur G. Tansley had coined the term “ecosystem” in 1935, and Yale limnologist G. Evelyn Hutchinson elaborated on the mechanisms of “circular causal systems” over the next decade.33 Organisms were “acted upon by their environment, and they may react upon it,” wrote Hutchinson. These relations tended to correct themselves but might be thrown by the violent intrusion of new species or other variables.34 He was drawing on the mathematical models of Alfred J. Lotka, particularly his theories of biodemographic circular causality.35 The Yale biologist was also eager to integrate Ludwig von Bertalanffy’s general system laws36 and Norbert Wiener’s theory of cybernetics37 with the concept of the “biosphere,” as imagined by Russian geochemist Vladimir I. Vernadsky. For Vernadsky, the biosphere was the sum of biological life, always transforming

26  Planetary Health: Protecting Nature to Protect Ourselves

the inanimate geosphere.38,39 Hutchinson thus tried to restructure ecology in relation to systems theory, cybernetics, and ideas about the biosphere, scaling up from lakes to the earth as a whole. One of his students, Raymond L. Lindeman, in 1942 described a lake as “an ecosystem of energy flowing through physical-chemical-biological processes.”40 In the 1950s, Howard T. Odum and his brother Eugene P. Odum, both mentored by Hutchinson, helped to develop the new systems ecology. They outlined the working of large cyclical entities, or energetic systems, and made predictive generalizations that could be scaled up, even to the size of the planet.41 In time these approaches would develop precise techniques for studying—and potentially solving—the massive, large-scale, interlinked problems that became ever more apparent as the twentieth century drew to a close.42 A future pioneer of planetary health, McMichael, as a medical student in Adelaide in the 1960s, had been exposed to broader social and environmental strands of medical thought through his mentor, Basil Hetzel, a forceful advocate of social medicine.43 McMichael became a radical student leader, avidly reading Carson’s distressing descriptions of the physiological and environmental effects of pesticides,44 Ehrlich’s Malthusian condemnation of the human population explosion,17 and Dubos’s and Boyden’s visions of harmonious relations between humans and the other species with which they shared the earth.25 “Postwar affluence is being tempered with the realization that unrestrained modern technology is unleashing new agents of biological damage—radioactive wastes, noxious fumes, persistent pesticides, heavy metal contaminants, and so on,” wrote McMichael in 1972 for his “Spaceship Earth” column in the progressive Australian magazine The Review.45 The epidemiologist thus was prepared, even preadapted, to explain the complex implications for human health of anthropogenic climate change, when it was recognized later in the century.

The Nuclear Option The eerie light of nuclear weapon tests lit up another possible path toward planetary health. From the early 1960s, a group of Boston-based physicians, incensed that the nuclear arms race threatened environmental devastation on a planetary scale, began to advocate for global disarmament and denuclearization. A leading figure in this movement, cardiologist Bernard Lown, surmised in 1961, during a speech by Nobel Peace Prize laureate Philip Noel-Baker, that nuclear war, not cardiac arrest, posed the greatest present threat to human health.46 Lown and colleagues founded Physicians for Social Responsibility (PSR), and together wrote a series of articles in the New England Journal of Medicine. They were encouraged by editor Joseph Garland, who justified attention to the nuclear threat as an expression of physicians’ commitment to the survival of humanity.47 In a vivid example of speculative reportage, one article warned of the consequences of a thermonuclear hit on Boston—both the direct loss of life, the immediate aftermath, and

Assembling Planetary Health: Histories of the Future  27

the longer-range ecological and economic implications. Post-blast human life, it argued, would be extremely precarious.48 At the height of the Cold War, PSR prospered for a time and extended its influence around the world, but with later détente between the United States and Soviet Union, its antinuclear campaign came to appear less urgent and compelling. Some activist physicians turned instead to protesting against the involvement of the United States in the Vietnam War.49 After waning for more than a decade, PSR was reinvigorated in 1978 amid concerns that the major powers continued to stockpile nuclear weapons. They conducted “bombing runs” in medical schools and public halls—vivid descriptions of nuclear strikes over the cities in which they spoke, modeled after their original articles.50 During this period, Lown became attracted to the possibility of U.S.–Soviet medical diplomacy as a means of combating government hostility and obduracy. Late in 1980, he and other American physicians joined a number of Soviet physicians led by Yevgeniy Chazov to create International Physicians for the Prevention of Nuclear War (IPPNW), which was awarded the Nobel Peace Prize in 1985. Meanwhile, the revitalized PSR decided to expand its medical advocacy to encompass broader environmental problems while still modeling its interventions along the lines of the earlier antinuclear campaigns. Among the PSR members most passionately addressing broader environmental hazards to human health was Alexander Leaf, a physician at Massachusetts General Hospital and founder of Harvard’s Department of Preventive Medicine and Clinical Epidemiology.51 As Leaf monitored the mounting evidence of ecological disruption on a global scale, the epidemiological threats became clear to him. In 1989, he shared his concerns with Arnold S. “Bud” Relman, then editor of the New England Journal of Medicine, who urged him to write an article on the subject.52 Leaf noted that despite recent scientific interest in climatic and environmental change, the impact on human health had not been widely discussed. Consequences of air pollution seemed obvious—and experienced daily. Excessive sun exposure due to ozone depletion was leading to increased incidence of skin cancers and eye cataracts, and possible depression of the immune system. The human population “explosion” was putting profound stress on agricultural production and food supplies. And although the health outcomes of global warming promised to be severe, they remained nebulous. It was nevertheless clear, Leaf declared, that the planet’s ecosystems could not sustain such bullish economic growth and development. The biosphere was imperiled as never before, he argued—the “effects of environmental change may be analogous to nuclear war,” an impending disaster long dreaded. “What role do we have as physicians and health professionals,” he asked, “in dealing with these global climatic and environmental changes?”53 A number of Leaf’s colleagues in PSR and at Harvard showed themselves ready to respond to his provocation. In 1993, psychiatrist Eric Chivian founded the Center for Health and the Global Environment at the Harvard Medical School. Chivian, a co-founder

28  Planetary Health: Protecting Nature to Protect Ourselves

of IPPNW, now wrote lucidly about the health dangers to human populations of environmental degradation and the disappearance of other species, and the center’s associate director, Paul R. Epstein, worked to promote a more encompassing vision of environmental health, emphasizing activism and social change.54 The Harvard Center for Psychological Studies in the Nuclear Age, led by psychiatrist John Mack, a member of PSR and IPPNW, changed its name to the Center for Psychology and Social Change in 1992, claiming a broader mandate with strong emphasis on the psychology of environmental crises.55 On the publication of a 20-year update of the influential first Club of Rome report,56 the center organized a seminar with lead author Donella Meadows titled “Beyond the Limits: The Environment’s Challenge to the Human Psyche.”57 Without a concerted research agenda, however, the efforts at Harvard to link public health to the condition of the planet’s natural systems faltered for a time. Not until the early twenty-first century, with the establishment of the Planetary Health Alliance at the Harvard T.H. Chan School of Public Health, would global environmental health concerns gain much traction there.

Assembling Planetary Health At the turn of the century, the conceptual framework, along with the environmental and epidemiological evidence base, was being assembled. Appointed professor of epidemiology at the London School of Hygiene and Tropical Medicine in 1994, McMichael soon encountered other medical scientists speculating on the ramifications of global environmental degradation, including Andrew Haines, who also had been a leading voice in IPPNW. Mobilized by the stream of warnings from environmental scientists, Haines since 1990 had been alerting colleagues of the health implications of global warming. The elevation in global average temperatures and accompanying rising sea levels and reduction in arable land, he predicted, would produce an increase in respiratory problems and accelerate the spread of infectious diseases as vectors extended their geographic range.58 McMichael and Haines worked together, prolific in issuing warnings to the international community. “Anthropogenic climate change signifies that for the first time the aggregate global impact of humankind exceeds the physical and ecological limits of the biosphere,” they wrote in 1997. “This greatly extends the temporo-spatial scale of environmental health beyond our usual concern with localized and immediate exposures to toxic or infectious agents.”59 Having moved from London to Canberra, where he directed the National Centre for Epidemiology and Population Health at the ANU, McMichael continued to campaign vigorously. “We are at a substantive, not merely a millennial, crossroads,” he wrote in 2000. Now, human-induced global ecosystem change “jeopardizes the life-supporting capacity of the biosphere.”60 A few years later, he repeated his admonition that “population

Assembling Planetary Health: Histories of the Future  29

growth and the aggregated pressures of consumption and emissions are beginning to impair various global environmental systems. . . . To assume an immunity of modern human societies to adverse environmental conditions would be imprudent, indeed naïve.”61 McMichael helped lead change within the United Nations system, including workshops assessing the risks of the changing planetary environment for human health run by the World Health Organization, the World Meteorological Organization, and the United Nations Environment Program.62 McMichael’s last book, Climate Change and the Health of Nations, published posthumously in 2017, was a plea for urgent and concerted global efforts to address climate change, environmental degradation, and the loss of biodiversity.63 He had embraced the recent delineation of nine “planetary boundaries”—critical thresholds circumscribing a “safe operating space” for humanity to enjoy reasonable prospects of health and survival.64 McMichael’s life’s work had been dedicated to critical inquiry into the prospects of human health in the face of a mounting ecological catastrophe. According to Boyden, writing a eulogy for the epidemiologist, McMichael had understood earlier than most that the health of ecosystems underpinned the health of the human species, and protecting the former might save the latter.65 As the new century advanced, Richard Horton, editor of The Lancet, committed the journal to addressing pressing global and systemic environmental issues in human health, publishing a series of incisive articles by Haines, McMichael, and others. In 2010, the Rockefeller Foundation joined The Lancet in promoting a “new health discipline—public health 2.0.” The endeavor went “beyond the boundaries of our existing global health frameworks,” wrote foundation president Judith Rodin, “to take into consideration the natural systems upon which human health depends.”66 Along with the Gordon and Betty Moore Foundation, it established Health and Ecosystems: Analysis of Linkages (HEAL), which evolved into the Planetary Health Alliance, and launched a commission together with The Lancet. Chaired by Haines, with a large and influential team of researchers, the commission met at Bellagio, Italy, in July 2014 and in the next year issued its momentous report, Safeguarding Human Health in the Anthropocene Epoch (Figure 2.6).12 Horton’s preferred designation of the new investigatory enterprise, “planetary health,” rapidly gained currency. In 2015, the Wellcome Trust launched a priority area called Our Planet, Our Health, with a £75 million investment, hoping to generate substantive new research and action on the health effects of climate change, deteriorating urban environments, and challenges to global food systems. International journals Lancet Planetary Health and the American Geophysical Union’s GeoHealth were established in 2017, Nature Sustainability began publishing in 2018, and in the same year the interdisciplinary journal Challenges partnered with the inVivo network to promote planetary health. Elusive in the 1990s, a research program and a definite agenda for advocacy in the new planetary health were coming into view.

30  Planetary Health: Protecting Nature to Protect Ourselves

Figure 2.6 The Rockefeller Foundation–Lancet Commission on Planetary Health in Bellagio, Italy. The commission convened in July 2014 and released their report “Safeguarding Human Health in the Anthropocene” the next year. Source: Courtesy of the Rockefeller Foundation Bellagio Center

Conclusion Genealogies of contemporary intellectual formations or amalgams, such as the one we have traced here, can help elucidate continuing founder effects and persisting influences on how we imagine ourselves and the world around us. They convey a sense of the dimensions, the quality, and the relations of our cognitive toolkits. They might even suggest a sort of inevitability about our conjectured destination. In contrast, they also can indicate unconscious resistances and opportunities missed, revealing conceptual deficiencies and limitations, blockages that might otherwise have evaded attention. Even a cursory history of planetary health causes us to question its relations with prevailing “global health.” Global health began to flourish in the 1990s, in part in response to the perceived failures of national and international health services to address emergent infectious diseases.67 With the support of nongovernment organizations and philanthropic foundations, global health programs generally focus on control of specific diseases, often resorting to modular, top-down, or vertical health interventions dependent on technological fixes and simplistic metrics.68 Whether driven by humanitarian or biosecurity concerns, global health has sometimes assumed, according to several critics,

Assembling Planetary Health: Histories of the Future  31

a neocolonial authority.69 It is tempting to regard planetary health as a modest, if necessary, supplement to global health, operating on the same scale but concentrating on ecosystem disruption more than on infectious disease outbreaks. But history suggests otherwise. The origins of planetary health, as we have seen, can be traced rather to a long tradition of environmental health, combined with systems ecology and radical postwar planetary thinking—a genealogy separate from that of global health, despite occasional family resemblances and convenient affiliations. To a degree, planetary health represents our current response to what might be called the dark side of development, progress, and the “civilizing process,” a means of contending with the consequences of our species’ incessant assault on the planet’s life support systems. It is our natural reaction to nature biting back. No surprise, then, that the amalgam of planetary health coalesced most readily, and earliest, in settler societies such as the United States and Australia and in former imperial centers such as London, places that know well the ecological disruption attendant on European exploitation and settlement, the environmental ravages of invasive species, land clearing, rapid urbanization, mining, and unsustainable agriculture.70 Historians have observed that conservationism developed first in the British empire in opposition to exploitation and destruction of delicate natural systems;71 similarly, ecology more broadly has been designated a “science of empire.”72 Planetary health, too, seems to offer an internal critique of colonialism and heedless economic growth, embedded in the “sustainable development” heralded by the World Commission on Environment and Development through to recent critiques of gross domestic product as a viable measure of economic health.73 Finally, the history of planetary health allows us to reflect once more on the contingency of our knowledge of human populations and global ecosystems and their multiple interactions. It is surely significant that, so far, our historical narrative swarms with wellmeaning white male experts from the Global North—like us, it must be noted. Some crucial exceptions do come to mind: Barbara Ward, Donella Meadows, and Gro Brundtland (chair of the paradigm-shifting World Commission on Environment and Development) to name a few. But how, we wonder, might planetary health be transformed as it comes to incorporate the insights of more women, people from the Global South, and Indigenous intellectuals?

Authors Warwick Anderson, MD, PhD is a historian of the biological and biomedical sciences, focusing recently on the development of disease ecology in the twentieth century. He is the Janet Dora Hine Professor of Politics, Governance and Ethics in the School of Philosophical and Historical Inquiry and the Charles Perkins Centre at the University of Sydney. Additionally, he is an honorary professor in the School of Population and Global Health at the University of Melbourne.

32  Planetary Health: Protecting Nature to Protect Ourselves

James Dunk, PhD is a cultural historian working in the history of medicine and mental health and planetary history. His current research focuses on efforts to reinvent psychology and psychiatry in the ecological crisis of the late twentieth century. He lives and works on Gadigal land, in Sydney, and is a research fellow in the Department of History at the University of Sydney and a conjoint fellow in the School of Humanities and Social Sciences at the University of Newcastle.

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10. McMichael AJ. Planetary Overload: Global Environmental Change and the Health of the Human Species. Cambridge, UK: Cambridge University Press; 1993. 11. McMichael AJ. Ecological disruption and human health: the next great challenge to human health. Aust J. Public Health. 1992;16(1):3–5. 12.

Whitmee S, Haines A, Beyrer C, et al. Safeguarding human health in the Anthropocene epoch: report of The Rockefeller Foundation–Lancet Commission on Planetary Health. The Lancet. 2015;386(10007):1973–2028.

13. Rosenberg CE. Explaining epidemics. In: Explaining Epidemics and Other Studies in the History of Medicine. Cambridge, UK: Cambridge University Press; 1992:293–304. 14. Warde P, Robin L, Sörlin S. The Environment: A History of the Idea. Baltimore, MD: Johns Hopkins University Press; 2017. 15. Osborn HF Jr. Our Plundered Planet. New York, NY: Pyramid Publications; 1948:33. 16. Vogt W. Road to Survival. New York, NY: William Sloane; 1948:14–16, xiii. 17. Ehrlich PR. The Population Bomb. New York, NY: Ballantine Books; 1968. 18. Ward B. Spaceship Earth. New York, NY: Columbia University Press; 1966.

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19. Boulding KE. The economics of the coming spaceship earth. In: Jarrett H, ed. Environmental Quality: Issues in a Growing Economy. Baltimore, MD: Johns Hopkins University Press; 1966:3–14. 20. Commoner B. The Closing Circle: Nature, Man, and Technology. New York, NY: Knopf; 1971. 21.

Schmelzer M. “Born in the corridors of the OECD”: the forgotten origins of the Club of Rome, transnational networks, and the 1970s in global history. Journal of Global History 2017;12(01):26–48.

22. Meadows DH, Meadows DL, Randers J, Behrens WW III. The Limits to Growth: A Report for the Club of Rome’s Project on the Predicament of Mankind. New York, NY: Universe; 1972. 23. Dubos RJ. The Bacterial Cell in Relation to Problems of Virulence, Immunity and Chemotherapy. Cambridge, MA: Harvard University Press; 1945. 24.

Dubos RJ. Mirage of Health: Utopias, Progress, and Biological Change. London, UK: George Allen & Unwin; 1959.

25. Dubos RJ. Man Adapting. New Haven, CT: Yale University Press; 1966. 26. Dubos RJ. Man, Medicine, and Environment. New York, NY: Praeger; 1968. 27. Boyden S, personal communication with James Dunk, December 2, 2018. 28. Boyden S. The impact of civilisation on human biology. Aust J Exp Biol Med Sci. 1969;7:287–298. 29. Boyden S. Evolution and health. The Ecologist. 1973;3:304–309. 30. Rosenberg CE. Pathologies of progress: the idea of civilization as risk. Bull Hist Med. 1998;72:714–730. 31. Boyden S. The environment and human health. Med J Aust. 1972;i:1229–1234. 32. Anderson W. Natural histories of infectious disease: ecological vision in twentiethcentury biomedical science. Osiris. 2004;19:39–61. 33. Tansley AG. The use and abuse of vegetational concepts and terms. Ecology. 1935;16:284–307. 34.

Hutchinson GE. Circular causal systems in ecology. Ann N Y Acad Sci. 1948;50:221–246.

35. Lotka AJ. The Elements of Physical Biology. Baltimore, MD: Williams and Wilkins; 1925. 36. Bertalanffy L. An outline of general systems theory. Br J Philos Sci. 1950;1:139–164. 37. Wiener N. Cybernetics, or Control and Communication in the Animal and the Machine. Cambridge, MA: MIT Press; 1948. 38. Vernadsky VI. La Biosphere. Paris, France: Félix Alcan; 1929. 39. Vernadsky VI. Problems of biogeochemistry. II: the fundamental matter–energy difference between the living and inert natural bodies of the biosphere. Trans Conn Acad Arts Sci. 1944;35:485–517. 40. Lindeman RL. The trophic–dynamic aspect of ecology. Ecology. 1942;23:399–418. 41. Odum HT, Odum EP. Fundamentals of Ecology. Philadelphia, PA: W.S. Saunders; 1953. 42. Dyball R, Newall B. Understanding Human Ecology: A Systems Approach to Sustainability. Abingdon, UK: Routledge; 2014. 43. Hetzel B. Chance and Commitment: Memoirs of a Medical Scientist. Adelaide, Australia: Wakefield Press; 2006. 44. Carson R. Silent Spring. New York, NY: Houghton Mifflin; 1962.

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45. McMichael T. Spaceship Earth. The Review 1972(April 8–14):708. 46. Lown B. Medical internationalism and the “last epidemic.” In: Brown TM, Birn A, eds. Comrades in Health: U.S. Health Internationalists, Abroad and at Home. New Brunswick, NJ: Rutgers University Press; 2013. 47. Garland J. The medical consequences of thermonuclear war—editor’s note. N Engl J Med. 1962;266(22):1126. 48. Ervin FE, Glazer JB, Aronow S, et al. Thermonuclear attack on the United States. N Engl J Med. 1962;266(22):1127–1137. 49. Alexander S. The origins of Physicians for Social Responsibility (PSR) and International Physicians for the Prevention of Nuclear War (IPPNW). Soc Med. 2013;7(3):120–126. 50. Lifton RJ. Witness to an Extreme Century: A Memoir. New York, NY: Free Press; 2011:151. 51. Leaf A. Medicine or physiology: my personal mix. Ann Rev Physiol. 2001;63(1):11–14. 52. Alexander Leaf, M.D.: Autobiographical Memoir and Oral History Interview with Arnold S. Relman, Countway Library, R154.L53. 1996:545. 53. Leaf A. Potential health effects of global climatic and environmental changes. N Engl J Med. 1989;321:1577–1583. 54.

Chivian ES, McCarthy M, Hu H, Haines A, eds. Critical Condition: Human Health and the Environment. Cambridge, MA: MIT Press; 1993.

55. Smith DM. The Center’s transition: near and far. Centre Review. 1992;6(2):2. 56.

Meadows DH, Meadows DL, Randers J. Beyond the Limits: Global Collapse or a Sustainable Future. London, UK: Earthscan Publications Ltd; 1992.

57. Center for Psychological Studies in the Nuclear Age. Beyond the Limits: The Environment’s Challenge to the Human Psyche, April 7, 1992. John E. Mack Archives. 58. Haines A. The implications for health. In: Leggett J, ed. Global Warming. Oxford, UK: Oxford University Press; 1990:149–162. 59. McMichael AJ, Haines A. Global climate change: the potential effects on health. BMJ. 1997;315:805–809. 60. McMichael AJ, Beaglehole R. The changing global context of public health. The Lancet. 2000;356:495–499. 61.

McMichael AJ. Population, environment, disease, and survival: past patterns, uncertain futures. The Lancet. 2002;359:1145–1148.

62. McMichael AJ, Campbell-Lendrum DH, Corvalán CF, et al., eds. Climate Change and Human Health: Risks and Responses. Geneva, Switzerland: World Health Organization; 2003. 63. McMichael AJ, with Woodward A, Muir C. Climate Change and the Health of Nations. New York, NY: Oxford University Press; 2017. 64. Rockström R, Steffen W, Noone K, et al. A safe operating space for humanity. Nature. 2009;461:472–475. 65. Boyden SV. Foreword. In: Butler CD, Dixon J, Capon A, eds. Health of People, Places and Planet: Reflections Based on Tony McMichael’s Four Decades of Contributions to Epidemiology Understanding. Canberra, Australia: ANU Press; 2015:xilv–xlvii. 66. Rodin J. Planetary health: a new discipline in global health. 2015. https//www.rocke fellerfoundation.org/blog/planetary-health-a-new-discipline-in-global-health/. Accessed November 9, 2018.

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67. Brown TM, Cueto M, Fee F. The World Health Organization and the transition from “international” to “global” public health. Am J Public Health. 2006;96:62–72. 68. Packard RM. A History of Global Health: Interventions into the Lives of Other Peoples. Baltimore, MD: Johns Hopkins University Press; 2016. 69. Lakoff A. Two regimes of global health. Humanity. 2010;1(1):59–79. 70. Anderson W. Nowhere to run, rabbit: the Cold-War calculus of disease ecology. Hist Philos Life Sci. 2017;39(2):13. 71.

Grove RH. Green Imperialism: Colonial Expansion, Tropical Island Edens, and the Origins of Environmentalism, 1600–1860. Cambridge, UK: Cambridge University Press; 1995.

72. Robin L. Ecology: a science of empire? In: Griffiths T, Robin L, eds. Ecology and Empire: Environmental History of Settler Societies. Melbourne, Australia: Melbourne University Press; 1997:63–75. 73. Beaglehole R, Bonita R. Development with values: lessons from Bhutan. The Lancet. 2015;385:848.

3 Population, Consumption, Equity, and Rights Robert Engelman, John Bongaarts, and Kristen P. Patterson

Humanity bears no resemblance to any other species before or alongside it, based on the size of its population, its rapid growth, and most particularly its global settlement patterns and use of Earth’s resources. With the scale of our activities and the technologies we have developed and deployed, humanity has radically transformed the planet and life upon it. That environmental transformation is discussed in detail in the next chapter. Here we explore what is known about human population growth and consumption patterns. In 1971, biologist Paul Ehrlich and environmental scientist John P. Holdren developed the I = PAT equation, which stipulates that environmental impacts (I) are the product of population (P) and individual consumption (dubbed affluence, A), mediated by the technologies used for consumption (T).1 Critics have dismissed the I = PAT equation as overly simplistic. The factors interact with each other, and the equation ignores population heterogeneity, the environment’s resilience, potential tipping points, and the impact of time on the interactions. Nonetheless, the I = PAT equation serves an important pedagogical function in conveying that human numbers never act alone but combine with individual behavior and other factors to affect the environment. The relative importance of population and per capita consumption in affecting the environment has long been uncertain, sensitive, and controversial. Which really matters to the environment? Obviously, it is not one or the other but both. To assert otherwise would be akin to suggesting that it is not height but width that determines the area of a rectangle. In isolation a single person’s consumption usually has little impact on the environment. But cumulative consumption, multiplying similar behaviors by millions or 37

38  Planetary Health: Protecting Nature to Protect Ourselves

billions of people making up a population, often has direct and powerful environmental impacts.2 The precise interactions are complex and difficult to pin down and understand, but the effort to do so is nonetheless a worthy one given the ongoing risk to planetary health from climate change and environmental degradation.

Drivers Population The human population is in a constant state of change and probably has been since Homo sapiens emerged some 300,000 years ago. For all but the last 10,000 of those years, our numbers were comparable to those of other large mammals, probably in the single-digit millions, and our footprint was fairly light on the land. Even in small populations relative to today’s, however, humans were the likely agents of extinction for many other species as we learned to hunt effectively and gradually spread around the globe. Prehistoric population sizes may often have been volatile but overall grew quite slowly for most of the hunter–gatherer phase of human existence. They then began a steadier and more rapid climb as agriculture developed 10,000–12,000 years ago. Settled existence probably encouraged higher fertility (numbers of living children born per woman) and higher survival rates of those born, the two engines of population growth. Historical demographers estimate world population in the low hundreds of millions worldwide from the time of the Roman Empire to the late Middle Ages. During the industrial era, which began more than 200 years ago, population growth accelerated because of improvements in food production, sanitation, and health that extended life expectancy. Human numbers grew from 1 billion in 1800 to 2.5 billion in 1950. The most rapid growth occurred after World War II, when world population tripled in size, from about 2.5 billion to 7.7 billion in just seven decades. Since the 1970s, the population has been growing by 1 billion people every 12 years (Figure 3.1). The decline in growth rates since the late 1960s, from 2% annually to about 1%, reflects widespread adoption of effective modern contraception by women and couples wanting to manage the timing and frequency of childbearing. With the growing world population as a base, however, lower rates of growth still lead to an added increment of about 80 million people a year, or roughly 220,000 additional people each day. Past high fertility has resulted in a large population of young people, all but guaranteeing continued growth for some decades even if these young people have an average of just two children each. This “population momentum” powerfully affects future population change. For example, half of Ugandans are under age 15, and most have yet to enter their reproductive years. Small changes in numbers of children, when projected over several decades, generate large differences in total population. One can appreciate the difference that 1 child per woman makes. In Figure 3.1, the UN high variant, in red, is half a child per woman above

Population, Consumption, Equity, and Rights  39

Figure 3.1 Global population, 1950–2100. Source: United Nations, DESA, Population Division. World Population Prospects 2019. Available at http://population.un.org/wpp/, Creative Commons, license CC BY-3.0 IGO.

the median (in yellow); the low variant, in green, is half a child below. The high variant projects 15.6 billion people by 2100—more than twice our current global population— whereas the low variant projects 7.3 billion, a bit lower than current estimated population in 2019 of 7.7 billion people.3 Demographers base their projections on a future with few surprises, and the current expectation is that the global population will reach 10.9 billion in 2100.3 At the regional level, projected trends vary sharply, with population declining after 2050 in Asia and Europe, while North America and especially Africa are expected to continue growing. The high rates of growth in sub-Saharan Africa are projected to propel its population from 1.1 billion today to 3.8 billion in 2100 (Figure 3.2). Other population trends affecting planetary health, which we cannot treat fully here, are the gradual aging of the world’s population and the increasing concentration of humanity in urban areas. In 2015 the estimated median age of humanity—the number that splits population evenly into those younger and those older—was 29.6 years. The median age is projected to increase to 36.2 by 2050, with significant implications for health care needs given higher numbers of older adults.3 Around 2007 urban areas

40  Planetary Health: Protecting Nature to Protect Ourselves

Figure 3.2 Kampala, Uganda. Many of the world’s fastest-growing cities are in Africa, including this one in East-Central Africa. Source: Photo by Carlos Felipe Pardo (Flickr), Creative Commons, license CC BY 2.0

became home to half of humanity, a growth trend likely to continue (Figure 3.3), with potential implications for the environment and human health (discussed in Chapter 13). Scientists generally accept that human population size and growth significantly influence environmental change. A survey of recent peer-reviewed scientific literature by the Worldwatch Institute found frequent assertions that population growth causes or exacerbates environmental problems.4 In 1993, fifty-eight national academies of science jointly stated that “humanity’s ability to deal successfully with its social, economic and environmental problems will require the achievement of zero population growth within the lifetimes of our children.”5 A year later, even the Pontifical Academy of Sciences called “unthinkable” the idea that a global birthrate of much more than two children per woman can long be sustained.6

Individual Consumption In a world marked by near-constant economic growth, the steep rise in global per capita consumption makes a monumental environmental impact when multiplied by the many people who make up humanity’s large and growing population (Figure 3.4). Here, we

Population, Consumption, Equity, and Rights  41

Figure 3.3 Around 2005 the number of people living in cities surpassed those living in rural areas. Most of future population growth is expected to take place in urban environments. Data to 2014 are observed, and subsequent years are projected. Source: United Nations, DESA, Population Division. World Population Prospects 2019. Available at http://population.un.org/wpp/, Creative Commons, license CC BY-3.0 IGO

are referring specifically to categories of consumption that have palpable environmental consequences. Nonrenewable energy and materials must come from the environment and, in some form, return to it. Even renewable energy and materials, such as biomass and fresh water, can cause pollution or be polluted. Furthermore, they can be overused at rates that will limit their availability for future generations. The world economy generates more than $70 trillion a year and grew an estimated 3% in 2017—equivalent to 2% per capita, adjusting for the world’s greater number of people.7 A growth rate of 3% might not sound rapid, but it would double the global economy in 23 years and multiply it sixteen times by the end of this century. Human pressure on the environment might not expand as much, but it is unlikely to remain close to its current— and already probably unsustainable—level. To consider how average per capita consumption contributes to increased human pressure is problematic, however. In an increasingly unequal world, data on per capita consumption can hide considerable variation in the way individuals live. Moreover, data on consumption are more dispersed and less authoritative than those on population. Yet some outlines are clear. Per capita rates of energy, water, food, and material consumption are relatively stable in the developed world, though at high levels in relation to those of developing countries. In rapidly industrializing countries, such as China and India, per capita consumption is comparatively modest but growing fast as poverty declines. In

Figure 3.4 Growth in human population, per capita GDP, and total GDP over time. Since about 1870, human population has increased roughly sevenfold, while per capita GDP has increased by more than 11 times. The combined impact of steep population growth and even steeper growth in per capita GDP explains the extraordinary ballooning of humanity’s total economic (and ecological) footprint. Each dot on the graphs represents a data point. Sources: (A) Max Roser (https://ourworldindata.org/world-population-growth), Creative Commons, license CC BY-SA (B, C) Our World in Data (https://ourworldindata.org/economic-growth), Creative Commons, license CC BY 4.0

Population, Consumption, Equity, and Rights  43

the least developed countries—mostly in sub-Saharan Africa but including Afghanistan, Yemen, and others in Asia—levels and trends in per capita consumption are more varied but generally low and slowly rising. Almost nowhere are important per capita consumption trends in decline, although in some cases technological innovations have restrained the combined impact of population and per capita consumption growth beyond what it would otherwise have been. Few indicators of consumption show greater variance by nation than per capita emissions of carbon dioxide (CO2) from fossil fuels, the largest component of emissions of this most important greenhouse gas (Figure 3.5). In 2014, the latest year for which data are available, the countries with the highest emissions contributed more than a thousand times as much fossil-fuel CO2 per capita as those with the lowest.8 These figures fail to capture significant per capita CO2 emissions from nonfuel sources, such as deforestation, which can be high in low-income countries dependent on biomass for energy and forest removal to expand agricultural land.

Figure 3.5 Per capita CO2 emissions, 2014, in selected countries with populations greater than 100 million people. Source: Carbon Dioxide Information Analysis Center, Environmental Sciences Division, Oak Ridge National Laboratory, Tennessee, at World Bank development indicator database. Available at https://data.worldbank.org/indicator/EN.ATM.CO2E.PC

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Nonetheless, the gap between high and low emitters from fossil fuels is vast and offers perhaps the most dramatic illustration of consumption inequality. The disparity between developed and developing countries isn’t always as expected. (There are considerable disparities within countries, of course, generally correlated with income and wealth, but data on this variability are scarce.) In 2012, for example, per capita emissions of methane, the second most important greenhouse gas, showed little correlation with development or per capita income. Particularly high per capita methane emissions are found in the Central African Republic and Sudan, modest emissions in the United States and most European nations, and low emissions in Italy and Japan.9–11 Globalization complicates comparisons such as these. Cheap transportation and globe-spanning trade networks mean that high-income countries can have global environmental footprints, as when North American beef consumption encourages deforestation in Brazil for cattle raising. Similarly, a nation’s population can be responsible for greenhouse gas emissions well beyond its borders as a result of the “embedded” emissions associated with manufacturing products that they consume but which are produced elsewhere. Consumption by the affluent can also contribute directly to pollution problems for poor communities far away, as when polluting industrial facilities are sited in lowincome neighborhoods or discarded computers end up in developing-country landfills. Compounding the problem, low-income countries typically have less access to important goods and services such as electricity, food, and sanitation. In general, the correlation between higher income and greater per capita consumption holds up in the categories that are most relevant to the environment. Those raising concerns about global levels of per capita consumption often focus on the importance of reducing it among wealthier populations, sometimes calling attention to the multiplication of high consumption rates by large—and in most cases still growing—populations of wealthy people. Consumption by the poor, even at modest levels, can also have implications for the environment and planetary health. Expansion of settlement often occurs at the expense of productive farmland, which can undermine food security. Hunting and expansion of farmland into once-forested land can reduce population sizes and drive the extinction of animals and plants. Waste disposal in the wrong places and at large scales can threaten human health, as well as that of other species. Local and regional shortages of fresh water are becoming increasingly serious. In general, the world’s poorer populations understandably seek to join the wealthier ones in their income and their patterns of consumption. Unlike population projections, there are no statistically robust methods for projecting future rates of per capita consumption of key materials and energy sources. However, Earth is unlikely to produce the energy and material resources that would be necessary for projected twenty-first-century global populations of 8 to 11 billion people to live as North Americans do today. Yet current

Population, Consumption, Equity, and Rights  45

models of economic development both encourage and assume continuation of the highconsumption lifestyles that evolved in the United States and other developed countries over decades of rising affluence. The American dedication to this way of life is well illustrated by President George H.W. Bush’s 1992 statement at a UN environmental summit that “the American way of life is not up for negotiation.”12 Fourteen years later, his son, President George W. Bush, exhorted Americans to “go shopping more” to forestall a looming recession.13 The global spread of consumption-based lifestyles owes much to advertising and entertainment media that have successfully marketed consumerism and stoked aspirations to achieve consumer status. Some cross-cultural research raises the question of the impacts of advertising and consumerism on mental health and happiness,14 a topic explored in more depth in Chapter 11. There may be effects on physical health as well. A 50-year study of a close-knit Italian-American community in Roseto, Pennsylvania found that the immigrant community had lower rates of cardiovascular disease than two neighboring towns when the study began. As Roseto became more Americanized, however, once-strong social bonds weakened, consumerism increased, and rates of cardiovascular disease increased as well. The discrepancy in heart disease at the outset of the study may have been due in part to differences in culture and social cohesion between the three communities.15 As the economies of developing countries grow more rapidly than those of developed ones, the per capita consumption gap is beginning to narrow, at least in national-level comparisons, especially in Asia. Yet income inequality, and presumably also per capita consumption, are increasing in many nations.16 High-end consumers are hardly limited to the developed countries. With individual wealth comes high individual consumption. Rapid but still unequal growth of consumption since World War II, coupled with the likelihood that it will (and in some places should) continue, presents a dilemma that is exacerbated by population growth. How can we stimulate economic development that will alleviate poverty while preserving the environment sufficiently to sustain human and nonhuman life? It is impossible to imagine both of these goals being achieved without significantly reducing the high consumption of energy and materials by the world’s wealthier nations and people, unless science delivers technological breakthroughs that make consumption environmentally benign. Several categories of high-impact consumption are growing in almost all countries. There are now 1.2 billion light-duty vehicles on the planet,17 and sports utility vehicle sales broke records in 2017, with more than a third of all car sales worldwide.18 More people are flying commercially than ever before. The average size of homes—and hence the land occupied, the materials used, and the energy needed to run them—has tended to grow (although this trend may be reversing in especially densely populated cities). Meat consumption and the use of plastic are growing rapidly, especially in developing

46  Planetary Health: Protecting Nature to Protect Ourselves

countries. Per capita material and energy consumption seem to be converging globally at high levels. Convergence near the other end of the scale would be much better for planetary health.

Technology In theory, economic growth could continue indefinitely even if per capita consumption and population reached steady states, especially given the recent tilt toward services and away from manufacturing as a foundation for modern economic growth. But this assumes effective decoupling of gross domestic product (GDP) from growth in throughput, the removal of physical and energy resources from the earth and their displacement in the environment as waste. Current examples of decoupling include increasing the efficiency of automobiles by raising fuel efficiency, encouraging a fleet-shift toward electric or hybrid vehicles, and shifting energy production from carbon-based fuels to such renewable sources as wind and solar power. Despite moves in this direction, the growth in throughput shows few signs of slowing significantly today. Some decoupling has indeed occurred in recent decades, with energy use per dollar of GDP steadily declining worldwide from 1990 to 2015, for example (Figure 3.6).19 So far this trend has failed to compensate for growth in population and per capita consumption, however. The U.S. Energy Information Office projects a 48% increase in world energy consumption from current levels by 2040, with most of that increase provided by carbon-based fuels.20 In 2017, global emissions of CO2 resumed their steady climb after 3 years of relative stability, despite considerable growth in production of renewable energy. A surging global economy continued to rely on carbon-intensive fossil fuels for 81% of energy production. A greater proportion of the world’s population, which included an additional increment of 80 million more people in 2017, gained access to commercial energy.21 Decoupling could in theory evolve into a circular economy, one in which all waste is returned to the economy as resources for more human use, with little or no need to mine or harvest new materials. Unfortunately for planetary health, today’s global economy is far from circular. An estimated 92 billion tons of extracted material resources fed global consumption in 2017, more than three times the 27 billion tons extracted in 1970, according to UN Environment.22 And this figure is projected to double again by midcentury. The agency defines material resources as plants, fossil fuels, metals, and nonmetallic minerals such as sand and gravel. Adding to the complexity of addressing the river of material use is the fact that it is staggeringly unequal. On average, residents of high-income countries use ten times more materials by weight than people do in low-income countries.23 All this suggests that it will be difficult to protect planetary health by decoupling economic growth from population and consumption growth without significant changes in our manufacturing and energy economies.

Population, Consumption, Equity, and Rights  47

Figure 3.6 Energy intensity of global economy, in thousands of British thermal units per U.S. dollar of GDP, 1990–2015. (Energy intensity is the amount of energy required to generate $1 of GDP.) Between 1990 and 2015, energy intensity fell by 28%, 40%, and 32% in countries in the Organization for Economic Cooperation and Development (OECD), non-OECD countries, and the world, respectively. The declining trend reflects energy conservation, energy efficiency, and a transition away from more energy-intensive sectors (e.g., heavy industry and manufacturing) and toward less energy-intensive sectors (e.g., service, software). Accelerating such improvements in energy intensity while rapidly transitioning to carbon-free renewable energy holds promise in allowing productivity gains to continue with much lower environmental impact. Source: EIA. International Energy Outlook 2016. International Energy Statistics and Oxford Economics. Available at https://www.eia.gov/todayinenergy/detail.php?id=27032

Policies Background: Contentious Debate The topic of population growth—and what if anything to do about it—has long been contentious and divisive. Economist Thomas Robert Malthus engendered at least as much opposition as support at the turn of the nineteenth century in arguing that population would inevitably outrun food supply. Until the twentieth century no governments instituted policies explicitly related to population change or distribution, although social and legal sanctions on contraception and abortion indirectly contributed to population increase in many countries. By the early twentieth century the idea of eugenics was beginning to influence government policy in some European and North American countries. The word stems from

48  Planetary Health: Protecting Nature to Protect Ourselves

the Greek for “well-born,” and its advocates pressed for measures to discourage the reproduction of groups deemed inferior and to encourage the reproduction of those deemed superior. In the first half of the century, first some state governments in the United States and later Nazi Germany forcibly sterilized tens of thousands of people in prisons and mental institutions.24 Although eugenics had little direct connection to population control, confusion about the two concepts contributes to continued discomfort with policies aimed at influencing demographic trends. The record of attempted population control in a handful of countries since the midtwentieth century is tainted by their abuses of reproductive rights. The most notorious example is China’s one-child policy. Beginning around 1980, government officials closely monitored the reproductive behavior of the nation’s hundreds of millions of reproductive-age citizens, punished those who exceeded the allowed number of births (generally one per couple), and in some cases forced abortions on offenders of the policy.25 In 1975 and 1976, the government of India sterilized more than 8 million people, mostly men, with many or most of these procedures either directly coerced or strongly incentivized. Both China and India pursued these policies with the explicit intention of bringing down birthrates based on government fears of overpopulation.26 More recently, in Peru from 1996 to 2000, the government of President Alberto Fujimori reportedly oversaw the sterilization of more than 200,000 indigenous women without their consent for the purpose of population control (and implicitly for eugenic population “improvement”).27 Coercive population policies have been pursued to boost flagging population growth rates in at least one case. In Romania, the communist government of Nicolae Ceaus,escu’s banned most abortions and cut off most access to contraception, specifically with the aim of increasing the country’s population from 23 million in 1966 to 30 million in 2000. “Anyone who avoids having children is a deserter,” the dictator declared. The birthrate nearly doubled in response to the policy. Infant mortality also soared, as did illegal abortions, maternal morbidity, and the number of abandoned children raised in state orphanages. The policy ended with Ceaus,escu’s overthrow and execution in 1989.28,29 Mindful of the stigma the phrase carries and its connotation of coercion, most governments and international organizations pursuing policies with impacts on population eschew the term population control and focus instead on improving access to family planning services, expanding educational enrollment and attainment, and increasing gender equality. Even in China, which still formally has policies mandating families of no more than two children per couple, the idea of government pressure to reduce national fertility averages is on the wane. Contemporary population policy is rooted in human rights, individual autonomy, and personal choice, avoiding even the suggestion of fertility targets. Despite its acceptability within the scientific community, the idea that population growth is a major driver of environmental problems is often challenged elsewhere. It may disturb deeply held convictions that humanity is fundamentally good and so more

Population, Consumption, Equity, and Rights  49

humanity is always better. Although attitudes about population defy the conventional political polarity of left and right, it is safe to say that more conservative opponents to efforts to slow population growth tend to celebrate that growth as a spur to innovation, economic growth, and increasing prosperity. Some cite scriptural and religious authority that they contend proscribes modern contraception or sanctifies perpetual human increase. Just as challenging is opposition from some political progressives, especially advocates of women and minority reproductive health and rights. The idea that consumption is the real problem emerges in large part in reaction to a perception by some that population is the real problem. Author Naomi Klein called attention to slowing population growth as one response to climate change “a distraction and moral dead end,” arguing that “the most significant cause of rising [greenhouse gas emissions] is not the reproductive behavior of the poor but the consumer behavior of the rich.”30 The demographic facts laid out in this chapter make clear that this is incomplete reasoning, but it is nonetheless pervasive and influential. We counter such arguments as follows: The direct benefits to individuals and families provide more than sufficient justification for policies that encourage voluntary family planning, education, and women’s empowerment. A fortuitous side benefit to such policies is that they collectively offer some of the best long-term paths to improving human health and achieving environmental sustainability, especially given how daunting the environmental challenges have proven to be. To address population appropriately in the context of human rights and individual choice is to offer each person the means to make some of the most important decisions in life: whether, when, how often, and with whom to become a parent. Successfully reducing per capita consumption, which tends to be more volatile in its rise (and occasional fall) than population, has been much less a focus of government policy considerations. That is a lost opportunity, because reducing per capita consumption could produce environmental benefits more rapidly than the longer process of slowing and eventually ending population growth. Successfully addressing population, which tends to grow over time toward ever higher numbers of consumers, is nonetheless essential to securing for the long term any sustainability gains made by reducing consumption. Lack of awareness of these synergies and their basis in human rights, equity, and personal choice limits powerful options for improving planetary health. Conventional economics lauds consumption as a driver of economic growth, satisfying human needs and desires and raising living standards (see Chapter 15). Most economists dismiss fears that economic growth faces any environmental or natural resource constraints. The fact that the global economy continues to grow even as world population approaches 8 billion people encourages this view. In contrast, a small group of ecological economists argue that environmental constraints on economic activity are real and seek

50  Planetary Health: Protecting Nature to Protect Ourselves

to prioritize economic development aimed at poverty reduction and to harmonize the global economy generally with environmental boundaries.31 Discussion of consumption’s role in human-caused climate change, growing fresh water scarcity, land degradation, and the ongoing loss of biodiversity has picked up in recent years—and has proven next to impossible to extricate from the problem of inequality. In contrast to the often-reaffirmed human right of couples to decide for themselves on the spacing and number of children, there is no agreed-upon “right to consume.” It nonetheless seems obvious that people with lower incomes have as much right to consume as middle-income and wealthier people do, even if they lack the same means. The aspirations of the poor to consume as the rich do are not only understandable, but just. And yet by many estimates a world of today’s population, all consuming as Americans do, could not be sustained without harnessing three additional Earths’ worth of natural resources, according to (admittedly imperfect) calculations of the Global Footprint Network.32 Defying the common assumption that growth in population and consumption is always to be desired, there is little evidence that either type of growth correlates strongly with happiness. Chapter 11 considers this topic in more detail. Given that population growth and consumption patterns are hard to decouple from environmental degradation, ideas for slowing their rates merit consideration. But how do you solve a problem like consumption or the continued growth of the world’s population? Among the biggest obstacles, as we have seen, is that the yawning gulf between the wealthy and the impoverished produces similarly wide gaps in how human beings emit greenhouse gases, consume critical natural resources, encroach on nonhuman habitats, and otherwise influence the environment. All human beings must consume or otherwise transform some things—food, energy, land, and shelter, in particular—and in doing so all have an individual impact on the environment. But the unfairness of grossly unequal wealth and income complicates understanding of human interference in ecological stability and what might be done to lessen that interference. This issue of distributional justice is explored in more depth in Chapter 17. Given the frequent conflation of any population-related policy with population “control,” even scientific discussion of population’s impacts on the environment requires sensitivity to divergent opinions on these topics. For opinions to be widely heard and considered today they must demonstrate respect for equity and recognition of the fundamental dignity and rights of all human beings. This is not difficult. It is now widely understood that fertility and population growth rates fall in direct response to improvements in women’s status, their educational attainment, and their access to contraceptive services. The constructive engagement of men in family planning and support for gender equality amplifies and helps sustain the connection to positive population outcomes. Balancing the importance of both equity and sustainability in considering how people consume tends to elevate the profile of population size in considering human futures

Population, Consumption, Equity, and Rights  51

on a finite planet. If everyone produced precisely equal emissions of greenhouse gases, for example, the amount of per capita emissions of such gases that could sustain a stable climate would decline in direct proportion to the growth of the world’s population. Because per capita emissions are grossly unequal, the importance of population growth is clouded. The challenge is thus to see the roles of population and consumption in planetary health through the fog of an unequal world and to imagine ways of addressing both while shrinking rather than expanding inequality. To be acceptable to the public and to most policymakers, strategies for influencing population change will need to be based entirely on individual choices, human rights, development, and improvements in planetary health and human wellbeing. To the extent that societies can develop truly circular economies, with inefficiency sharply reduced and as much waste as possible cycling back into the economy as resources, the task of shrinking both the amount of consumption and the resource intensiveness of that consumption will be far easier. But absent massive improvement in economic circularity, influencing consumption patterns may require more direct government measures. Even such measures—perhaps taxation of environmental “bads” combined with incentives for environmental “goods”—can be framed to allow individual choice. Motor fuel or air travel may become much more expensive than today, for example, but a person might still choose to spend the extra money. This opens up the possibility that the wealthy will be able to consume what the poor will be unable to afford, implying that reducing consumption will be up to the latter—yet another moral hazard in addressing these questions.

Addressing Consumption Many economists, and even some environmentalists, see reducing consumption as an impossible objective given that so many people desire possessions and the excitement and satisfaction they can confer. Consumption can nourish a sense of belonging to one’s group through like behavior. Competition for status and attractiveness can produce a felt need to consume more or differently than one’s peers.33 As author James B. Twitchell, who had studied advertising and its effects, writes, “Tell me what you buy, and I will tell you what you are and who you want to be.”34 Yet there may be potential to reduce consumption by encouraging deeper wants and desires that can be enjoyed infinitely with no impact on planetary health or the future. Public opinion often leads the leaders, as in the cases of tobacco regulation and fair treatment of gay and transgender people. And there are at least glimmers of hope that public opinion could swivel toward more environmentally sustainable consumption. A sizable literature on consumption and consumerism (defined here as the glorification of consumption for its own sake) has emerged in recent years and offers suggestions for individual, cultural, and political change. Books such as Alan Durning’s How Much Is Enough?35 and Juliet Schor’s True Wealth36 argue that it may be possible to counter the

52  Planetary Health: Protecting Nature to Protect Ourselves

natural inclination to consume excessively by appealing to the widespread longing for high-quality time and rewarding experiences that don’t entail material or energy consumption. These include time with family and friends, physical exercise, artistic appreciation and expression, time in nature, spiritual pursuits such as meditation and engagement with religion, volunteer activities or simply helping others, and community activities that bond neighbors. These ideas are explored in more depth in Chapter 11. Governments need not wait for a dramatic shift in public opinion—or lifestyles—to begin the process of dampening the most damaging types of consumption. Considerable opportunity for modifying these impacts no doubt lies in the third factor of the I = PAT equation: technology. Government can support research on more environmentally benign technologies, and it can encourage adoption of such technologies through regulations (e.g., fuel consumption limits for vehicles). It can encourage educational efforts that bring more minds to address the problem of how populations that are large and affluent can be environmentally sustainable. Governments can also encourage the application of existing technologies—renewable energy, for example—that show promise for massive reductions in human impacts on the environment. Chapter 12 explores the potential for such efforts. “Green taxes” could discourage a range of environmentally damaging consumption. Indeed, the idea of green taxes supplemented with dividends or rebates, often called “feebates” in this context, is designed to incentivize consumption shifts in the way economists prefer, through monetary costs and rewards. Massive shifts in public and policymaker concerns about the state of the environment would be needed, however, to make such policy strategies possible on the needed scale. In line with green taxation are various proposals to restructure fundamental aspects of economic relations globally and within nations, such as designing economic metrics that focus more on human wellbeing and fulfillment and less on monetary value. Among the better-known examples is the Gross National Happiness Index applied in Bhutan. But such metrics, such as green taxation, have yet to spread widely.37 (See Chapters 15 and 16 and policy and Chapter 11 for more on this.) To further discourage excessive consumption, governments could more aggressively regulate advertising, especially to children. They could mandate product labeling of likely impacts on health and the environment. Where environmental risks and damages are extreme, governments could ban or phase out products. Less direct policy changes might also discourage excessive consumption. Schor suggests that shorter work weeks would make it easier for workers to spend more time in rewarding, noneconomic pursuits. This could make it less likely that working people would spend lavishly in response to intensive working lives that require them to trade most of their available time for income. The strategy is speculative, however. Certainly, those working fewer hours have less money to spend than they would otherwise. But how they would spend their free time and whether they would actually spend less money

Population, Consumption, Equity, and Rights  53

remains unclear. More government investment in preservation of natural areas along with reductions or abolition of fees required to enjoy them might also tempt at least some people away from environmentally problematic consumption. Ultimately, what is needed to curb consumption are strategies that produce collective and global benefits based on offering people something they actually want: options and choices that allow them to better manage their own lives and improve their health and quality of life. That is the approach supported by those who hope that world population will stabilize or slowly decline as individuals and couples make healthy and effective childbearing decisions.

Addressing Population Growth Between the late 1960s and 2015, according to UN estimates, world fertility, the average number of live births per woman, fell by almost 50%, from nearly 5 to 2.5.38 As of 2019, women from ninety-two different countries have an average of fewer than 2.1 children each, absent net immigration. These fertility rates, if universal, would lead eventually to an end to population growth.38 Despite significant increases in child survival and life expectancy over the same period, the reduction in the size of human families cut the rate of world population growth almost in half by 2015, from 2% annually in 1970 to slightly more than 1% in 2019. Had that growth rate instead stayed steady, the world would today be home to almost 9.6 billion people.* In addition to the negative health impacts associated with high fertility, it would be much more challenging under that hypothetical scenario to address global warming and other environmental problems undermining human and ecological health. A variety of positive social forces—each beneficial in its own right—has contributed to the decline in fertility and the slowing of human population growth in recent decades. These include rising educational attainment, particularly for girls, reductions in infant and child mortality, and improved status of and economic opportunities for women. In addition, many governments have invested in voluntary family planning programs. The proportional contribution of each is difficult to disentangle and is subject to dispute among demographers and economists. Nonetheless, there are some estimates of impacts of specific interventions. In a study of 18 developing countries, for example, the World Bank recently estimated that universal secondary education could reduce total fertility by one third.39 A recent examination of family planning programs in a range of developing countries found that strong programs could increase contraceptive prevalence from 20% to 30% and reduce total fertility rates by an average of 1.5 children.40 Whatever the relative impact of the diverse drivers of fertility decline, an essential component has been expanded access to and use of safe and effective methods of *Co-author Engelman’s calculation based on constant growth rate from 1970 population.

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contraception. Without these, women and couples would not have been able to put their reproductive choices into effect. These childbearing choices of hundreds of millions of couples since 1970 have meant that far fewer human beings are now consuming energy and materials than would have been the case had these couples chosen differently—or not been able to choose. (And, in the bargain, the choices have saved the lives of uncounted children and women, given the close connection between early and frequent pregnancy and infant and maternal mortality.) For the objective of slowing population growth there is no conflict between effectiveness and ethics: Expanding the reach of family planning services, education (especially secondary), and economic and related opportunities for women would on their own achieve more than any conceivable efforts by governments to control population by mandating or incentivizing lower fertility. Some economists question the view that strong family planning programs are needed for fertility decline. Conventional economic theory tends to view childbearing as a utility-maximizing decision by parents, comparable to the purchase of a new car or a refrigerator. Many economists believe that the economic development of the last third of the twentieth century simply resulted in parents finding less utility in large families. Where family size remains high, parents simply continue to find large families economically optimal, according to this line of thinking. By implication it matters little whether family planning programs are available or not; what is decisive is parents’ interest in having or not having more children.41 However, both logic and data undermine this reasoning. People do not engage in sex only when seeking to procreate, nor can they control on their own when sex will lead to pregnancy and when it will not. By the latest estimates, 44% of pregnancies were unintentional worldwide from 2010 to 2014.42 What sexually active couples face is more akin to a new car or refrigerator arriving at their door every couple of years unless they take active measures to prevent such deliveries. Most people do endeavor to manage the timing and frequency of pregnancy—they take active preventive measures for most of the years (typically considered from age 15 to 49 for women) in which they are capable of conceiving and bearing a child. Nearly two thirds (64%) of women worldwide practice contraception, most relying on effective modern contraceptives. This prevalence of contraceptive use among reproductive-age women has nearly doubled since 1970, when the proportion was 35%.43 Many of the 36% of women not using contraception either are not sexually active, are pregnant, or are trying to become pregnant, and the percentage of sexually active women seeking to avoid mistimed or unwanted pregnancy who are using contraception is closer to 75%. The halving of family size worldwide since the mid-twentieth century has been among the most pervasive social revolutions in human history. Although the spread of voluntary family planning services was scarcely the sole cause, it was certainly essential. This spread was aided by foundations, governments, corporations, and nongovernment reproductive

Population, Consumption, Equity, and Rights  55

health organizations from the 1950s onward. But family size never would have plummeted as it did unless most people wanted to have fewer children than their parents and grandparents. No doubt, economic development, urbanization, mass media, and especially increasing educational attainment by women and men also contributed to the fall of both desired and actual fertility after 1970. The tight linkage between the level of schooling women complete and subsequent fertility is well documented in almost every population studied. In Africa, women with no education average 5.4 children each, according to the International Institute for Applied Systems Analysis.44 Women who have completed primary school average 4.3 live births, and for those who complete secondary school, fertility is 2.7. Among women with some higher education, the average falls to 2.2 births each—below replacement fertility in Africa because, unfortunately, significant proportions of children still perish before reaching reproductive age.45 On average, researchers have found, each year of a girl’s education reduces her fertility by 0.3 to 0.5 children.46 Education alone is insufficient to drive fertility down, however. After all, even women with doctorate degrees cannot make safe and effective contraceptives on their own and must have access to services. Despite the progress in effective personal management of childbearing and the expansion of family planning programs in recent decades, surveys indicate continuing high levels of unintended pregnancy in every region of the world, although rates have dropped somewhat in recent years.42 An estimated 214 million women in developing countries alone would prefer not to be pregnant but are not using modern contraception.47 An estimated 100 million of the 227 million pregnancies that occur each year are either mistimed or unwanted, according to the Guttmacher Institute, a leading advocacy-oriented reproductive health think tank.48 Roughly half of these unintended pregnancies end in abortion, and many of the rest miscarry, proportions that speak to the mental and physical toll of unintended pregnancy. Demographically, it’s likely that between 35 and 45 million births annually could have been prevented or postponed to a desired time if couples had access to effective contraception. (Births that occur later in a woman’s reproductive years contribute to slower population growth through a stretching out of generational succession, although less powerfully than births averted altogether.) Proportions of unwanted pregnancy are especially high in Latin America and in many developing countries elsewhere. Even in the United States, despite a sophisticated (and costly) health care sector, nearly half of pregnancies are unintended. Perhaps even more surprising, countries with low fertility in Europe have significant levels of unintended pregnancy and abortion, the Guttmacher Institute finds, suggesting that if all pregnancies were wanted and successfully timed by both partners, fertility would fall further still in these countries based on parents’ reproductive intentions. The conclusion is that simply helping all people achieve their parenting intentions in safety and health would slow the growth of population significantly and possibly

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dramatically. (Helping infertile couples bear children is an important reproductive health objective in its own right and is unlikely to have much overall impact on population-wide fertility or growth.) Those who work in family planning and reproductive health have long understood the catalytic and multisided benefits of expanded access and use of family planning (Box 3.1). But the fact remains much less understood among policymakers, journalists, and the general public. “Unlike many other steps that could be taken to reduce the rate of environmental changes, reductions in rates of population growth can be accomplished through voluntary measures,” the Royal Society of London and the U.S. National Academy of Science wrote in a joint statement on population more than a quarter century ago. “Surveys . . . repeatedly reveal large amounts of unwanted childbearing. By providing people with the means to control their own fertility, family planning programs have major possibilities to reduce rates of population growth and hence to arrest environmental degradation.”49 Copious evidence from such developing countries as Bangladesh (Box 3.2), Iran, and Thailand demonstrate the power of offering optimal reproductive services to all who seek them, of whatever age. On a smaller scale, some wildlife conservation and natural resource management projects around the world facilitate access to family planning services (Box 3.3), with comparable positive outcomes. One such integrated population, health, and natural resource management effort around Lake Victoria in Africa is described in depth in Planetary Health Case Studies: An Anthology of Solutions (https://islandpress.org/books/ planetary-health). Critical to good reproductive health services is the provision of a variety of contraceptive methods that include long-acting reversible contraceptives and permanent ones for both sexes. Fertility typically falls rapidly when governments or organizations offer programs that comprehensively address the sexual and reproductive health needs of adolescents and adults. Such programs aim to help individuals and couples achieve their own childbearing intentions in good health. Without exerting pressure to achieve any specific family size, the result over time is universally smaller families based on those personal intentions. Dramatic economic development is not necessary for dramatic fertility declines. In fact, the reverse sequence has been more common, with strong economic growth following drops in fertility. This reflects, in part, a phenomenon known as the demographic dividend, an economic boost that typically follows closely on fertility decline if governments and societies can take advantage of the resulting increase in the proportion of working adults compared with dependent children. When governments and civil society invest these dividends in human capital—education and health care—the “interest” can compound dramatically. Despite the progress of the last half century, many barriers impede the progress of family planning around the world. Sexuality, contraception, and abortion remain sensitive

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Box 3.1. Why Family Planning? Robert Engelman, John Bongaarts, Kristen P. Patterson Though often discussed in relation to slowing population growth or promoting the demographic dividend, family planning also contributes to planetary health through its more immediate benefits to individuals and their families. The voluntary use of contraception lowers the risk of health problems for mothers and children related to pregnancy and birth, raises maternal and child survival, facilitates personal autonomy, and promotes the quality of life. Most people want to be free to express their sexuality when and with whom they choose, without the constant fear of unintentionally conceiving and bearing a child. By managing healthy reproduction on their own terms, people expand the range of choices they can make and the life opportunities of which they can take advantage. Outside China, which has been loosening its regulation of reproduction in recent years, childbearing is fundamentally a personal decision, not a community or national one. As a matter of good practice, family planning providers focus on the individual and family benefits of contraception rather than the larger issue of population growth. On that basis, using contraception makes sense for sexually active people at risk of conception and pregnancy in much the same way as other behaviors that promote health and happiness. As one means of quantifying some of these direct benefits, the Guttmacher Institute estimated that each $10 million in U.S. assistance for family planning and reproductive health (which totaled a bit more than $600 million in fiscal 2018) in developing countries: • Provides contraceptive services and supplies to 416,000 women and couples • Prevents 124,000 unintended pregnancies and through that 54,000 unplanned births • Prevents 53,000 abortions, 35,000 of which would have been provided in unsafe conditions • Prevents the deaths of 240 women in pregnancy or childbirth.a Contraception is especially important in preventing the deaths of infants and young children. Birth intervals of less than two years, which are common among sexually active women not using effective contraception, greatly raise the risk of such deaths. The likelihood of maternal survival rises with longer birth intervals and fewer unintended pregnancies. More time for recuperation from pregnancy and childbirth and for breastfeeding also benefits the mother’s health and improves the survival, health, and development of children. Contraception also prevents high-risk pregnancies among adolescents aged 15 to 19 (who are twice as likely to die from complications of pregnancy or

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childbirth as women aged 20 to 24), women older than 35, and all women who have already given birth often or have had closely spaced pregnancies.b Contraception also prevents abortions, 45% of which around the world occur in unsafe conditions. In some least developed countries, 40% of such unsafe abortions result in complications that require medical care, with some 6.9 million women treated annually in developing countries as a whole.c Careful use of male and female condoms also prevents sexually transmitted infections such as HIV/AIDS. The issue of intimate partner violence can complicate the use of contraception, however. An estimated 30% of women worldwide who have ever been in a sexual relationship have experienced violence at the hands of a current or former partner.d Discovery that a woman is using contraception sometimes triggers such violence, which can limit her method choice or decision to continue use.e Beyond the obvious health benefits of using contraception lies one that cannot be fully captured in a clinic or by a ministry of health. Through safe and effective use of the right contraceptive method for each user, people can balance their personal intentions and ambitions, without fear that an unintended conception will derail or limit plans and dreams. This is especially important for women and for gender equality generally. Any hopes for the latter rest on women’s ability to possess a capacity that men do not need to ask for: to have sex when desired, free of the fear of unintended pregnancy. References a. Guttmacher Institute. Just the numbers: the impact of U.S. international family planning assistance. 2018. https://www.guttmacher.org/article/2018/04/just-numbers -impact-us-international-family-planning-assistance. Accessed September 2019. b. Smith R, Ashford L, Gribble J, Clifton D. Family Planning Saves Lives. 4th ed. Washington, DC: Population Reference Bureau; 2009. Available at: https://www.prb.org /wp-content/uploads/2010/10/familyplanningsaveslives.pdf. c. Singh S, Remez L, Sedgh G, Kwok L, Onda T. Abortion Worldwide 2017: Uneven Progress and Unequal Access. New York, NY: Guttmacher Institute; 2018. Available at: https: //www.guttmacher.org/report/abortion-worldwide-2017. d. World Health Organization: Department of Reproductive Health and Research, London School of Hygiene and Tropical Medicine, Council SAMR. Global and Regional Estimates of Violence Against Women: Prevalence and Health Effects of Intimate Partner Violence and Non-Partner Sexual Violence. Geneva, Switzerland: World Health Organization; 2013. Available at: https://www.who.int/reproductivehealth/publications /violence/9789241564625/en/. e. Gilles K. Intimate Partner Violence and Family Planning: Opportunities for Action. Washington, DC: Population Reference Bureau; July 2015. Available at: https://assets.prb .org/pdf15/intimate-partner-violence-fp-brief.pdf.

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Box 3.2. A Family Planning Case Study: Pakistan and Bangladesh John Bongaarts Over the past half century many governments in developing countries have implemented family planning programs to provide access to and information about contraception methods. The initiation of these programs is usually followed by substantial increases in contraceptive use and declines in fertility. Unfortunately, it is difficult to determine the exact role of the family planning programs from these trends because it is likely that contraceptive use would have risen somewhat even in the absence of the program. This fact has made the estimation of net program impact difficult and controversial. The gold standard for evaluating the impact of health interventions is to conduct experiments. Unfortunately, few large-scale controlled experiments have been conducted to assess family planning programs because they are expensive and take a long time to complete. The largest and most influential of these experiments—the Family Planning and Health Services Project (FPHSP)—began in the late 1970s in Matlab, Bangladesh. At that time, Bangladesh was one of the poorest and most highly agricultural countries in the world, and there was widespread skepticism that family planning would be accepted in such a traditional society. The FPHSP divided the rural Matlab district (population of 173,000 in 1977) into experimental and control areas of approximately equal size. The control area received the same (minimal) services as the rest of the country, whereas in the experimental area comprehensive high-quality family planning services were provided, aimed at reducing the costs (monetary, social, psychological, and health) of adopting contraception. The experimental area provided free services and supplies of a range of methods (pills, condoms, injectables, IUDs, and sterilization), home visits by well-educated female family planning workers, regular follow-up to address health concerns, comprehensive multimedia communication, and menstrual regulation* services. Outreach to husbands, leaders of household groups, and religious leaders addressed potential social and familial objections from men. The impact of these intensive services on reproductive behavior was large and immediate. Within a year from the start of the program, the proportion of women using contraception in the experimental area rose from 5% to 28%. In contrast, little change *Menstrual regulation is a procedure that uses vacuum aspiration or a combination of mifepristone and misoprostol to induce menstruation when it is delayed for a short duration. Abortion is illegal in Bangladesh.

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occurred in the control area or in the rest of Bangladesh during the first few years. The rise in contraceptive prevalence in the experimental area led to a decline in fertility of about 25% below the level in the control area.a The Matlab experiment demonstrated that family planning programs can succeed even in traditional societies. The success of this program led the government of Bangladesh to adopt the Matlab model as its national family planning strategy. Figure 3.2.1 plots trends in fertility from 1970 to 2010 for Bangladesh and Pakistan. At the end of the 1970s the two countries had nearly the same high fertility of 6.8 births per woman, but trends diverged in subsequent decades. By the late 1990s fertility in Bangladesh had declined to 3.4 births per woman, while in Pakistan fertility still stood at 5.0. This difference in fertility was maintained, with Bangladesh reaching near replacement fertility of 2.2 births per woman in 2010–2015, a remarkably low level for such a poor country.b

Figure 3.2.1 Fertility estimates in Bangladesh and Pakistan since their separation in 1971.

The contrasting fertility trends in these two countries can plausibly be attributed to differences in their family planning programs. Pakistan’s program has been weak, lacking government funds and commitment, although it has gradually improved over time. In contrast, Bangladesh has implemented one of the world’s most effective voluntary family planning programs, using the experience and lessons from the Matlab experiment. Fertility and population trends are also affected by the level of development and social and cultural factors, but these are unlikely to be an important explanation for the different country trajectories. Development levels, as measured by the Human Development

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Index, are nearly the same for Bangladesh and Pakistan.c Moreover, the two countries were united as one country from 1947 until Bangladesh was established after a civil war in 1971; they therefore share common cultural, religious, and government traditions. Pakistan’s neglect of family planning in the 1970s and 1980s led to much more rapid population growth than in Bangladesh (Figure 3.2.2). In 1980, the populations of the two countries were about the same size, but by 2050 Pakistan’s population is projected to be 50% larger than Bangladesh’s (307 compared with 202 million) and by 2100 Pakistan’s population is projected to be twice that of Bangladesh (352 compared with 174 million).b When populations are growing rapidly, delays in the implementation of family planning programs and in the fertility decline associated with them have major implications for future demographic trends and associated health and environmental impacts.

Figure 3.2.2 Population estimates (solid lines) and projections (dashed lines) in Bangladesh and Pakistan since their separation in 1971.

References a. Cleland J, Phillips J, Amin S, Kamal G. The Determinants of Reproductive Change in Bangladesh: Success in a Challenging Environment. Washington, DC: The World Bank; 1994. b. United Nations Department of Economic and Social Affairs: Population Division. World Population Prospects: The 2017 Revision. New York, NY: United Nations Department of Economic and Social Affairs, Population Division; 2017. c. United Nations Development Programme. The Human Development Report 2016. New York, NY: United Nations Development Programme; 2016.

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Box 3.3. Building Resilience through a Holistic Population, Health, and Environment Approach Kristen P. Patterson Integrated development programming to address both social and environmental challenges dates back at least to the mid-1980s. At that time, wildlife conservation groups began linking their mission—saving wildlife—with the economic development of rural communities adjacent to national parks and other protected areas in developing countries rich in biological diversity. Beginning in the late 1990s, based on rural communities’ requests for health services, a new approach was developed, which added reproductive health and gender components to conservation projects, and the concept of Population, Health, and Environment (PHE) was born.a The aim: Work collaboratively with communities to simultaneously improve access to primary health care services, including family planning and reproductive health, while also helping people develop more environmentally sustainable livelihoods and, in the process, conserve the critical ecosystems and natural resources on which communities depend. Assessments of PHE projects show that integrating such seemingly disparate services can be more effective and efficient than focusing on single sectors. Stated benefits includeb • Increased access to and use of contraceptives by improving access to family planning in development projects • Improved maternal and child health outcomes, including lower fertility, especially in remote and underserved areas • Improvements in environment indicators beyond outcomes achieved in single-sector projects • Acceleration of benefits through greater community enthusiasm and rapid mobilization of effort • Improved outcomes in natural resource management when linked to health, livelihood, and microcredit components • Greater involvement of men in family planning and of women in conservation and natural resource management • Time and cost savings both for implementers and communities In addition, recent research has shown evidence of value-added outcomes, including changes in gender roles and time savings and increased income for women.c

Population, Consumption, Equity, and Rights  63

Documented gains in contraceptive use in PHE projects are noteworthy because the remote and often impoverished communities served are often the hardest to reach with health services. As in much of the world, large proportions of women in such communities express the desire to plan and space their childbearing, and in many cases PHE projects make that possible for the first time. Blue Ventures, a marine conservation organization operating in southwestern Madagascar, saw the prevalence of modern contraceptive use rise from 10% of women before the project began in 2007 to 59% in 2013 after they integrated reproductive health initiatives into their conservation activities. As contraceptive use rose, birthrates declined, with general fertility (births per average woman per year) falling by half.d A PHE project supported by PATH Foundation Philippines reported similar results and found that the use of contraception was generally higher in communities in which reproductive health services were combined with natural resource management services than in similar communities where only single-sector services were offered.e In Ethiopia in the mid-2000s, the Guraghe People’s Self-Help Development Organization increased the number of men who expressed support for family planning from 7% to 30%.f The cross-disciplinary nature of integration and the breadth and diverse scale of PHE interventions make monitoring and evaluation challenging, although significant progress has been made in the last 5 years. An analysis of evidence of impact from thirtyfive PHE projects implemented from 2005 to 2015 found that integrating reproductive health and environmental conservation in developing-world communities catalyzes improvements in both areas that otherwise would not occur.g More recent research efforts have focused on defining and measuring the contributions of PHE projects—particularly the family planning component—for building resilience among rural households.h Resilience is the capacity of systems and communities to withstand hazardous change through learning, flexibility, and innovative adaptation, and it is increasingly becoming the lens through which sustainable development can be achieved.i Household surveys in 2016 in one project in western Tanzania found a significant association between family planning and health care access and multiple components of resilience.j The study provided evidence that improving access to family planning and maternal and child health services as part of PHE projects can build household resilience as a buffer against the impacts of climate change and other environmental stressors. Further uptake of the PHE approach could have positive implications for achievement of the sustainable development agenda, particularly for rural communities in developing countries most affected by poor health and environmental degradation.

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References a. Edmond J, Viernes M Jr., Send B, Zatovonirina N. Healthy Families Healthy Forests: Improving Human Health and Biodiversity Conservation. Arlington, VA: Conservation International Foundation; 2009. b. Pielemeier J. Review of population–health–environment programs supported by the Packard Foundation and USAID. 2005. http://www.ehproject.org/PDF/phe/ll-packard2 .pdf. c. Sellers S. Does doing more result in doing better? Exploring synergies in an integrated population, health and environment project in East Africa. Environ Conservation. 2019;46(1):43–51. d. Dr. Vik Mohan, medical director of Blue Ventures, to author Engelman, personal communication, May 14, 2018. f. D’Agnes L, D’Agnes H, Schwartz JB, Amarillo M, Castro J. Integrated management of coastal resources and human health yields added value: a comparative study in Palawan (Philippines). Environ Conservation. 2010;37(4):398–409. g. Yavinsky R, Lamere C, Patterson K, Bremner J. The Impact of Population, Health, and Environment Projects: A Synthesis of Evidence (Working paper). Washington, DC: Population Council, The Evidence Project; 2015. h. Bremner J, Patterson K, Yavinsky R. Building Resilience through Family Planning: A Transformative Approach for Women, Families, and Communities. Washington, DC: Population Reference Bureau; August 2015. i. Hardee K, Patterson K, Schenk-Fontaine A, et al. Family Planning and resilience: associations found in a population, health and environment (PHE) project in western Tanzania. Popul Environ. 2018;40(2):204–238. j. Patterson K. Changes in Household Well Being and Resilience: The Role of Population, Family Planning and Reproductive Health in the Tuungane Project. Washington, DC: Population Council, The Evidence Project; March 2018.

and often taboo topics in many parts of the world. Reproductive health programs are still afforded low priority in most countries, including those where incomes are low and population growth rates often the highest. Health care facilities may be few and far between. Poorly paid staff may lack the time and training to attend to the needs of clients for careful counseling and personally tailored services, including for the right contraceptive method for individual needs. Assistance from foundation and government donors in industrialized countries has been critical to the development and spread of programs in nonindustrialized ones. Aid from wealthy countries for family planning in poorer ones is modest: Organisation for Economic Co-operation and Development member countries currently spend only 1% of their overseas development assistance on it.50 And this assistance is vulnerable to shifting political winds and whims. In the United States, for example, recent Republican administrations have limited reproductive health funding

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and prohibited assistance to nongovernment organizations in foreign countries that provide or offer information on abortion. The Guttmacher Institute estimates that the world’s governments and consumers spend about $1 per person per year on modern contraception, or about $6.3 billion. Meeting all women’s needs for modern contraception in developing countries would cost about twice that amount, but it would also save $1.79 per person that is otherwise spent on maternal and child care.51 (Comparable data on the costs of contraception in industrialized countries, much of it covered privately, are not available.) Averted unintended births also reduce future expenditures on education and infrastructure. In general, global spending on family planning has been stagnant so far in this century. In one positive sign, in 2012 the Bill & Melinda Gates Foundation and the government of the United Kingdom initiated a major project designed to boost global investment in family planning in low-income countries.52 Beyond the tepid institutional support that family planning services often must survive on, people sometimes must overcome barriers in their communities and families to plan pregnancies. Surveys indicate that fear of side effects of contraceptive use is among the most common reasons cited by women who would prefer to avoid pregnancy but are taking no steps to do so. Opposition to family planning by sexual partners (sometimes expressed violently), in-laws, or peers can discourage contraceptive use. Improving women’s autonomy and preventing intimate partner violence are vital for improving family planning uptake, as well as for their own sake. Religious opposition may also limit contraceptive access, as religious leaders more effectively browbeat timid government policymakers than they do individuals anxious to plan their families. The question of whether and how family planning programs should take on these barriers is a sensitive one. The concept of raising demand for family planning, as opposed to simply meeting existing demand through improving access, strikes some in family planning as having too much potential for heavy-handed persuasion or even coercion of women and couples to have fewer children than they want. In countries where desired family size remains large and the health, environmental, and social strains of rapid population growth are significant, however, the question of how to motivate greater use of family planning cannot easily be dismissed. In such settings, program efforts to reduce social, economic and other barriers to contraceptive use among women who want to avoid pregnancy should be encouraged. Evidence is strong that just the availability of voluntary family planning programs tends to increase demand for the services as the use of contraception becomes more acceptable in traditional societies. Encouraging girls in particular to advance their education clearly also raises demand, although concomitant investments in schools are needed in many countries in order to do this. Comprehensive sex education tends to raise both the demand for and the use of contraception while

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contributing to delays in sexual initiation. This is especially true when sex education accompanies reproductive health services that students can learn about and even gain access to in school. Some groups have demonstrated significant improvements in the uptake of family planning among listeners to fictional radio programs that incorporate reproductive health and gender equality messages in their storylines.53

Conclusion: Integrating Population and Consumption Ultimately, finding approaches to planetary health that address both per capita consumption and population may show the most promise. Given the tight interconnectedness of the two drivers, it may be best to see them as coequal challenges. At the very least, they are simply two sides of a single problem: the increasingly risky impact of human activity on the ecosystems and natural resources on which human health depends. Beyond the narrow possibility that technological advances might someday fully decouple growing human activity from environmental change lies a landscape of options for consumption and population that deserve exploration for the sake of a healthy human and planetary future. Consider, for example, the potential impact of combining age-appropriate environmental, demographic, and sex education throughout school curricula; green taxation balanced by distributed dividends to all; and strong public support for reproductive health services. Existing research doesn’t allow us to quantify precisely what each action might accomplish and when or how they might magnify their impacts when applied together. But logic and evidence suggest an important influence of each on population and consumption. Policies instituting such actions will require firm political will and conviction at every level of government and society. Interest from journalists and expert analysts in many fields and the support of general public are essential for sustained progress. Individuals can promote tolerance and acceptance of decisions to forgo birth, to adopt children, or not to have children at all. People of faith can consider the spiritual benefits of better planetary stewardship through responsible consumption and reproduction. All who care about these issues will need to be vigilant against coercive measures related to childbearing and consumer choices and heavy-handed persuasion that denigrates or dehumanizes individuals. By the same token, to assume it is never appropriate to encourage sustainable reproduction and consumption would be to deny individuals’ intelligence and their capacity to weigh information and make decisions freely and responsibly for their own lives, families, communities, species, and planet. A multipronged strategy that integrates education, sound policies, and high-quality health services—all while guaranteeing the rights and respecting the dignity of all people—could dramatically accelerate the transition to truly sustainable levels of human population and consumption. The basis would be the choices people make in directing their own lives. The outcome could be health, happiness, meaning, and satisfaction without limits on a planet that will never grow in size.

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Authors Robert Engelman, MSc is a writer and researcher who has authored a book on population, the environment, family planning, and the lives of women. A former president of the Worldwatch Institute, an environmental think tank, Engelman was a co-founder and first board chair of the Center for a New American Dream, a nonprofit promoting sustainable consumption. He now serves as senior fellow at the Population Institute in Washington, D.C. John Bongaarts, PhD is vice president and distinguished scholar of the Population Council. His research has focused on a range of population and health issues, including population projections, determinants of fertility and mortality trends, population policy options in both the developed and developing world, and population and environment. He is a member of the U.S. National Academy of Sciences and the Royal Dutch Academy of Sciences and is a laureate of the International Union for the Scientific Study of Population. Kristen P. Patterson, MPH, MSc is the program director of People, Health, Planet with the Population Reference Bureau. Kristen worked for the Africa Region of The Nature Conservancy for 6 years, where she helped launch an integrated population, health, and environment project, Tuungane, in western Tanzania. She spent 2 years in Madagascar as a USAID Population–Environment Fellow and has conducted research in Niger on farmer– herder conflict resolution.

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10. United Nations Population Division. WPP POP_F01_TOTAL POPULATION_BOTH_ SEXES. World Population Prospects: The 2019 Revision. New York, NY: United Nations Population Division; 2019. 11. World Development Indicators. Methane emissions (kt of CO2 equivalent). The World Bank; 2019. https://data.worldbank.org/indicator/EN.ATM.METH.KT.CE?view=chart. 12. Deen T. U.S. lifestyle is not up for negotiation. Inter Press Service. 2012. http://www .ipsnews.net/2012/05/us-lifestyle-is-not-up-for-negotiation/. Accessed July 2019. 13. C-SPAN. Clip of presidential news conference: Bush shopping quote. 2001. https: //www.c-span.org/video/?c4552776/bush-shopping-quote. Accessed July 2019. 14. Kasser T. Values and the next generation. Solutions. 2012;3(3):119–124. 15. Egolf B, Lasker J, Wolf S, Potvin L. The Roseto effect: a 50-year comparison of mortality rates. Am J Public Health. 1992;82(8):1089–1092. 16. Qureshi Z. Trends in income inequality: global, inter-country, and within countries. 2017. https://www.brookings.edu/wp-content/uploads/2017/12/global-inequality.pdf 17. Voelcker J. 1.2 billion vehicles on world’s roads now, 2 billion by 2035: report. Green Car Rep. 2014. https://www.greencarreports.com/news/1093560_1-2-billion -vehicles-on-worlds-roads-now-2-billion-by-2035-report. Accessed July 2019. 18. Del Bello L. SUV sales rise worldwide, despite their effect on climate. Futurism. 2018. https://futurism.com/suv-sales-rise-worldwide-despite-effect-climate. Accessed July 2019. 19. Kahan A. Global energy intensity continues to decline. EIA: Today in Energy. 2016 (July 12). https://www.eia.gov/todayinenergy/detail.php?id=27032. 20.

Doman L. EIA projects 48% increase in world energy consumption by 2040. EIA: Today in Energy. 2016. https://www.eia.gov/todayinenergy/detail.php?id=26212. Accessed July 2019.

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22. International Resource Panel. Global Resources Outlook 2019: Natural Resources for the Future We Want. Nairobi, Kenya: United Nations Environment Program; 2019. Available at: https://www.resourcepanel.org/reports/global-resources-outlook. 23. International Resource Panel. Assessing Global Resource Use: A Systems Approach to Resource Efficiency and Pollution Reduction. Nairobi, Kenya: United Nations Environment Program; 2017. Available at: https://www.resourcepanel.org/reports/assessing -global-resource-use. 24. United States Holocaust Memorial Museum. Forced sterilization. https://www .ushmm.org/learn/students/learning-materials-and-resources/mentally-and-physically -handicapped-victims-of-the-nazi-era/forced-sterilization. Accessed July 2019.

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25. Feng W, Cai Y, Gu B. Population, policy, and politics: how will history judge China’s one-child policy? Popul Dev Rev. 2012;38:115–129. 26. Harkavy O, Roy K. Emergence of the Indian National Family Planning Program. In: Robinson WC, Ross JA, eds. The Global Family Planning Revolution: Three Decades of Population Policies and Programs. Washington, DC: The World Bank; 2007. 27.

Lizarzaburu J. Forced sterilisation haunts Peruvian women decades on. BBC News. 2015. https://www.bbc.com/news/world-latin-america-34855804. Accessed July 2019.

28. Breslau K. Overplanned parenthood: Ceausescu’s cruel law. Newsweek. 1990:35. http: //www.ceausescu.org/ceausescu_texts/overplanned_parenthood.htm. Accessed July 2019. 29. Bradatan C, Firebaugh G. History, population policies, and fertility decline in Eastern Europe: a case study. J Fam Hist. 2007;32(2):179–192. 30. Klein N. This Changes Everything: Capitalism vs. the Climate. New York, NY: Simon and Shuster; 2014:114n. 31. International Society for Ecological Economics. The ISEE. 2019. http://www.isecoeco.org/. 32. McDonald C. How many Earths do we need? BBC News. 2015. https://www.bbc.com /news/magazine-33133712. Accessed July 2019. 33. Miller D. Consumption and Its Consequences. Cambridge, UK: Polity; 2012. 34. Twitchell JB. Lead Us into Temptation: The Triumph of American Materialism. New York, NY: Columbia University Press; 2000. 35.

Durning A. How Much Is Enough? The Consumer Society and the Future of the Earth. Washington, DC: Worldwatch Institute; 1992.

36. Schor J. True Wealth: How and Why Millions of Americans Are Creating a Time-Rich, Ecologically Light, Small-Scale, High-Satisfaction Economy. New York, NY: Penguin; 2011. 37. Oxford Poverty & Human Development Initiative. Bhutan’s Gross National Happiness Index. n.d. https://ophi.org.uk/policy/national-policy/gross-national-happinessindex/. Accessed July 2019. 38. United Nations Population Division. file FERT/4: Total fertility by region, subregion and country, 1950–2100. In: World Population Prospects: The 2019 Revision. New York, NY: United Nations Population Division; 2019. 39. Wodon QT, Montenegro CE, Nguyen H, Onagoruwa AO. Missed Opportunities: The High Cost of Not Educating Girls. Washington, DC: World Bank Group; 2018. https://www.worldbank.org/en/news/factsheet/2018/07/11/missed-opportunities -the-high-cost-of-not-educating-girls. 40. Bongaarts J. The impact of family planning programs on unmet need and demand for contraception. stud Fam Plann. 2014;45(2):247–262. 41. Pritchett L. Desired fertility and the impact of population policies. Popul Dev Rev. 1994;20:1–55. 42. Guttmacher Institute. Unintended pregnancy rates declined globally from 1990 to 2014. 2018. https://www.guttmacher.org/news-release/2018/unintended-pregnancy -rates-declined-globally-1990-2014. Accessed July 2019. 43.

United Nations Department of Economic and Social Affairs: Population Division. World Family Planning 2017: Highlights. New York, NY: UN; 2017. https://www.un.org/en /development/desa/population/publications/pdf/family/WFP2017_Highlights.pdf.

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44. Engelman R. Six billion in Africa: Africa’s population will soar dangerously unless women are more empowered. Sci Am. 2016;314(2):56–63 https://www.scientificamerican .com/article/africa-s-population-will-soar-dangerously-unless-women-are-more -empowered/. Accessed July 2019. 45. Engelman R, Leahy E. How many children does it take to replace their parents? Variation in replacement fertility as an indicator of child survival and gender status. Population Association of America 2006 Annual Meeting; 2006; Los Angeles, CA. 46. Abu-Ghaida D, Klasen S. The Economic and Human Development Costs of Missing the Millennium Development Goals on Gender Equity. Washington, DC: World Bank; 2004. http://documents.worldbank.org/curated/en/872151468779427043/The-economic -and-human-development-costs-of-missing-the-millennium-development-goal-on -gender-equity. 47. USAID. Family planning and reproductive health. 2019. https://www.usaid.gov/global -health/health-areas/family-planning. Accessed July 2019. 48. Singh S, Remez L, Sedgh G, Kwok L, Onda T. Abortion Worldwide 2017: Uneven Progress and Unequal Access. New York, NY: Guttmacher Institute; 2018. https://www.guttmacher. org/report/abortion-worldwide-2017 49.

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51. Darroch JE, Audam S, Biddlecom A, et al. Adding It Up: Investing in Contraception and Maternal and Newborn Health [Fact sheet]. New York, NY: Guttmacher Institute; 2017. https://www.guttmacher.org/sites/default/files/factsheet/adding-it-up-contraceptionmnh-2017.pdf. 52.

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53. Population Media Center. About us. 2019. https://www.populationmedia.org/about-us/. Accessed July 2019.

4 A Changing Planet Chris Field, David Tilman, Ruth DeFries, David R. Montgomery, Peter Gleick, Howard Frumkin, and Philip Landrigan

We live on a different planet than the one our great-grandparents called home a century ago. It is a warmer planet, a more crowded planet, a planet with fewer species, a planet marked by widespread contamination and by altered biogeochemical cycles. Land and water are not as available, and not of the same quality, as they once were. Most of us once lived in rural areas; now most of us live in cities. These changes have occurred with breathtaking speed, in geological terms—but so gradually in human terms that many of them are nearly invisible to us. In fact, each generation may simply assume that the conditions it encounters are normal.1 But these planetary changes are so far-reaching that they have defined a new geological epoch, the Anthropocene.2 Scientists have cautioned that we risk transgressing planetary limits, with destabilizing consequences.3 We know that planetary changes have extensive impacts on human health and wellbeing—some well documented, others just now coming into focus as our science advances and as our ability to model and forecast over coming decades improves.4 This chapter sets the stage for the remainder of the book by explaining some of the principal ways in which our planet is changing. It begins with one of the best-known trends, climate change. From there it moves to biogeochemical cycles, to changes in land use and cover, to soil loss and degradation, and to water scarcity. Next, it moves on to losses of biodiversity, both extinction of species and reductions in their population sizes. Finally, it considers the issue of widespread contamination of the planet by pollutants.

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Subsequent chapters build on this one, tracing the many ways in which these planetary changes can affect human health—and paths to holistic solutions that protect both people and our planet.

Climate Change Chris Field Climate change is a stark reality of the twenty-first century (Figure 4.1). Since the beginning of the twentieth century, global average temperature has warmed by approximately 1°C. The hottest year in the historical record, 2016, was 1.35°C warmer than the 1850– 1900 average. Human actions, primarily the release of greenhouse gases, are the main cause and probably the sole cause. Recent assessments by the Intergovernmental Panel on Climate Change, a partnership of the world’s governments and scientific community charged with evaluating the evidence, characterize the warming as “unequivocal,” with a greater than 98% probability that human actions account for more than half of the warming since 1950.5 The observed warming is by far the largest change in the last thousand

Figure 4.1 Time series of annual values of global mean temperature anomalies (red and blue bars) in degrees Celsius, and observed carbon dioxide concentrations at Mauna Loa (black line), both from the National Oceanic and Atmospheric Administration. Data are relative to twentieth-century average levels. The latest values exceed 400 parts per million by volume. For temperature, the 2015 value is more than 1°C above preindustrial levels. Source: NOAA, National Centers for Environmental Information, Climate at a Glance: Global Time Series, 2019. Available at https://www.ncdc.noaa.gov/cag/global/time-series

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years, and it is many times larger than could be explained by any natural process or combination of natural processes. Without human actions, Earth would have slightly cooled over the last century. With this warming, we have experienced impacts on every continent and in the oceans. The frequency and intensity of hot days and heatwaves have increased, as has the fraction of rain falling in the heaviest events. A rise of approximately 20 centimeters in global sea level has raised risks of coastal flooding. In response to warming, many plants and animals have shifted to cooler locations, but those unable to move, especially warmwater coral reefs, have suffered substantial dieback. Lengthening of the fire season has increased wildfire risk, notably in the western United States, Australia, and the Mediterranean. Human impacts, from disaster-related mortality to large-scale migrations, almost always have multiple contributing causes, but the fingerprints of a climate component in many are increasingly stark. Recent progress in quantifying the way climate change has altered the odds of individual extreme events makes it clear that human-caused climate change amplified the risk of events as severe as the 2003 European heatwave, the flooding from Superstorm Sandy, and a host of other disasters.6,7 Continued warming increases the risk of impacts that are severe, pervasive, and irreversible. Evidence for the temperature sensitivity of human activities continues to increase. Agriculture, worker productivity, and the potential for economic growth suffer under hot conditions, while risks of violent conflict increase. With greater warming, a larger fraction of hurricanes reach the destructive potential of categories III to V, and more species of plants and animals face increased risk of extinction. Challenges for the most vulnerable people—older adults and the very young, ill, disabled, or poor—become increasingly difficult to manage, as do risks of complex, multifactor impacts such as combined heat, drought, agricultural shortfalls, and migration. With greater warming, we also face an increasing probability of crossing a threshold or tipping point that leads unavoidably to massive long-term changes (Figure 4.2).8,9 One threshold of particular concern is the point at which we become committed to more than 5 meters of sea-level rise, probably over centuries, caused by the collapse of a major ice sheet. Another is the point at which greenhouse gas emissions from the natural biosphere, especially thawing permafrost and burning forests, become so large that they drive further warming, even if human emissions drop to zero. Evidence for the existence of these thresholds is strong, but knowledge of the warming level that triggers each is limited. We have high confidence that risks are lower with less warming and that risks are unacceptably high with warming of 3°C or more, as expected late this century in a world of continued high emissions. Responding to climate change includes two broad approaches: mitigation and adaptation. Mitigation (in public health terms, primary prevention) entails steps to stop climate change, such as reducing greenhouse gas emissions and reducing deforestation.

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Figure 4.2 Potential climate tipping points. Source: Adapted from Rockström J. Climate Tipping Points. Global Challenges, 2019. Available at https://globalchallenges.org/wp-content/uploads/2019/07/Global-Catastrophic-Risks-2017.pdf

Adaptation (in public health terms, disaster preparedness and resilience) entails coping with the changes to which we are committed. These are sometimes referred to as “avoiding the unmanageable” and “managing the unavoidable,” respectively. Adapting to climate change entails a wide range of challenges, but the prospects are best in a world of ambitious mitigation, where warming is limited to less than 2°C. Experience with both planned and unplanned adaptation is increasing rapidly.10 For dealing with extremes, steps such as improved forecasts, early warning systems, and protective features, both manufactured (e.g., seawalls) and natural (e.g., mangrove forests), can limit damage. Good infrastructure for transportation, communications, and public health can make extremes more manageable, and sophisticated insurance and supply chains can help spread risk. Improving buildings and breeding crops for decreased water requirements or increased heat tolerance can make a big difference. In areas with unacceptably high risk of flooding, fire, or other extremes, strategic relocation of industries, communities, or infrastructure may be appropriate, especially if the relocation is part of a larger agenda focused on improving wellbeing. In a world of continued high emissions, many adaptation strategies reach their limits.

11

For example, a heatwave early warning system is of little value if every day is a

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heatwave. Insurance is not a useful tool for sharing risk of flood or fire when those events are so frequent that premiums are unaffordable. Switching from one crop to another is a viable option only if a region has sufficient water for some kind of agriculture. And relocation ceases to be an option once the number of people on the move is so great that it overwhelms all available receiving communities. Stopping climate change—mitigation—will require that net emissions of carbon dioxide and other long-lived greenhouse gases fall to zero and that emissions of methane and other short-lived climate pollutants fall substantially. Limiting warming to 1.5°C requires rapid and dramatic action, with carbon dioxide emissions reaching zero by around 2040. Less ambitious warming targets lengthen the path to zero emissions but with rapidly escalating climate impacts. A smart approach to solving the climate challenge would dramatically accelerate the pace of decarbonization, taking full advantage of the attractive economics and abundant co-benefits of technologies for renewable energy generation, increasing energy efficiency, and protecting and enhancing natural carbon sinks. In the past, the dominant view was that decarbonization, adaptation, and economic development compete for the same resources. Increasingly, it is clear that the best investments advance two or even all three objectives simultaneously. The combination of continued technology innovation and thoughtful, forward-looking policy can dramatically increase the rate of progress on addressing climate change while also sustaining robust economies and vibrant communities.

Biogeochemical Cycles David Tilman The growth of plants, including agricultural crops, is often limited by the availabilities of nitrogen (N) and phosphorus (P).12 Nitrogen is essential for life because amino acids, the building blocks for DNA, proteins, and enzymes, must contain nitrogen. However, throughout the history of evolution of life, available forms of nitrogen were rare. The sand, clay, and rock substrates that formed Earth’s soils contain almost no nitrogen. Although nitrogen in the form of N2 (nitrogen gas) makes up about 80% of Earth’s atmosphere, N2 is so stable chemically that it is not a viable source of biologically usable nitrogen. Only a few types of plants, such as legumes and cyanobacteria, are able to break apart N2, creating the biologically available forms, nitrate and ammonia, which they use to form amino acids and proteins. When nitrogen-fixing plants die, the various forms of organic nitrogen from their tissues build up in soils, and upon their decomposition the nitrogen becomes available to other plants (Figure 4.3). Phosphate (PO4) is the chemical form of phosphorus that plants and animals need. Phosphate is an essential part of the cellular energy-carrying molecule adenosine triphosphate (ATP) and a necessary part of DNA. However, because phosphate is tightly bound

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Figure 4.3 The nitrogen cycle. Human introduction of fixed nitrogen, mostly through fertilizer application, now exceeds all natural sources combined on an annual basis (Tilman D. Forecasting agriculturally driven global environmental change. Science 2001;292(5515):281–284.) Source: Adapted from Pidwirny M. The nitrogen cycle. In: Fundamentals of Physical Geography, 2nd ed. http://www.physicalgeography.net/fundamentals/9s.html

chemically in soil particles, most of it is not available to be taken up by plants, and little phosphorus is dissolved in the groundwater that forms streams, rivers, and lakes. Until recently, these factors made the availabilities of N and P of great importance in determining the structure and functioning of most terrestrial and aquatic ecosystems.13 All this changed over the past century thanks to a revolutionary innovation: the ability to fix nitrogen through an energy-intensive industrial process, the Haber–Bosch process, invented at the turn of the twentieth century. Humans now dominate the fluxes of N and P in ecosystems.14–16 Some of the N comes from combustion of fossil fuels, which changes atmospheric nitrogen gas into nitrogen oxides that are deposited on aquatic and terrestrial ecosystems. Most N and P comes from human manufacturing of N and P fertilizers, which now add as much available N and P to terrestrial and freshwater ecosystems each year as did all natural processes before fertilizer was invented. Why? Rapid growth in the human population globally, and accelerating demand for meat, led to a massive increase in our demand for agricultural crops to feed both our livestock and ourselves. In 1960, 10 million metric tons of available forms of N were used as fertilizer globally.

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However, to meet the food demands of 7 billion people in 2015, the amount of fertilizer nitrogen had increased to 110 million metric tons per year. During this same period, the amount of phosphorus fertilizer applied annually increased from 5 to 18 million metric tons of phosphorus per year.17 These nutrients, which had limited and structured terrestrial and aquatic ecosystems for millions of years, were no longer limiting in many places. These disruptions of nitrogen and phosphorus budgets caused serious harm in many terrestrial and freshwater ecosystems.14–16 Much of the N and P applied as fertilizer is not taken up by crops but instead leaks into other ecosystems, harming them. Some of the agricultural nitrogen consists of ammonia, which can evaporate into the atmosphere and then rain down on natural land ecosystems, damaging some plants and reducing plant diversity.18 Nitrate (NO3–) from N fertilizer quickly dissolves in water and, if not taken up by crops, enters the groundwater, lakes, streams, rivers, and the oceans. Some of the P fertilizer follows a similar path, but most of it is bound to soil particles, which can be carried into lakes, streams, rivers, and the oceans as heavy rains erode soil off farmed fields. Moreover, the N and P that are taken up by crops, and are in the edible parts of crops, are subsequently excreted in the urine and feces of the livestock animals or humans that eat these crops. In richer nations, sewage treatment plants remove much of the P from human waste, but for most of the world, sewage treatment, if it occurs, focuses mainly on disease prevention. Most sewage treatment removes little of the N and P, which enter rivers, lakes, and the oceans. Animal manures are often used as fertilizers and release N and P to the environment in much the same way as other fertilizers. The resultant nutrient pollution from agriculture and fossil fuel combustion, called eutrophication, can dramatically affect both aquatic and terrestrial ecosystems.14–16 Lakes and rivers are a major source of drinking water around the world, and they also support fisheries that provide nutritious food in many nations. When lakes are eutrophic, algae abundance can increase 100-fold or more, with formerly rare and often toxic algal species, replacing the algal species that had formed the base of the aquatic food webs. In severe cases, such as in Lake Erie and Lake Okeechobee in the United States, and in numerous rivers and lakes in China,19 toxins released by algae, often cyanobacteria, make the water unfit for human consumption and can cause massive fish die-offs. Marine coastal regions are also threatened. Explosive growth of algae, often in the form of red tides, can poison seafood and make water unsafe for swimming and, in some cases, for boating. When eutrophic rivers, such as the Mississippi in the United States, enter nearshore marine ecosystems, they stimulate rapid growth of algae, followed by dieoffs. Bacteria decompose the algae, using up almost all of the oxygen in the surrounding water and creating dead zones in which few organisms can survive.20 By 2017, the Gulf of Mexico dead zone, at the outflow of the Mississippi River, had reached an area of nearly 9,000 square miles, or roughly the size of the state of New Jersey (Figure 4.4).

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Figure 4.4 The dead zone in the Gulf of Mexico, at the outflow of the Mississippi River, in 2017. The dead zone is caused by agricultural runoff into the Mississippi River, which leads to eutrophication of coastal waters. Source: Courtesy of N. N. Rabalais (LSU/LUMCON) and R. E. Turner (LSU), from National Oceanic and Atmospheric Administration, National Centers for Coastal Ocean Science

Adding bioavailable nitrogen to the biosphere also affects terrestrial ecosystems, changing their plant species compositions and causing loss of plant diversity.12,18,21 The Netherlands, a highly industrial and intensively agricultural nation, lost most of its heathland ecosystems because of nitrogen eutrophication.22 For thousands of years, a highly diverse mixture of short-statured plants that were efficient at using nitrogen, the limiting nutrient, had dominated the sandy soils of the Netherlands. However, with agricultural and industrial intensification, rates of atmospheric deposition of nitrogen increased about 20-fold from 1950 to 2000. The unprecedentedly high levels of available nitrogen nullified the competitive advantages of the heathland species,23 and Molinia, a previously rare, fast-growing, tall grass that is a poor nitrogen competitor, was able to invade and dominate. Elevated levels of N deposition have similar effects in other terrestrial ecosystems around the world. In some instances, the ecological changes associated with eutrophication alter the composition of species in a system in ways that alter infectious disease exposure. This phenomenon is explored in the field of disease ecology and is discussed in Chapter 6. In addition, the ammonia released from fertilizers and intensive livestock feeding operations poses serious health risks to people living downwind, mainly by forming fine particulate matter. Human impacts on the nitrogen cycle are also a significant contributor to global climate change.24 One of the compounds created by fossil fuel combustion is nitrous oxide, a greenhouse gas about 300 times more potent than carbon dioxide. When nitrogen

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fertilizer is applied to croplands, about 1% of this nitrogen is converted by soil microbes into nitrous oxide. On a global scale, nitrous oxide currently accounts for about 7% of the human-caused annual increase in planetary warming potential. As discussed in the previous chapter, the human population is projected to increase by about 4 billion people by 2100, and per capita buying power is expected to increase greatly with growing prosperity. Global food demand is expected to increase approximately twofold during the coming half century, requiring steep increases in N and P fertilization, if current practices are extended.25 Dramatic improvements in the efficiency of N and P fertilization, as well as more efficient use of land, water, energy, and pesticides, will be necessary if we are to feed the world 50 years from now without having devastating effects on natural systems. Innovations in achieving such efficiencies are explored in more detail in Chapter 5.

Changes in Land Use and Land Cover Ruth DeFries The distribution of land cover types across Earth’s surface reflects a combination of biophysical characteristics such as climate, soil, elevation, and human modifications to grow food and fiber, graze animals, and expand urban areas. Researchers have developed many different land cover classification schemes and routinely map global land cover from Earth-observing satellite data.26,27 Although classification schemes vary, global land cover maps generally depict the spatial distributions of grasslands, deciduous forest, evergreen forest, shrublands, savannas, cropland, urban areas, and other categories. The most extensive land cover on a global scale is currently savanna, followed by tropical evergreen woodlands, deserts, and grasslands and steppe (Figure 4.5). Land use, as distinct from land cover, denotes human management such as fertilizer application, irrigation, use of fire, multiseason cropping, impounding water, and many other activities that people carry out to obtain resources from the land. Changes in land cover and land use substantially influence human health through many pathways: altered habitats for disease vectors, fire emissions that affect air quality, loss of diversity of food supplies with intensive agriculture, vulnerability to extreme climate events from loss of storm-buffering coastal vegetation, and many others. Later chapters in this book explore many of these linkages.

Global Patterns of Land Cover and Land Use Change People have altered ecosystems to grow crops, improve hunting, graze livestock, build cities, and obtain other resources for many millennia. Changes in land cover and land use are the primary modes through which civilization obtains these essential provisioning services.* *Provisioning services are one category of ecosystem services; the others are regulating services, cultural services, and supporting services. Examples of provisioning services include food, fiber, and fuel. Ecosystem services are explored in Chapter 15.

Figure 4.5 Global land area in biomes and expressed as land uses in the years 1700 (bottom) and 2000 (top). Wildlands and seminatural areas are defined, respectively, as nonagricultural land with no population and nonagricultural land with fewer than 100 persons/km2, respectively. Source: Data from Appendix S5 in Ellis EC, Klein Goldewijk K, Siebert S, Lightman D, Ramankutty N. Anthropogenic transformation of the biomes, 1700 to 2000. Global Ecol Biogeography. 2010;19(5):589–606

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The most visible types of land use change involve conversion of one ecosystem type to another, such as conversion of prairie to cropland in North America, forest clearing for pasture in the Amazon, or expansion of urban areas. In 1700, nearly half of global land area was wildland.28 By the year 2000, humans had converted approximately 40% of the planet’s ice-free land surface, primarily to produce food and fodder on rangeland and cropland. An additional 37% of global land is currently seminatural, with substantial human populations embedded within agricultural lands and settlements. Less than a quarter of the land area remains as wildland (see Figure 4.5). On a global scale, savanna, grasslands, shrublands, and temperate and tropical deciduous woodlands have undergone the most extensive conversions. More than three quarters of these biomes have been converted to agriculture (rangeland and cropland) since 1700. Remaining wildlands occur in less arable biomes including tundra, deserts, boreal woodlands, and tropical evergreen woodlands (see Figure 4.5). Other types of land use conversion have affected only small proportions of the land area but have major implications for ecosystems and health. Urban areas cover only a small fraction of the land surface but house more than half of the world’s population. As described in the next section of this chapter, urban land use often expands into prime agricultural land. More importantly, urban areas drive the demand for commercial agricultural products. The highest rates of urban land expansion in the last few decades have occurred in India, China, and Africa, and North America featured the largest absolute change in urban extent.29 Construction of large dams occurs over small areas with both positive and negative impacts. Positive impacts include the provision of reliable sources of water for irrigation, generation of hydroelectric power, and flood control. Negative impacts include altered flow of water and nutrients, with far-reaching ecological consequences for habitats of disease vectors and other species. Although the practice of damming rivers and streams is as old as human civilization, the construction of large structures to dam rivers began in the 1930s. By the end of the twentieth century, more than half the world’s surface water was traversing dams before reaching the ocean. The number of large hydroelectric dams is expected to double by 2030 and to alter the flow of all major rivers on the planet.30 Wetlands, which include mangrove habitats in coastal areas and peatlands, are an additional locus of land use change. Coastal mangroves are highly productive and biodiverse ecosystems. They protect coastal areas against storms, provide spawning grounds essential to healthy fish populations, and support local livelihoods with food, fuel, and construction materials. The rate of loss of mangroves from 1990 to 2000 is estimated to be twice that of terrestrial rainforests, primarily due to expansion of aquaculture in

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the Asia-Pacific region.31 Globally, 20% to 35% of mangrove area has been lost since 1980.32 Peatlands, which accumulate thick stores of partially decayed organic matter in humid areas where plant production exceeds decomposition, store large amounts of carbon. The carbon is released to the atmosphere through burning or decay when drained and converted to agricultural land uses. Peatlands cover only 2% to 3% of the land surface but contain a quarter of the world’s soil carbon.33 Most peatlands are in high northern latitudes and have not been subject to land use conversion. In the tropics, particularly in Southeast Asia, rapid expansion of oil palm, rubber, and other types of agriculture have led to losses of peatlands over the last few decades.

Drivers of Land Use Change The most significant driver of land use change is undoubtedly agriculture (Figure 4.6). Characteristic agricultural transitions generally follow the process of development from pre-agricultural to agrarian to urban-based economies.34 In a transition from pre-agricultural to agrarian economies, small-scale farming results in large areas of grassland and forests cleared for croplands and rangeland. Small-scale farms generally contain high levels

Figure 4.6 Fields of soya beans (left) alongside untouched natural forest in Brazil’s Cerrado ecoregion. Source: Photo by Marizilda Cruppe/Greenpeace

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of agricultural diversity with low inputs of fertilizer, irrigation, and pesticides.35 With industrialization, lower-productivity lands are abandoned as populations concentrate in urban areas. Large-scale agriculture with low agrodiversity and high agricultural inputs expands in lowlands with productive soils as forests regenerate in low-productivity, abandoned areas. Land conversion from undisturbed ecosystems, primarily for the expansion of agriculture, occurred millennia ago in Europe and in the nineteenth century in North America after the Industrial Revolution.36 More recent change in agricultural land use in the industrialized world has been in the form of intensification of agriculture (increased output from the same amount of land) with increased use of agrochemicals, mechanization, and low-diversity cropping systems. A “forest transition,” in which deforestation is followed by a net increase in forest area with industrialization and urbanization, occurred in parts of Europe at various times during the last two centuries and North America during the last century.37,38 More recently, similar transitions have been observed in some countries of the Global South, including China, India, Vietnam, and Costa Rica.39 The primary nexus of land conversion over the last several decades has been in the tropics, as economies there shift from primarily extractive and small-scale agriculture to export-oriented commodity production. With demand for agricultural commodities, both across the planet and increasingly from urban populations in emerging economies, the drivers of deforestation have shifted toward large-scale production of animal feed, animal products, and vegetable oils.34 Global market demands for four commodities—soy, palm oil, beef, and wood products—was responsible for 40% of total tropical deforestation from 2000 to 2011.40 Global demand for commodities such as animal products and vegetable oil is a major driver of tropical deforestation in South America and Southeast Asia. The links between deforestation and global supply chains for high-value commodities have opened opportunities for certification, no-deforestation commitments by multinational companies, and other market-based mechanisms to reduce deforestation.41 Conservation efforts in the past several decades have greatly increased the land area under protected status. By 2018, just under 15% of global land area was under some form of protected status, ranging from fully protected to managed use.42 In addition, 18% of global land area is formally recognized as owned by or designated for Indigenous peoples and local communities.43 The current global distribution of land cover and land use is a mosaic reflecting different economic and biophysical conditions around the world with varying implications for human health. For example, historically the transition from pre-agricultural to agrarian societies coincided with the emergence of epidemic, infectious diseases and loss of

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nutritional diversity.44 In modern times, the transition from small-scale agrarian land uses to urbanized societies with intensive agriculture is accompanied by rising obesity and other noncommunicable diseases.45 Of course, land use is only one aspect of these farreaching changes, but it plays an important role.

Changes in Land Management Changes in land management can be as consequential to human health and ecological processes as conversion from one land use to another. Intentional fire has been used throughout human history and remains a pervasive practice throughout the tropics. Fire is an inexpensive management tool to control pests and clear vegetation and debris. Fire emissions can be transported over large distances and affect air quality and human health downwind.46 For a detailed case study describing efforts to address the health impacts of such biomass fires in Indonesia, see Planetary Health Case Studies: An Anthology of Solutions (https://islandpress.org/books/planetary -health). On a global scale, burned area declined by nearly one quarter between 1998 and 2015, primarily in South American and African savannas and in grasslands across the Asian steppe. Declining trends were associated with high-value agricultural production, suggesting that fires may decline in the future as people increasingly use land to produce valuable commodities.47 Agricultural intensification through multiseason cropping, improved seed varieties, mechanization, and agrochemical inputs has been the primary means through which production has outpaced population growth over the last half century. Production of cereal crops tripled over the past 50 years with only a 30% increase in cultivated land area. Without intensification, an additional 20 to 25 million hectares would have been needed to produce the equivalent amount.48 The resulting decline in real food and feed prices alleviated food shortages but had a number of other consequences: inexpensive feed that underlies increased production of grain-fed poultry, pigs, and red meat; abundance of inexpensive foods that fosters overconsumption; and homogenization of diets with the loss of local varieties.49

Future Land Use The myriad economic and biophysical factors that affect land use decisions make future land use notoriously difficult to predict. However, several trends are likely to affect land use in the coming decades. Expansion of roads, rail, and other infrastructure throughout the Global South will fundamentally change land use patterns.50 With increased access to markets, particularly in urbanizing emerging economies, the demand for agricultural commodities is likely to lead to land use changes in parts of the world distant from consumption. Because tropical forests are the only remaining land area for expansion,

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clearing of tropical forests is likely to continue in the absence of controls. Moreover, as small-scale farmers seek opportunities in growing urban centers and as demand for commodities increases, the predominance of small-scale farming is likely to shift toward more large-scale, intensively produced agricultural systems. Following historical patterns of forest transitions, forest regrowth is likely to occur as less productive agricultural areas are abandoned. These land use transitions will further modify ecosystems and affect diets and lifestyles, exposure to pollutants, and spread of infectious disease, among other health outcomes.

Arable Land and Soil David R. Montgomery The previous section explored the uses of land, and this section extends that discussion by considering the quality of land—in particular, the fertility of soil and the availability of arable land. Fertile land is the foundation for agricultural civilizations, and soil loss and degradation have undermined societies around the world throughout history.51 Soil loss is the displacement of the upper levels of soil, through such processes as erosion by running water and wind, faster than natural soil formation can replace the losses. Soil degradation is a decline in the quality of soil: deterioration of the normally thriving ecosystem of microorganisms, insects, and other species; loss of organic matter; changes in physical structure or chemical composition such as acidification and salinization; and contamination by chemicals. Soil loss and degradation are not just ancient history. In 1995, researchers estimated that one-third of the world’s cropland had been degraded since World War II, with another 0.5% to 1% (about 12 million hectares) lost to food production each year.52 Two decades later, in 2015, a United Nations Food and Agriculture Organization report on the status of the world’s soil resources concluded that soil erosion results in an ongoing annual loss of 0.3% of global crop yields, enough to reduce global harvests 10% by 2050.53 A 2018 United Nations report showed that global land degradation already negatively affects the wellbeing of at least 3.2 billion people—more than a third of humanity.54 As discussed in the previous section of this chapter and shown in Figure 4.5, grazing and croplands cover more than one third of Earth’s land surface. Yet the amount of arable land per capita decreased from 0.45 hectares in 1960, to 0.32 hectares in 1980, and is projected to decline to just 0.22 hectares in 2020.53 The combination of ongoing degradation and loss of agricultural land and a rising human population ensures that this vital statistic will continue to decline in coming decades, making it progressively more challenging to feed the world. Major drivers of arable land degradation include climate change, urban expansion, and agricultural practices that accelerate soil erosion, disrupt soil life, and fuel the

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breakdown of soil organic matter. Agriculture is a primary driver of soil loss and degradation through the effects of irrigation-induced salinization, tillage (plowing), prolonged chemical fertilizer use, and nutrient depletion due to lack of both manuring and the use of crop residues to return nutrients to the soil. Tillage results in soil erosion from leaving bare soil exposed to the action of wind and rain and from degradation of soil organic matter through aeration accelerating microbial breakdown of organic matter. Prolonged use of nitrogen fertilizers can result in soil acidification and depletion of soil organic matter by stimulating microbial decomposition. One analysis confirmed that average erosion rates on conventionally plowed agricultural fields were ten to a hundred times faster than the natural pace of soil production, which itself approximates rates of soil erosion under native vegetation and over geological time. In contrast, no-till agriculture produces erosion rates close to natural soil production rates.55 In regard to soil organic matter, the combination of tillage and intensive chemical fertilizer use that together deplete soil organic matter has, so far, consumed about half of the organic matter in North America’s agricultural soils.56 Urbanization presents a different and growing threat to soils. Expanding urban centers typically consume some of a region’s most fertile land, the very resource that typically drew settlers to an area. Urbanization dramatically degrades agricultural land as pavement and buildings displace fields and orchards. Urban expansion is projected to result in the loss of about 2% of global croplands by 2030, with most of the loss occurring in Africa and Asia, regions where the human population is growing most rapidly. And as urban expansion is expected to be concentrated on above-average cropland, the net loss could amount to 3–4% of global crop production.57 However, intensive production through urban agriculture can offset some of the decline in agricultural land around cities.58 Salinization has been an agricultural problem since Mesopotamian times; early records document a shift from salt-intolerant crops to salt-tolerant ones as repeated evaporation slowly built up the salinity of irrigated fields.51 Globally, about 830 million hectares of land are now affected by increasing soil salinity, and some estimates predict that salinity will reduce the productivity of half of all arable land by 2050.59 Salinization affects far more land in Asia (194 million hectares) and Africa (123 million hectares), and far less in Europe (7 million hectares) and North America (6 million hectares).59 Salinization occurs through both primary and secondary processes: Primary salinization results from the natural capillary rise of saline groundwater in fine-grained soils, and secondary salinization occurs as salts accumulate from the evaporation of infiltrating or standing irrigation water. The effects of salinization vary with the type and concentration of salts and for particular growth stages of different crops. Sea-level rise is particularly concerning for farmlands in low-lying coastal areas, and especially deltaic environments, because of the potential for inundation and for salinization of coastal aquifers.60

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Soil pH changes resulting from long-term applications of nitrogen fertilizers are another growing global problem on conventionally farmed agricultural lands.61 Some soil-dwelling bacteria oxidize ammonia (NH3) to nitrite (NO2–), and others can then oxidize the nitrite to nitrate (NO3–). Each of these steps produces hydrogen ions (H+) that acidify the soil. Soil pH thus gradually decreases with sustained use of nitrogen fertilizer (and especially ammonia), with the biggest decreases having occurred in the world’s grassland soils.61 Aluminum toxicity produced as the pH decreases below 5.5 can restrict plant uptake of critical nutrients such as calcium and magnesium. Increasing acidification of agricultural soils also affects soil life, particularly bacterial communities, and can thereby affect the availability of exchangeable cations (such as Ca2+, Mg2+, and K+) for plants to take up.61 Land degradation has resulted in long-lasting societal effects. For example, history records bountiful Roman harvests in Syria and Libya, areas where such productivity is unimaginable today.51 And although the disaster of the Dust Bowl in the American Midwest in the 1930s (discussed in Chapter 8) placed the problem of soil erosion in stark relief, less well known is how by then substantial damage had already been done to another broad swath of North American soil. The Piedmont, or hill country, on the Atlantic slope of the American Southeast offers a case study of a region where widespread agricultural erosion stripped topsoil from the land (Figure 4.7). Most of the region lost at least 10 centimeters of soil—its topsoil—due to postcolonial soil erosion that peaked in the nineteenth century.62 Today, many farmers in the region plow the subsoil and rely on chemical fertilizers to maintain commercial harvests. This highlights an important type of land degradation that does not show up in global assessments that only account for farmlands taken out of production. So how much of the world’s arable land has been degraded? This simple question is hard to answer. Estimates range from less than 1 billion hectares to more than 6 billion hectares of the global total of 15 billion hectares of land.63 There is no consensus as to the extent of land degradation globally or within individual countries in part because various assessments use different methods and make different assumptions. Global assessments have been based on expert opinion, satellite-derived estimates of net primary productivity (the rate at which plants build biomass), numerical models of biophysical systems, and estimates of the area of historically abandoned cropland.63 Each of these approaches has different limitations, considers varying degrees of degradation, and offers a particular perspective on land degradation. A critically important factor that does not show up in existing global assessments of soil degradation is the loss of the soil life and soil organic matter that drives nutrient cycling in soils. Recent decades have brought a growing recognition of the importance of soil life—of soil ecology—based on the roles of the microbes associated with plant root

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Figure 4.7 Soil erosion in the Piedmont region of the southeastern United States. The image on top, from the 1930s, shows extensive erosion at the site of a previous road. The new road can be seen above and to the right. The image below is Providence Canyon, essentially a huge version of the process shown above. Now a Georgia state park, it is known as one of the state’s seven wonders. The complex of canyons, some as deep as 50 meters, began to form in the early nineteenth century and eventually uncovered geological formations more than 70 million years old. Sources: Photo on bottom: Courtesy of University of South Carolina Library Photo on top: Robbie Honerkamp, Wikimedia Commons, license CC BY-SA 3.0

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systems (a region called the rhizosphere) in influencing nutrient acquisition, chemical signaling, and plant defense, and therefore on crop health.64 This new understanding stresses the importance of soil organic matter as food for microbes that produce metabolites beneficial to the health of soil and crops. Regenerative agricultural practices that build soil health offer a means to reverse soil degradation both rapidly and potentially profitably.65 According to a 2018 UN report, the economic benefits of land restoration average ten times the costs.54 Conversely, the costs of inaction to reverse land degradation are typically three times the cost of addressing the problem.54 Rebuilding fertile soils is also one of the most promising ways to address hunger and malnutrition in Africa.66 For example, recent field trials in Ethiopia show that smallholder farms with higher soil organic matter grew wheat crops with greater zinc and protein content, an important result given the enormous importance of wheat as a staple food crop and the widespread deficiencies of zinc and protein across the human population.67 Farmers have a variety of options for rebuilding the fertility of degraded, nutrientdepleted soils. These options range from choosing crops that help restore nitrogen and organic matter to soils, to conservation practices that minimize soil disturbance, to intensive rotational grazing, and agroforestry and are discussed in more detail in Chapter 5. The scale of global arable land degradation is vast, its causes myriad, and its consequences for global human nutrition concerning. Rebuilding healthy, fertile soils through agricultural practices is one of the critically important challenges for planetary health in the twenty-first century.

Water Scarcity Peter Gleick Fresh water is critical for all human endeavors, from basic needs for drinking, cooking, cleaning, and sanitation to the large-scale production of food and industrial goods and services. Although the total stock of fresh water on the planet is large, it is unevenly distributed in space and time, and it is split into a variety of stocks and flows that are often inaccessible or unusable for humans. Table 4.1 shows the stocks of saltwater and freshwater as a fraction of all global water resources. Total freshwater stocks total approximately 35 million cubic kilometers, which is only 2.5% of all water on Earth, and most of this freshwater is locked up in glaciers, ice caps, and inaccessible groundwater. The limited amount of freshwater, and its uneven distribution, raise the question of water scarcity and constraints on access to water in a world with a growing population and economy. Because the overall amount of water on the planet is extremely

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Table 4.1. Global Water Stocks by Volume (in Thousands of Cubic Kilometers) and as a Percentage of Saltwater and Freshwater Stocks Saltwater Stocks Oceans Saline and brackish groundwater Saltwater lakes Saltwater stocks total

Volume

% of Saltwater Stocks

1,338,000

99%

12,840

1.0%

85

0.01%

1,350,925

100%

Freshwater Stocks

% of Freshwater Stocks

Glaciers and ice caps

24,064

69%

Groundwater

10,530

30%

435

1.2%

35,029

100%

All other freshwater stocks Total freshwater stocks Other Freshwater Stocks Ice, snow, permafrost

% of Other Freshwater Stocks 300

69%

Lakes

91

21%

Soil moisture

17

4%

Swamps and marshes

12

3%

Rivers

2

0.5%

Biological water

1

0.3%

13

3%

436

100%

Atmospheric water Total other freshwater stocks

Source: Shiklomanov I. World fresh water resources. In: Gleick PH, ed. Water in Crisis: A Guide to the World’s Fresh Water Resources. Oxford, UK: Oxford University Press; 1993:13–24.

large, water is “scarce” only in the sense that some users, across all species, cannot access sufficient water to satisfy a specific demand on either a temporary or permanent basis. Thus, scarcity could be due to physical reasons (lack of adequate supply overall, or during extreme events such as droughts), economic reasons (the inability to access adequate water because of poverty or insufficient investment in infrastructure), or institutional reasons (the failure of governments, utilities, or communities to provide adequate water to meet specific demands). (Polluted water represents an additional form of scarcity— scarcity of water of sufficient quality for specific purposes. This is discussed later in this chapter.) Different regions can suffer from each of these forms of scarcity at different

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times. Figure 4.8 shows one estimate of current regional water scarcity, revealing wide geographic differences in water availability. Water scarcity can also be defined in terms of “peak water” limits,68 where more and more regions of the world are confronting constraints on freshwater availability. Water exhibits characteristics of both renewable and nonrenewable resources. Renewable resources are characterized by limits on flows; nonrenewable resources are characterized by limits on stocks. Rainfall and river flows are renewable flows of water, and their use is limited by the size of those flows. Once we consume the entire flows of rivers, we might want more, but we can’t have any more. The total water flows of an increasing number of rivers are fully allocated. Some water resources, such as groundwater systems, are stocks, with extremely slow recharge rates. These resources, sometimes called “fossil aquifers,” act like any classic resource stock such as oil, gas, and coal reserves: They may

Figure 4.8 Estimated water stress globally in 2019. Source: WRI Aqueduct tool available at http://aqueduct.wri.org/, accessed on October 26, 2019, Creative Commons, license CC-BY

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be consumed at rates far faster than they are replenished or recharged. In this case, peak water limits occur when overpumping makes it more technically and economically difficult to extract the next unit of water. Worldwide, a substantial amount of total human use of water—between 20% and 30% of all irrigation water, for example—currently depends on nonrenewable groundwater stocks.69,70 The traditional assumption has always been that water demands (and resource demands generally) will grow as populations and economies expand, leading to projections of rising global water withdrawals (Figure 4.9). Box 4.1 defines key terms associated with water use. The most significant component of projected increases in demand are those associated with agricultural production. Current water demands for agriculture make up about 70% of total human withdrawal of water (and a higher percentage of consumptive use) (Table 4.2). This raises concern that new demands for food production will drive new demands for water for agriculture, with special challenges for regions already experiencing peak water limits and unsustainable use of groundwater. As Figure 4.9 shows, projections of future water demands have been falling over time as actual demand growth has slowed. We now appear to be in a transition away from the conventional assumption of expanding traditional supply to a more integrated effort to identify unconventional water sources and to manage water demands. A key component of this new effort is demand management, including both water use efficiency and water conservation.71 Efficiency improvements are defined here as changes in technologies or policies that permit the same mix of societal benefits (such as growing food, washing clothes, producing industrial goods) while using less water. Efficiency improvements typically involve changes in technology such as drip irrigation systems or high-efficiency

Box 4.1. Water Withdrawals, Consumptive Use, and Nonconsumptive Use Water use can be categorized as consumptive or nonconsumptive. Consumptive use commonly refers to water that is unavailable for reuse in the basin from which it was extracted due to evaporation, incorporation into plant biomass, transfer to another basin, seepage to a saline sink, or contamination. Nonconsumptive use, on the other hand, typically refers to water that is available for reuse within the basin from which it was extracted. Total withdrawals commonly refers to all water used, including both consumptive and nonconsumptive components. Source: Gleick PH, Christian-Smith J, Cooley H. Water-use efficiency and productivity: rethinking the basin approach. Water Int. 2011;36(7):784–798.

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Table 4.2. Global Withdrawals of Water by Sector, 2010, in Cubic Kilometers per Year and as a Percentage of Total Freshwater Withdrawals Municipal

Industrial

Agricultural

km3/year

%

km3/year

%

km3/year

%

464

12

768

19

2,769

69

These figures do not include rainfall used directly in agriculture. Source: FAO, AQUASTAT: FAO Global Information System. http://www.fao.org/nr/water /aquastat/main/index.stm

Figure 4.9 Historical global water withdrawals (black solid line) with projections of future demand made before 1980 (red lines), between 1980 and 1995 (blue lines), between 1995 and 2000 (green lines), and after 2000 (black dotted lines). Over time, with improvements in water efficiency, projections of future demand have been falling. Source: Gleick PH. Water projections and scenarios: thinking about our future. In: The Gulbenkian Thinktank on Water and the Future of Humanity, eds. Water and the Future of Humanity: Revisiting Water Security. New York, NY: Springer; 2014:185–205.

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washing machines and toilets, or efforts to find and eliminate system losses and leaks. Conservation strategies are defined as temporary or permanent changes in behavior that reduce water use, such as taking shorter showers, flushing toilets less often, or voluntary restrictions on outdoor landscape watering. Water utilities or local governments may call for both improvements in efficiency and changes in behavior during droughts or shortterm water shortages. Despite recent successes in some regions in reducing total water use or slowing the rate of increase in water demands, we have already passed the point of unsustainable use of water in many regions. One early assessment suggests that humans are now appropriating more than half of all renewable and accessible freshwater flows.72 More recent studies have tried to assess the use of groundwater and concluded that consuming fossil aquifers for short-term agricultural or economic production is unsustainable.68,70,73 Many rivers no longer reach their deltas because total flows are consumed during part or all of a year, leading to severe ecological collapses and the destruction of fisheries. Avoiding tensions over access to water in water-scarce regions will require identifying alternative options for sustainable water supplies and, especially, improving water use efficiency in the agricultural sector, permitting the production of more crop per drop. Improved efficiency of water use, as well as other agricultural inputs such as agrochemicals, arable land, and energy, are discussed in more depth in Chapter 5 in the discussion of sustainable intensification. This can be accomplished by changing irrigation methods, crop types, and regional planting decisions (especially in the face of changing climatic conditions) and by tackling other aspects of the global food challenge such as dietary choices and waste. Finally, the long-term effort to move to a more sustainable water system involves transitioning to an integrated water strategy. Various approaches have been proposed, including integrated water resource management (IWRM) and the “soft path for water.”74–77 Elements of these approaches include adding alternative supply options such as using treated wastewater and desalination when economically and environmentally appropriate, improving water use efficiency to manage demand, implementing management and institutional policies that protect natural ecosystems, expanding economic pricing and financing tools, and managing water, energy, climate, and food resources together (sometimes called nexus strategies).78,79

Biodiversity Loss David Tilman and Howard Frumkin Biodiversity is the variety of life—the number and complexity of species—either within an ecosystem or on larger spatial scales. It is a complex concept, including functional, genetic, and other dimensions of diversity.80,81 Biodiversity is essential for robust ecosystem

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function; when biodiversity declines, ecosystems degrade,82,83 as do the ecosystem services they provide to humans.81,84 For example, the loss of plant biodiversity causes ecosystems to become less productive, less stable, more vulnerable to invasion by exotic species, and less able to remove CO2 from the atmosphere and store it in soil and living plant biomass.82,85 Biodiversity is declining in ecosystems worldwide. The decline can be seen most clearly in the highly simplified ecosystems of croplands and pastures, in clear-cut temperate and tropical forests, in polluted lakes and rivers, and in overfished oceans and overhunted forests and grasslands.86 Researchers estimate that the population sizes of mammals, birds, reptiles, amphibians, and fishes have declined by roughly 60% since 1970.87 One recent study, across sixty-three protected areas in Germany, indicates that the total biomass of all flying insects declined by 76% over a 27-year period.88 According to the International Union for Conservation of Nature (IUCN) Red List of Endangered Species, as of 2019, population sizes of 40% of amphibian species, 25% of mammalian species, and 14% of bird species have been so greatly reduced that they were threatened with extinction.89 In a Global Assessment of the Intergovernmental Panel on Biodiversity and Ecosystem Services, 145 authors from 50 countries reviewed 15,000 articles over 3 years and, in 2019, warned that roughly 1 million species now face extinction, many within decades.90 The recent rate of species extinctions is perhaps as much as 1,000 times background rates91 and may indicate the start of a mass extinction, the sixth such event in the last half billion years and the most devastating since an asteroid wiped out dinosaurs about 66 million years ago (Figure 4.10).86,92,93 The single greatest cause of extinction risk is the habitat destruction that occurs when new cropland and pasture are created.94,95 Climate change,96 invasive species, and overhunting and overfishing also contribute to the risk of extinction. Unless there is widespread adoption of healthier, low-meat diets and large reductions in food waste, global demand for production of food and feed crops could increase by 70%–100% by 2060, causing ecosystem destruction over more than half a billion hectares of land and massively elevating extinction risks, especially in the tropics.97,98 The 2002 Convention on Biological Diversity, a global agreement, has thus far failed to reduce the rate of species extinctions.99 Biodiversity benefits people in diverse ways,100,101 and biodiversity loss threatens health82 through many pathways, including infectious disease transmission,102,103 impaired immunoregulation (perhaps because exposure to diverse antigens improves immune function),104 and loss of nutrition (discussed in Chapter 5).105,106 Biodiverse natural environments may promote mental health and well-being more than less biodiverse settings, although this point remains controversial.107 As explored in Chapter 6, when habitat fragmentation or other disruptions reduce the diversity of an ecological community, the new composition of species tends to increase human exposure to infectious disease.

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Figure 4.10 Species extinction rates, in extinctions per thousand species per millennium, showing far higher rates in the recent past than in the distant past. “Recent past” refers to extinction rates calculated from known extinctions of species (lower estimate) or known extinctions plus “possibly extinct” species (upper bound). “Distant past” refers to average extinction rates as calculated from the fossil record. “Future” extinctions are model-derived estimates. The levels of certainty around these estimates vary (represented by the height of each bar); they are highest for lower-bound estimates for known extinctions and lowest for estimates based on the fossil record and for modeled extinctions. Source: Millennium Ecosystem Assessment. Ecosystems and Human Well-being: Biodiversity Synthesis. Washington, DC: World Resources Institute; 2005. https://www.millenniumassessment.org /documents/document.354.aspx.pdf

Two specific examples of global biodiversity loss deserve special mention: pollinators and fish. Pollination by insects is an important form of reproduction for more than 35% of the annual global food production by volume.108 At least 87 major food crops and up to 40% of the world’s supply of some micronutrients, such as vitamin A, depend on pollination by insects.109 Pollinators are declining in many parts of the world, probably for a combination of reasons including habitat and forage loss, climate change, pesticide use,

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and parasitic infestation.110 Pollinator loss can reduce the amount of fruits, vegetables, nuts, and seeds in diets, contributing to vitamin A and folate deficiencies. A recent analysis projects that a 50% loss of pollination would cause about 700,000 additional deaths worldwide each year, mostly as a result of increased ischemic heart disease and stroke due to reduced fruit and vegetable consumption.111 Fishery depletion has also emerged as a global problem, with about 90% of fisheries now at or beyond maximum sustainable levels of exploitation.112 Causes include overfishing, ocean acidification, hypoxia, pollution, and nutrient loading. For many human populations, fish are a bedrock dietary source of protein, of micronutrients (often in highly bioavailable form), and of omega-3 fatty acids (mainly from oily fish). Climate change will intensify fishery depletion.113 One study projected that more than 10% of the global population could face micronutrient and fatty acid deficiencies due to fish declines over the coming decades, especially in low- and middle-income countries (LIMCs) near the Equator.114 Above and beyond the tangible value of biodiversity for human health and wellbeing, there is a strong moral case for humans preserving biodiversity. This case rests on the view that all biological entities have intrinsic value, independent of their utility to humans.115 Faith traditions may ground this perspective in reverence for the divine hand seen in the natural world, a framework sometimes called “creation care.”116

Pollution Phil Landrigan Pollution—harmful, unwanted material released to the environment as the consequence of human activity—is an existential threat to planetary health. It is an enormous cause of disease and premature death, responsible for an estimated 9 million deaths annually, 16% of total global mortality.117 Pollution often originates from local sources, but it can spread widely, and, like the other anthropogenic environmental changes discussed in this chapter, it is a global problem that endangers Earth’s support systems and the continuing survival of human civilizations.118 Pollution results from a wide range of human activities. One major source is the combustion of fossil fuels and biomass. A second is the exploitation of naturally occurring but dangerous substances, such as asbestos, lead, and arsenic. A third is the manufacture of dangerous substances that do not occur naturally, such as pesticides and plasticizers. And a fourth is unsafe disposal of human and animal waste, excess fertilizer, and other contaminants. Of course, these simple categories do not capture all the ways in which human activity pollutes the planet. For instance, when tube wells were sunk into groundwater in Bangladesh, naturally occurring arsenic contaminated drinking water over large parts of the country—an inadvertent (and tragic) instance of pollution.119 Pollution arises from multiple sources. These include ancient, traditional sources such as indoor cookstoves and open defecation, which contaminate household air quality and

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drinking water, respectively. Pollution arises also from modern sources such as coal-fired power plants; chemical factories, tanneries, and battery recycling operations; pesticides and herbicides sprayed on fields; mercury released by artisanal and small-scale gold mining; and exhaust from petroleum-powered vehicles. Pollutants contaminate air, water, and soil as well as the places where people live and work and children learn and play. The following paragraphs describe how pollution affects three media: air, water, and soil. They go on to explain the processes through which pollution becomes a planetary health problem.

Air Pollution Air pollution is a complex mix of gases and particles that varies in concentration and composition from place to place and over time. Components include particulate matter (PM), oxides of sulfur and nitrogen (SOx and NOx), ozone, methane and other hydrocarbons, and hydrofluorocarbons (HFCs). As discussed in Chapter 12, fuel combustion is the main source of air pollution. Combustion accounts for 85% of PM globally and for almost all pollution by SOx and NOx. Combustion is also the major source of carbon dioxide (CO2) and short-lived climate pollutants such as black carbon that are the main anthropogenic drivers of global climate change.117 In high-income and many middle-income countries, combustion of fossil fuels—coal, oil, and gas—is the main source of air pollution. Ambient (or outdoor) air pollution predominates. In these countries, pollutants are emitted to the atmosphere from stationary sources such as factories and power plants and from mobile sources—cars, trucks, and buses. In lowand middle-income countries, an additional important source is the burning of biomass— wood, charcoal, straw, and dung—in inefficient cookstoves and open fires. Agricultural and forest burning and obsolete brick kilns also pollute the air. Household and ambient air pollution each affect the other as air flows in and out of buildings. In LMICs, household air can be as contaminated as ambient air and can contribute substantially to ambient air pollution. Household air pollution is declining globally thanks to the wide-scale introduction of cleaner-burning biomass stoves and liquefied petroleum gas stoves. In contrast, ambient air pollution is increasing, especially in rapidly developing LMICs. Key drivers are the uncontrolled growth of cities; rising demands for energy; increases in mining, smelting, and deforestation; the global spread of toxic chemicals; progressively heavier applications of insecticides and herbicides; and the increasing use of petroleum-powered cars, trucks, and buses. More than 90% of the world’s population lives in areas that exceed World Health Organization guidelines for healthy air.120 In the absence of aggressive intervention, the death toll from ambient air pollution is projected to double by 2050.121 Air pollution can travel long distances in the earth’s atmosphere to cross national boundaries, continents, and oceans, altering ecosystems and threatening health far from its source. One analysis found that on days with strong westerly winds (winds blowing

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from China across the Pacific), 12%–24% of sulfate concentrations, 2%–5% of ozone, 4%–6% of carbon monoxide, and up to 11% of black carbon pollution detected in the western United States originated in export-oriented industrial activity in China.122 Similarly, air pollution emitted in Eastern Europe can travel west across national borders and impedes efforts by Western European countries to meet World Health Organization air pollution guidelines.123

Water Pollution Water pollution results from biological contamination of waterways with human and animal wastes and also from contamination of rivers, lakes, and oceans by industrial chemicals, pharmaceutical wastes, plastics, heavy metals, and pesticides. Some of the world’s most heavily polluted water is found in rapidly urbanizing and industrializing LMICs, where local surface waters and groundwater are loaded with both biological and chemical contaminants and no alternative water sources exist. As discussed earlier in this chapter, reduction in the global supply of pure, drinkable water is a major threat to planetary health and global security.124 Water pollution may seem to be a local phenomenon, but it has global dimensions. For example, the world’s oceans and many lakes and rivers are contaminated by mercury. A substantial proportion of this mercury comes from atmospheric deposition of mercury released by burning coal, sometimes in places far removed from the affected waterways.125–127 Similarly, global plastic production now exceeds 300 million metric tons per year, or about 40 kilograms for each man, woman, and child on Earth (Figure 4.11).128 More than half of this plastic is discarded,129 and much of it reaches the oceans, where it is distributed globally.130 Plastics have been found in ecosystems as remote as deep ocean trenches, distant islands, and the far reaches of the Arctic.131,132 Plastics are found also in an estimated 90% of seabirds133 and in large parts of the human food supply, from seafood134 to table salt,135 from bottled water136 to beer.137 Although the health impacts of this pervasive contamination are not fully understood,138 a particular concern is that about 7% of plastics, on average, consists of chemical additives such as plasticizers and flame retardants,129 and plastics also efficiently adsorb other organic chemicals.139 Many of these chemicals are biologically active and can threaten human and ecosystem health.

Soil Pollution Soil pollution results from the disposal of hazardous materials on the land and beneath the surface of the earth. Major sources are active and abandoned factories, mines, smelters, and military bases and their associated hazardous waste sites. Discarded electronic components (e-waste) contribute further to soil pollution and are concentrated at e-waste recycling centers in LMICs. These point sources have created a global archipelago of

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Figure 4.11 Cumulative plastic production since World War II. Cumulative production calculated as the sum of annual global polymer resin, synthetic fiber, and plastic additive production. Most of this plastic still exists. Source: Our World in Data (https://ourworldindata.org/plastic-pollution), Creative Commons, license CC BY

hotspots contaminated by toxic chemicals, radionuclides, and heavy metals.140 Pesticide applications contribute additionally to soil pollution.141 Toxic materials in the soil of farmland and grasslands can be taken up by plants and ingested by humans and animals. Volatile toxic materials in soil, such as polychlorinated biphenyls, can vaporize into the atmosphere and travel long distances to result in pollution in distant areas. Particulate pollutants in soil, such as lead dust, can be lifted on the wind and carried long distances. Toxic chemicals in hazardous waste sites can leach into surface water and groundwater to contaminate drinking water supplies and result in human exposure and ecosystem damage.

Chemical Pollutants as a Planetary Problem The modern chemical manufacturing industry originated in Europe during the Industrial Revolution in the late 1700s and early 1800s. Many products developed during those years remain foundational to the modern industries: sulfuric acid (England, 1736), bleaching powder (calcium hypochlorite; Scotland, 1799), and “mauveine,” the first commercial synthetic dye (England, the 1850s). In 1859, large-scale oil production began at the Drake

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well in Titusville, Pennsylvania, providing virtually unlimited supplies of petroleum, currently the most important chemical feedstock. Chemical production has increased exponentially since the 1950s. More than 140,000 new chemicals and pesticides have been manufactured and introduced into commercial products, including many that never before existed on Earth. Chemicals have become ubiquitous in modern society and are found today in millions of consumer products, including soaps, shampoos, children’s clothing, toys, car seats, herbicides, insecticides, blankets, and baby bottles. The majority of these manufactured chemicals have never been tested for safety or potential toxicity.117 Global chemical manufacture continues to grow at an annual rate of 3.5%, a rate that, if unabated, will result in doubling of chemical production in 25–30 years. Today, more than two thirds of chemical manufacturing takes place in LMICs. This has important implications for planetary health because in many resource-poor countries environmental protections are scant and public health infrastructure weak. Uncontrolled releases of toxic chemicals and unregulated exposures are the too frequent consequences. Several mechanisms are responsible for the dissemination and continuing presence of toxic chemical pollutants in ecosystems worldwide—and for the potential of these chemicals to affect human and ecosystem health.142 These include the rapidly increasing scale and complexity of chemical production, persistence of certain chemical pollutants in environmental media such as water and soil, bioconcentration and biomagnification in food webs, long-range transport, and concurrent Earth system changes such as climate change. These mechanisms, and the broader implications of global contamination of nearly every ecosystem with a burgeoning array of chemical pollutants are explored in greater depth in Chapter 14.

Authors Chris Field, PhD is the Perry L. McCarty Director of the Stanford Woods Institute for the Environment and Melvin and Joan Lane Professor for Interdisciplinary Environmental Studies. In addition to his research on climate change impacts and solutions, Field was the founding director of the Carnegie Institution’s Department of Global Ecology (2002– 2016) and co-chair of Working Group II of the IPCC (2008–2015). David Tilman, PhD, Regents Professor in Ecology at the University of Minnesota, is an experimental and theoretical ecologist whose work has shown why loss of biodiversity harms ecosystem stability, productivity, carbon storage, and susceptibility to invasion. He is a member of the National Academy of Science and a foreign member of the United Kingdom’s Royal Society, and he received the International Prize for Biology, the Heineken Prize, the Balzan Prize, and the BBVA Frontiers of Knowledge Award.

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Ruth DeFries, PhD is the Denning University Professor of Sustainable Development at Columbia University. She applies satellite data and field work to study land use change in the tropics and its impacts on climate, biodiversity, and other ecosystem services. She is an elected member of the U.S. National Academy of Sciences and a MacArthur fellow. David R. Montgomery, PhD is professor of geomorphology at the University of Washington and a MacArthur Fellow. He studies the evolution of topography and the interaction of geological and ecological systems, including human societies. His published work includes more than 200 papers in the scientific literature and five popular-audience books, most recently Growing a Revolution: Bringing Our Soil Back to Life. Peter H. Gleick, PhD is co-founder and president emeritus of the Pacific Institute. He is a hydroclimatologist addressing water, energy, climate, and security issues and is a MacArthur Fellow, a fellow of the American Association for the Advancement of Sciences, an elected member of the U.S. National Academy of Sciences, and winner of the Carl Sagan Prize for the Popularization of Science. Howard Frumkin, MD, DrPH is professor emeritus of environmental and occupational health sciences, and former dean, at the University of Washington School of Public Health. Philip J. Landrigan, MD, MSc is a pediatrician and epidemiologist. He is professor of biology and director of the Program in Global Public Health and the Common Good at Boston College. He is a member of the U.S. National Academy of Medicine. For four decades, Dr. Landrigan has been a leader in environmental and occupational health. His early studies of lead poisoning demonstrated that lead is toxic to children even at very low levels and contributed to the U.S. government’s decision to remove lead from paint and gasoline. From 2015 to 2017, Dr. Landrigan co-chaired the Lancet Commission on Pollution & Health, whose report found that pollution causes 9 million deaths annually and is an existential threat to planetary health.

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121. Lelieveld J, Evans JS, Fnais M, Giannadaki D, Pozzer A. The contribution of outdoor air pollution sources to premature mortality on a global scale. Nature. 2015;525(7569):367–371. 122. Lin J, Pan D, Davis SJ, et al. China’s international trade and air pollution in the United States. Proc Natl Acad Sci U S A. 2014;111(5):1736–1741. 123. Zhang Q, Jiang X, Tong D, et al. Transboundary health impacts of transported global air pollution and international trade. Nature. 2017;543(7647):705–709. 124. Mekonnen MM, Hoekstra AY. Four billion people facing severe water scarcity. Sci Adv. 2016;2(2):e1500323. 125. Obrist D, Kirk JL, Zhang L, Sunderland EM, Jiskra M, Selin NE. A review of global environmental mercury processes in response to human and natural perturbations: changes of emissions, climate, and land use. Ambio. 2018;47(2):116–140. 126. Streets DG, Horowitz HM, Jacob DJ, et al. Total mercury released to the environment by human activities. Environ Sci Technol. 2017;51(11):5969–5977. 127. Streets DG, Lu Z, Levin L, Ter Schure AFH, Sunderland EM. Historical releases of mercury to air, land, and water from coal combustion. Sci Total Environ. 2018;615:131–140. 128. Thompson RC, Moore CJ, vom Saal FS, Swan SH. Plastics, the environment and human health: current consensus and future trends. Philos Trans R Soc B Biol Sci. 2009;364(1526):2153–2166. 129. Geyer R, Jambeck JR, Law KL. Production, use, and fate of all plastics ever made. Sci Adv. 2017;3(7). 130. Jambeck JR, Geyer R, Wilcox C, et al. Plastic waste inputs from land into the ocean. Science. 2015;347(6223):768–771. 131. UNEP. UNEP Frontiers 2016 Report: Emerging Issues of Environmental Concern. United Nations Environment Programme. Nairobi, Kenya: United Nations Environment Programme; 2016. 132. Chiba S, Saito H, Fletcher R, et al. Human footprint in the abyss: 30 year records of deep-sea plastic debris. Mar Policy. 2018;96:204–212. 133. Wilcox C, Van Sebille E, Hardesty BD. Threat of plastic pollution to seabirds is global, pervasive, and increasing. Proc Natl Acad Sci. 2015;112(38):11899–11904. 134. Lusher A, Hollman P, Mendoza-Hill J. Microplastics in Fisheries and Aquaculture: Status of Knowledge on Their Occurrence and Implications for Aquatic Organisms and Food Safety. Rome, Italy: FAO; 2017. 135. Yang D, Shi H, Li L, Li J, Jabeen K, Kolandhasamy P. Microplastic pollution in table salts from China. Environ Sci Technol. 2015;49(22):13622–13627. 136. Schymanski D, Goldbeck C, Humpf H-U, Fürst P. Analysis of microplastics in water by micro-Raman spectroscopy: release of plastic particles from different packaging into mineral water. Water Res. 2018;129:154–162. 137. Liebezeit G, Liebezeit E. Synthetic particles as contaminants in German beers. Food Addit Contam A. 2014;31(9):1574–1578. 138. SAPEA. A Scientific Perspective on Micro-Plastics in Nature and Society. Berlin, Germany: SAPEA; 2019. https://www.sapea.info/topics/microplastics 139. Rochman CM, Hoh E, Hentschel BT, Kaye S. Long-term field measurement of sorption of organic contaminants to five types of plastic pellets: implications for plastic marine debris. Environ Sci Technol. 2013;47(3):1646–1654.

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140. Ericson B, Caravanos J, Chatham-Stephens K, Landrigan P, Fuller R. Approaches to systematic assessment of environmental exposures posed at hazardous waste sites in the developing world: the Toxic Sites Identification Program. Environ Monit Assess. 2013;185(2):1755–1766. 141. Sun J, Pan L, Tsang DCW, Zhan Y, Zhu L, Li X. Organic contamination and remediation in the agricultural soils of China: a critical review. Sci Total Environ. 2018;615:724–740. 142. Bernhardt ES, Rosi EJ, Gessner MO. Synthetic chemicals as agents of global change. Front Ecol Environ. 2017;15(2):84–90.

Part 2 The Health of Populations

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5 Food and Nutrition on a Rapidly Changing Planet Samuel Myers

Looking down on humanity with a long view over the past several thousand years, an extraterrestrial observer might notice a fascinating but concerning nexus of intersecting trend lines at the beginning of the twenty-first century. She would see the long flat line of human population growth over the first several thousand years of human civilization, with a gentle upward rise starting in the 1700s and then abrupt steepening into nearly exponential growth in the 1900s and through the present day. Despite dire warnings from Thomas Malthus in 1798 and many who followed, she would see total and per capita global food production expand rapidly in the 1900s to keep up with demand—one of the greatest public health achievements in human history. She would see related declines in the proportion of the global population suffering from hunger and micronutrient deficiencies and, in the second half of the twentieth century, steep reductions in child mortality and striking increases in global life expectancy. But she would see a different set of trend lines as well, tracing the ecological costs of these achievements: forests cut down to expand agricultural lands, rivers dammed and water appropriated to irrigate crops, fisheries exploited beyond their capacities, atmospheric carbon dioxide rising, proliferation of synthetic fertilizers and changes in global nitrogen and phosphorus cycles, and species driven extinct. Perhaps most striking to our observer would be the extraordinary pace of all of these changes, orders of magnitude faster than any changes she had witnessed in the history of human civilization, and accelerating into the present.

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If she were paying close attention, she might also notice that despite paying these costs, the human population was far from optimally nourished, with nearly a billion people going hungry while unhealthy diets were fueling a growing pandemic of obesity and metabolic diseases such as diabetes, high blood pressure, heart disease, and stroke. Following these trends from a distance, our observer could conclude only one thing: They cannot continue. This is a world that, on its current trajectory, will run out of land and water, fish and forests, and most of the species that make up its biological diversity in a quest to feed humanity. A different path is needed. This chapter starts by outlining the current state of human nutrition globally and projected trends for future food needs. It explores the bidirectional relationship between food production and global environmental change: the outsized impact of global food production on Earth’s natural systems as well as the threats posed to the global food supply by accelerating changes in nearly all the biophysical conditions that underpin our production of food. It investigates what those trends might mean for global nutrition and who is likely to be most vulnerable. Finally, it moves into the rich terrain of solutions, attempting to answer the central question: How can we provide nutritious diets to 10 to 12 billion people without destroying the biosphere?

Nutrition Despite our enormous successes in increasing global food availability and, over the past several decades, reducing the percentage of the global population suffering from undernutrition, the global burden of malnutrition in all its forms remains staggering (Box 5.1). Roughly 2 billion people are deficient in micronutrients including iron, zinc, and vitamin A; 151 million children under the age of 5 are too short for their age; more than 50 million children under the age of 5 are dangerously thin for their height; and 821 million people don’t get enough food to eat.1 As of 2019, these numbers were rising sequentially each of the previous three years. Undernutrition is associated with approximately 3 million child deaths each year, or almost half of the global total.2 Although progress has been made over the past several decades in reducing hunger globally, that progress has left some regions out and has been accompanied by an enormous burden of disease associated with obesity and metabolic disease related to a broad dietary transition sweeping much of the world.3 As populations become wealthier and more urbanized, they have been transitioning to diets richer in animal-source foods, sugar, refined grains and other processed foods, and saturated fats. This dietary shift, coupled with more sedentary lifestyles, is helping to drive accelerating rates of obesity, diabetes, high blood pressure, heart disease, stroke, and some cancers, conditions that, collectively, are responsible for an enormous share of the global burden of disease.4 A key point in thinking about the future of food systems is that, in addition to worrying about ensuring that humanity has enough food to eat, we also need to ensure that we have the right kind of foods to eat.

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Box 5.1. Malnutrition in All Its Forms Samuel Myers Malnutrition is a term that includes several discrete conditions. For most of human history, the dominant nutritional challenge was providing adequate caloric (energy) intake for the global population, and insufficient caloric intake (also called undernutrition) was the dominant cause of the global burden of disease. A second form of undernutrition is insufficient intake of particular micronutrients, such as iron, zinc, vitamin A, or iodine. These conditions are also called micronutrient deficiencies and are still pervasive, affecting billions of people around the world. The impacts of such deficiencies depend on the nutrient but collectively lead to large burdens from infectious disease, reduced work capacity, reduced cognitive function, increased maternal mortality, stunting, and all-cause mortality. A third form of malnutrition, overweight and obesity, has been rising steeply around the world as undernutrition has declined. Overweight and obesity are a significant factor in the growing global pandemic of metabolic disorders including diabetes, hypertension, and dyslipidemia and also increase the risk of heart disease, stroke, and certain cancers. Overweight and obesity result from excess caloric intake and are driven by numerous factors including the adoption of more sedentary lifestyles (and, therefore, reduced caloric needs), economic growth that allows greater access to food, adoption of diets richer in processed foods, added sugars and fats, and a food system designed to encourage overconsumption.a Populations around the world are increasingly suffering from a “double burden” of malnutrition including both nutrient deficiencies and obesity from excess calories.b This development underscores that the global nutritional challenge is not so much to provide adequate calories (although certainly some people are calorically deprived) but to provide nutritious diets for all. Indeed, recent analyses have highlighted that the largest burdens of disease from suboptimal diets globally are caused by excessive intake of sodium and insufficient intake of whole grains, fruits, nuts and seeds, and vegetables.c References a. Swinburn BA, Sacks G, Hall KD, et al. The global obesity pandemic: shaped by global drivers and local environments. Lancet. 2011;378(9793):804–814. b. Abarca-Gómez L, Abdeen ZA, Hamid ZA, et al. Worldwide trends in body-mass index, underweight, overweight, and obesity from 1975 to 2016: a pooled analysis of 2416 population-based measurement studies in 128.9 million children, adolescents, and adults. Lancet. 2017;390(10113):2627–2642. c. Afshin A, Sur PJ, Fay KA, et al. Health effects of dietary risks in 195 countries, 1990– 2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet. 2019;393(10184):1958–1972.

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In the future, the triad of rapid population growth, economic growth that allows people to consume more calories, and a continuing transition toward Western-style diets richer in animal-source foods is expected to increase global food demand at the historically steep pace that began in the 1950s (Figure 5.1). But unlike the 1950s, we are facing constraints in our capacity to appropriate new land, new water, or new fisheries to meet these rising demands. Added to this challenge is the fact that human activity is rapidly changing the environmental conditions that underpin global food production.5

Impacts of Food Production on Natural Systems Although the focus of this chapter is the challenge of providing nutritious diets to a growing population in the face of rapidly changing natural systems, the relationship between food production and global environmental change runs in both directions. The global food production system contributes to each dimension of anthropogenic environmental change discussed in Chapter 4. About one quarter of greenhouse gas emissions come from agriculture.6 Agriculture contributes to other forms of air, water, and land pollution through industrialscale use of agrochemicals including fertilizers and pesticides that alter nutrient cycles, contaminate groundwater, contribute to smog, and can cause direct toxicity.7 Food systems are the dominant sector altering the global nitrogen and phosphorus cycles: Synthetic fertilizers now add more fixed nitrogen to the biosphere than all natural systems combined.8 Conversion of land for agriculture and animal husbandry has led to large-scale habitat loss and fragmentation and is a primary driver of biodiversity loss, land degradation, and water scarcity. None of this should be terribly surprising given the sheer scale of today’s global food production system. In order to feed ourselves, we appropriate roughly 40% of the icefree land surface for croplands and pasture9 and about half the accessible fresh water, primarily to irrigate our crops.10 We are fishing 90% of globally monitored fisheries at, or well beyond, maximum sustainable limits, and wild-harvested fish catch has declined by roughly 1% per year since 1996 as a result.11 In the process we have cut down 7 to 11 million square kilometers of the world’s tropical and temperate forests9 and dammed more than 60% of its rivers.12 In recognition of this immense scale of global food production and its enormous impact on our planet’s natural systems, there is growing consensus that we need to “freeze the footprint” of food production (or, ideally, reduce its footprint).

Impacts of Changing Natural Systems on Food Production and Nutrition As mentioned earlier, not only is food production transforming the global environment, but changing environmental conditions are increasingly limiting our ability to produce nutritious food. Think about what it takes to produce food: arable land, fresh water, the

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Figure 5.1 Historical and projected global dietary energy supply. Historical data are calculated by multiplying the per capita caloric supplies from 1950 to 2011 reported in the FAO food balance sheets by global population estimates from the United Nations Population Division. Historical estimates before 1950 are constructed by multiplying the earliest population-weighted global average of per capita caloric supply from 1947 to 1948 (~2,150 kcal per person per day) by world population in 1800, 1850, and 1900. Future projections of daily caloric supply are estimated by multiplying projected global per capita supplies from 2015 to 2050 by median population projections from the UN. Sources: Per capita caloric supplies: Data adapted from Food and Agriculture Organization. Food supply (kcal/capita/day). Rome, Italy: FAO; 2016. Global population estimates: Data from: http://faostat3.fao.org/download/FB/CC/E and U.N. Department of Economic and Social Affairs, Population Division. Probabilistic population projections based on the world population prospects: the 2015 revision, key findings and advance tables. Working Paper ESA/P/WP.241, New York, NY: United Nations; 2015. Future global daily estimates of per capita caloric supplies: Data from Alexandratos N. World food and agriculture to 2030/2050 revisited. Highlights and views four years later. In: Conforti P, ed. Looking Ahead in World Food and Agriculture: Perspectives to 2050. Rome, Italy: FAO; 2011:11–56.

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presence or absence of biological relationships with pollinators, pests and pathogens, healthy fisheries, the absence of pollution, and stable climatic conditions. It is startling to recognize that human activities are transforming each of these conditions, and many are changing at the fastest rates our species has known. How will these rapid changes affect the quality and quantity of food we can produce, and what will these changes mean for the nutrition and health of humanity?

Soil As discussed in Chapter 4, a combination of drivers has degraded about a third of the world’s cropland, with about 12 million additional hectares—an area the size of Pennsylvania or Malawi—lost to food production each year.13 These drivers include pollution, erosion, salinization, desertification, loss of soil organic matter, soil nutrient losses, and land conversion (into urban areas, roads, and other uses). In China, about 20% of arable land is considered too polluted to be safe for agriculture.14 Globally, soil erosion alone is expected to reduce global harvests by 10% by 2050.15 In much of sub-Saharan Africa, soil nutrient depletion has been reducing the fertility of soils and, consequently, crop yields. Across thirty-seven African countries the average annual nutrient depletion rate has been 22 kilograms of nitrogen (N), 2.5 kilograms of phosphorus (P), and 15 kilograms of potassium (K) per hectare of cultivated land over the last 30 years because of inadequate replenishment with manure or fertilizers.16 On a more positive note, grain production in sub-Saharan Africa has started to improve in the twenty-first century, after nearly 40 years without growth, in part because of soil remediation with fertilizers (Figure 5.2). Loss of soil organic matter is also a problem. The recent finding that smallholder farms in Ethiopia with richer soil organic matter produce wheat crops with higher levels of zinc and protein illustrates that land degradation may affect both the quality and quantity of crop yields.17

Water A second headwind is growing water scarcity. While making up only 20% of cropland, irrigated lands are responsible for 40% of total crop production.18 But our capacity to expand irrigated agriculture to increase food production is likely to be curtailed by scarcity. As discussed in Chapter 4, roughly 50% of accessible fresh water is already appropriated for human uses, mostly to irrigate crops, and water scarcity is expected to continue rising in coming decades. Many of the world’s most important food-producing regions are currently pumping water from deep aquifers much faster than it is being replenished. An estimated 300 million Indians and Chinese depend for their food on fossil water that isn’t being replenished and whose use is therefore unsustainable.19 There are no reliable estimates of how much water scarcity may curtail global crop yields into the future, but clearly access to water represents a growing constraint in many regions.

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Figure 5.2 Trends in cereal yields (tons per hectare) by world region, 1961 to 2016. Source: Data from Food and Agriculture Organization (https://data.worldbank.org/indicator /ag.yld.crel.kg), Creative Commons, license CC BY-4.0

Biological Change Changes in biological communities will affect food production and nutrition in a variety of different ways. Most directly, access to wild harvested fish and terrestrial animals is changing rapidly in response to overharvesting, habitat loss, climate change and ocean warming, pollution, and other drivers. Global wild harvested fish catch peaked in 1996 and has been falling by roughly 1% per year since then.11 Based on current dietary patterns, roughly 1 billion people are at risk for deficiencies of iron, zinc, vitamin A, vitamin B12, and DHA omega-3 fatty acids if these trends continue.20 Ocean warming is expected to reduce further the population sizes of fish and to alter their distributions toward the poles and away from the tropics, where the greatest number of people at risk for such deficiencies live.21 Access to terrestrial wildlife (and other wild-harvested foods) can also determine nutritional outcomes for some populations around the world. For example, research in Madagascar reveals that full enforcement of a ban on wildlife hunting would probably increase iron deficiency anemia among children by about 30%.22 As population sizes of harvested species decline, these nutritional resources are rapidly dwindling.

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But biology is more than something we eat. The presence (or absence) of pests, pathogens, and pollinators plays a significant role in determining the yields of agricultural crops (Figure 5.3). Changes in the density, feeding behavior, geographic distribution, and life cycles of these organisms can therefore have important impacts on crop yields and nutritional outcomes. Insects, pathogens, fungi, and weeds reduce crop production by roughly 25%–40%,23 although systematic global data are limited. Fungal infestations alone reduce global dietary energy availability by an estimated 8.5% annually.24 Changes in biophysical conditions that alter these relationships therefore have strong bearing on global crop yields. A changing global climate is now altering relationships between pests, pathogens, and plants. Warming temperatures increase winter survival of insect pests while making them hungrier.25 A modeling study suggests that increased population growth and metabolic rates among insect pests would increase yield losses of rice, maize, and wheat by 10%–25% per degree Celsius of warming.26 Changing temperatures also shift the geographic range of crop pests and pathogens. Among 612 species of pests and pathogens, investigators have observed an average poleward shift of 2.7 kilometers per year since 1960.27 Crops often lack defenses against nonnative pests and pathogens that are moving into their range, requiring ongoing breeding and management efforts to face new threats. Spatial mismatches between pests and natural predators can also undermine biological control systems.28 As mentioned in Chapter 4, declines in insect pollinator populations are one area of biodiversity loss that affects food production quite directly. Evaluating data from 200

Figure 5.3 Agricultural pests such as this corn borer are expected to take an increasing toll on crops as a result of global climate change. Source: Photo by Jack Dykinga (USDA)

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countries, investigators found that fruit, vegetable, or seed production from eighty-seven of the leading global food crops depends on animal pollinators. They found that about 35% of global caloric production comes from crops that require animal pollination.29 But calories do not tell the whole story; pollinator-dependent crops contribute a disproportionate share of critical micronutrients in the diet, including vitamin A, folate, calcium, and many others.30 In this context, the fact that pollinator species are in decline around the world is of great concern. Indeed, modeling of dietary patterns across 152 countries suggests that a 50% reduction in pollination could lead to 700,000 excess deaths annually from micronutrient deficiencies and increased mortality from heart disease, strokes, and certain cancers.31 It is likely that we are already experiencing significant health consequences of inadequate pollinator populations. Field work in small and large farms across Africa, Asia, and Latin America revealed that about one quarter of the gap between the highest possible yields and the actual achieved yields was due to inadequate wild pollinators. By experimentally increasing wild pollinator density and richness (number of different species present), the investigators were able to close this yield gap by 24% on average.32 These findings, replicated across many different crop systems and geographic regions, suggest that we are already suffering from a “pollinator gap” that reduces the yields of nutritionally important food crops. One of the themes of planetary health is that multiple, large-scale anthropogenic changes can interact in complex ways to affect conditions that are important for human health. In the case of pollinators, loss of habitat and forage, proliferation of pesticides, and infestation with parasites are acting together to reduce pollinator populations.33 Climate change creates an additional headwind by temporally and geographically disconnecting pollinators from the plants they have evolved to pollinate. As temperatures warm, plants flower earlier, and plant communities migrate toward the poles.34 These changes can result in mismatches between mutualistic plant–pollinator pairs, thereby disrupting interactions and ecosystem functionality. Reduced synchronicity between plant flowering and pollinator emergence may compromise pollinator diets, resulting in decreased pollinator abundance and increased extinctions of both plants and pollinators. A further wrinkle is that rising concentrations of atmospheric CO2 are altering the nutrient profile of a wide variety of plants. This has implications for human nutrition (Box 5.2) but may also affect the health of insects and other animals that depend on plants for their own nutrition. For example, goldenrod pollen has lost one third of its protein since the 1840s in response to rising CO2 concentrations, mostly since the mid-twentieth century.35 The implications for the health of pollinators that consume this pollen (and that of other plants that are probably similarly affected) are an active area of investigation. The enormous complexity of these interacting systems and the near impossibility of accurately predicting their collective impacts on food systems is a core theme of planetary health: We cannot alter most of the natural systems on our planet without encountering uncomfortable surprises along the way.

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Box 5.2. How CO2 Emissions Are Making Our Food Less Healthy Matthew Smith and Samuel Myers Carbon dioxide (CO2) levels are rising globally at a rapid pace, on track to surpass 550 parts per million (ppm) by midcentury. Among the many ways that higher CO2 levels and their climate impacts are predicted to disrupt global food systems, another less visible pathway has recently been uncovered: the direct loss of nutrients from crops grown under higher CO2. Free air carbon dioxide enhancement (FACE) experiments (Figure 5.2.1) allow agronomists to grow identical cultivars of the same crop inside and outside a ring of CO2emitting jets, to test the effects of elevated CO2 on the crops while controlling for soil, weather, and biological conditions. FACE experiments in Australia, Japan, and the United States have been carried out on the major food crops wheat, rice, barley, maize, peas, soybeans, and sorghum. The crops grown under elevated CO2 conditions had 3%–17% lower concentrations of important nutrients (iron, zinc, and protein) than those grown at ambient CO2 levels.a This effect was found to be more pronounced in certain crops (wheat, rice, barley) and weaker in others (millet, sorghum, and pota-

Figure 5.2.1 Soybeans growing in a free air carbon dioxide enrichment (FACE) ring. By growing a crop inside and outside of such rings of carbon dioxide emitting jets, it is possible to study the effect of a prescribed CO2 concentration on growing properties or nutritional content of food crops. The crops grown inside the ring are exposed to identical weather, soil, pest, and other conditions as those outside the ring except for CO2 concentration. In this way, agronomists isolate the impact of rising CO2 on crops in otherwise normal field conditions. Source: Bruce Kimball (USDA), Creative Commons, license CC BY-2.0

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toes). Still, other crops (field peas, soybeans, maize) exhibited a mixed response, losing only some nutrients but not all. A subsequent analysis looking solely at rice confirmed these previous findings for protein, zinc, and iron and also found even larger declines of 13%–30% for many B vitamins (thiamin, riboflavin, pantothenic acid, and folate) as well as, inversely, a 14% increase in vitamin E.b Despite the somewhat modest observed declines in nutrient content, the global health implications of many of these losses could be profound. On average, people around the world receive most of their nutrition from plants, including 63% of total dietary protein, 68% of zinc, and 81% of iron.c Because so much of the world population gets its nutrition from plants, it is likely that large parts of the world would consume less of these nutrients coming from crops in 2050 unless significant measures are taken to counteract CO2-driven leaching. Nutritional deficiencies, particularly for B vitamins, iron, zinc, and protein, can lead to a range of health complications, including congenital nervous system defects, lowered immune functioning, anemia, reduced cognitive development, and low birthweight for newborns. Furthermore, despite recent global declines, iron and zinc deficiencies together were still estimated to account for 5.7% of all life-years lost to death or disability as of 2015.d Protein deficiency is not usually estimated on its own, but it contributes an additional 1.7% of total life-years lost. The continuing and equitable improvement of micronutrient status is therefore crucial to promoting and fostering global health in the future. To identify the potential size of the effect of CO2 levels on future nutritional deficiencies, Smith and Myers looked at national diets compared with nutritional needs, and how the nutrient content of each major food responded to elevated CO2 levels, to estimate the size of the population who would be placed at risk of deficiency under 550 ppm CO2.e We found that, in 2050, the number of people at risk of zinc deficiency globally could increase by 175 million, and the number at risk of protein deficiency globally could increase by 122 million. Iron deficiency could not be predicted in the same way because the link between diet and deficiency is poor. Nevertheless, it was estimated that roughly 1.4 billion women and children under 5—those most vulnerable to the adverse effects of iron deficiency—live in countries at highest risk of increased iron deficiency due to rising CO2 levels. A separate analysis of B vitamins in rice predicted that rising CO2 could push roughly 70 million additional people into thiamine deficiency and 130 million people into folate deficiency by the middle of the twenty-first century.f These increases are in addition to the roughly 2 billion people already suffering one or more of these nutrient deficiencies, whose conditions could become more severe without intervention. The places hardest hit by the increased risk of deficiency would be those with many people already on the cusp of deficiency and most reliant on foods that lose nutrients under higher CO2: India and South Asia, Southeast Asia, China, the Middle East, and

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North Africa. India alone accounts for some of the highest burden under higher CO2 levels with a projected 53 million newly protein deficient and 48 million newly zinc deficient. However, these countries are not necessarily destined to see a growth in nutritional deficiency as CO2 rises. Changes in diets or nutritional status between now and 2050 could act to protect them from or to exacerbate these nutritional impacts, depending on other factors that control the composition of diets: income levels, dietary preferences, and growing access to a wider range of foods. Importantly, the wealthiest populations in the world who are responsible for the greatest per capita CO2 emissions tend to be least vulnerable to these nutritional impacts, whereas the poorest populations with much lower emissions are the most vulnerable, highlighting an important issue of environmental justice. References a. Myers SS, Kloog I, Huybers P, et al. Increasing CO2 threatens human nutrition. Nature. 2014;510(7503):139–142. b. Zhu C, Kobayashi K, Loladze I, et al. Carbon dioxide (CO2) levels this century will alter the protein, micronutrients, and vitamin content of rice grains with potential health consequences for the poorest rice-dependent countries. Sci Adv. 2018;4(5). c. Smith MR, Micha R, Golden CD, Mozaffarian D, Myers SS. Global Expanded Nutrient Supply (GENuS) Model: a new method for estimating the global dietary supply of nutrients. PLoS One. 2016;11(1):e0146976. d. Afshin A, Sur PJ, Fay KA, et al. Health effects of dietary risks in 195 countries, 1990– 2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet. 2019;393(10184):1958–1972. e. Smith MR, Myers SS. Impact of anthropogenic CO2 emissions on global human nutrition. Nat Clim Change. 2018;8(9):834–839. f. Smith MR, Myers SS. Global health implications of nutrient changes in rice under high atmospheric carbon dioxide. GeoHealth. 2019;3(7):190–200.

Changes in the quality of air, water, and soil as a result of pollution are also affecting food production. As discussed in Chapters 4 and 14, pollution is a growing problem in many parts of the world and is responsible both for enormous burdens of disease and for compromises in food quantity and quality. Soil and water pollution reduce food quality through contamination with heavy metals, pesticide residues, and pathogenic microbes. These concerns are heightened in regions where water scarcity is driving irrigation with incompletely treated wastewater.36 In addition methylmercury and persistent chemicals are increasingly distributed through the marine food web, threatening both the food

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supplies of fish and marine mammals and, ultimately, human health.37,38 Air pollution can significantly reduce crop yields. In particular, ground-level ozone—produced when products of fossil fuel combustion combine in sunlight and stagnant air—is a potent plant toxin and has been shown to reduce the yields of several staple food crops.39 Ozone affects different crops differently, but an integrated assessment of all food production found that projected ozone exposure alone, associated with a severe but realistic climate change scenario, could reduce aggregate global crop yields by roughly 3.6% by 2050.40 Climate change is an additional pollution-related threat to global food production. There are several comprehensive evaluations of the net impacts of climate change on global food production and nutritional security, and only a cursory summary is possible here.41,42 Climate change promises to exacerbate some of the dynamics already discussed here. It is expected to accentuate water scarcity by changing precipitation patterns, with wet areas becoming wetter and dry areas becoming drier and with precipitation occurring in more extreme events. In addition, glaciers that have provided dry season flow for some of the world’s most populous regions are shrinking rapidly and are expected to disappear while winter snowpack in mountain regions such as the Rocky Mountains and the Sierra Nevada in the United States is melting earlier in the season, disconnecting peak runoff from the height of the growing season. Ocean warming is expected to change the amount and distribution of fish, making them less accessible to populations in the tropics who are most dependent on them as a source of critical nutrients.21 Rising sea levels and more extreme coastal storms are expected to inundate some low-lying coastal areas and exacerbate the problem of arable land degradation. In addition to these changes, the rising temperatures that are guaranteed under a rapidly changing climate threaten crop yields. As of 2011, researchers estimated that climate trends since 1980 reduced global maize and wheat production by approximately 5% relative to a counterfactual scenario with no climate shift.43 Studies that assess the combined effect of changes in precipitation, rising temperatures, and a small positive effect of elevated CO2 concentrations on plant growth conclude that we are likely to see approximately 25% reductions in maize (corn) and 15% reductions in wheat production in the tropics in a scenario where global temperatures warm by 4°C (7.2°F) by 2100.44 Because these studies don’t include changes in pests, pollinators, soil quality, ground-level ozone, or other factors, they must be considered optimistic projections. Climate change is also associated with more frequent and intense extreme weather events including heatwaves, droughts, tropical storms, floods, and forest fires. At the same time, humanity is becoming increasingly reliant on international food trade to achieve nutritional sufficiency. Historically, regional climate shocks have led to breakdowns in markets and trade, exacerbating the food price spikes associated with regional shortages as large producing countries ban exports in order to stabilize domestic food prices. This

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growing vulnerability to climate shocks is concerning, especially with global food production moving away from the tropics and toward the poles, while most human population growth is expected to occur in the tropics. Finally, there are important impacts not only on the quantity of food that will be produced and available through international markets but also on the quality of food. Recent research shows that rising concentrations of atmospheric CO2 are lowering the nutrient content of staple food crops and putting hundreds of millions of people at risk for nutrient deficiencies (see Box 5.2 for discussion). A recent analysis calculates that the effect of elevated CO2 on crop nutrients, combined with the effect of climate change on crop yields, could lead to 15%–20% reductions in the global availability of the critical nutrients iron, zinc, and protein in the diet when compared with scenarios without these effects.45 Box 5.2 illustrates two important themes of planetary health. The first is that, as human activities transform the biophysical conditions on our planet, there are likely to be consequences for our own wellbeing that are hard to predict and often surprising. A second theme is that of equity. Often the populations of people who are most responsible for driving environmental change are also the best insulated (through wealth and infrastructure) from the human impacts, while the poor and future generations bear a disproportionate burden.

Achieving the Triple Challenge We face a triple challenge: First, we need to provide nutritious diets to a burgeoning population when food demand is growing at the fastest rates in human history and poor nutrition is already responsible for enormous burdens of disease. Second, we must do so in the face of a rapidly changing climate, increasing water scarcity, degraded arable land, declines in fisheries and pollinators, and other biophysical changes. Third, we need to achieve these large increases while freezing or, preferably, reducing the ecological footprint of our food production system so as to preserve what remains of our biosphere. Continuing on our current trajectory is untenable. Happily, there is growing evidence that the fundamental transformation of our global food system needed to meet this triple challenge may be achievable. There will be no single “magic bullet,” but a suite of interventions from policy change to technology, from agroecological approaches to behavior change has the potential to deliver a food system that is radically more efficient in its use of energy, land, water, and agrochemicals while providing more equitable and nutritious diets. These interventions roughly fall into three domains: production, waste, and consumption. Before focusing specifically on changes in how we produce and consume food, it is important to point out that delivering food for all is more tractable if “all” is a smaller number. As discussed in Chapter 3, there are important opportunities to improve the

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health and lives of women and children while reducing rates of population growth by expanding access to family planning for couples who desire it. Roughly 40 million births per year (about half the global total) would be prevented or delayed if we could meet the demand for access to family planning from couples without such access.46 Over time, having fewer, healthier children would reduce food demand and help ease the strain on limited resources. A second critical upstream intervention is mitigating global climate change. As discussed throughout this book and specifically in Chapter 10, climate change creates numerous threats to human health and wellbeing, including the impacts on food production discussed above. Although there is much to be done in creating more resilient agriculture, clearly the most effective intervention is primary prevention: redoubling our efforts to minimize climate change itself. Similarly, reducing the trends toward biodiversity loss, water scarcity, arable land degradation, and global pollution are additional upstream interventions that would simplify producing nutritious diets for all.

Transforming Our Food System: Production, Waste, and Consumption Food Production There is strong consensus that we face an ecological imperative to “freeze the footprint” of global agriculture. The climate and biodiversity costs of converting additional forest or other land cover types to agricultural lands (called extensification) are simply too steep. The alternative is intensification: increasing yields in order to produce more food from the same lands. Conventional approaches to improving yields have relied heavily on the use of agrochemicals—synthetic fertilizers, pesticides, and herbicides—in addition to developing higher-yield crop varieties and appropriating water for irrigation. More recently, recognition that the ecological costs of these practices cannot be sustained over time has given rise to an emphasis on sustainable intensification, which implies not only producing more food on the same acreage but doing so with lower inputs of energy, water, and agrochemicals. Innovation in numerous different areas suggests that sustainable intensification is not only possible but well under way. One exciting area of innovation is precision agriculture. Visit an agricultural field in many parts of the developed world today, and you are likely to see unmanned tractors moving across fields equipped with computers and GPS systems. Fields are leveled with lasers to reduce runoff. Farmers map soil conditions to the square meter and enter them into a tractor’s databanks. The tractors plant seeds, remember precisely where each seed is planted, and provide exactly the amount of water and nutrients needed for each stage of growth and each soil type. More recently, tractors are being equipped with robots that can access libraries of hundreds of thousands of images of crops and weeds in different stages

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of health and growth. Such robots recognize weeds and administer plant-specific doses of herbicide. They can also recognize worrisome signs of infestation or disease in crops and notify the farmer or implement appropriate interventions. These developments promise enormous efficiencies in the use of pesticides, fertilizers, and water for irrigation and are progressing very quickly (Figure 5.4). Numerous other innovations are under way. Drip irrigation systems can cut water use by more than 50% while nearly doubling crop yields. Exciting work is under way to reduce the cost of these systems and power them without reliance on electrification by

Figure 5.4 Precision agriculture often includes “smart” tractors accessing detailed geospatial data on soil geochemistry, past crop yields, crop types, and fertilizer and irrigation requirements and guided by GPS systems. Fields can be leveled by laser to reduce runoff, and tractors can be equipped with robotic arms connected to libraries of hundreds of thousands of images of crops and weeds and capable of destroying weeds while assessing crop health. Such an approach reduces water and agrochemical use while increasing yields and efficiency. Source: Adapted from https://www.gps4us.com/

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using solar power, making them much more accessible in lower-income settings.47 Innovation is taking place in microbiology, with researchers identifying soil microbes that make crops more efficient at mobilizing nutrients from soil or more tolerant to drought. Inoculation of soils or seeds with these microbes can lead to more nutritious and droughttolerant crops.48 New genetic techniques are allowing crop breeders to rapidly identify disease resistance genes in wild-type relatives of important food crops such as wheat, potatoes, and maize. These genes can be rapidly screened and then introduced into domesticated cultivars to confer resistance to common pests and pathogens, with striking impacts on crop yields. Such work also underscores the importance of maintaining the biodiversity from which such genes are identified. Agronomists are breeding tree crops better suited to vertical farming, with characteristics that include much shorter stature, shorter time to maturity, and year-round productivity. Although genetically modified crops remain controversial and must be carefully regulated, it is hard to argue that the powerful techniques of genetic modification and breeding should be categorically removed from the armamentarium of solutions given the scale of the challenges we face. Finally, we are seeing a rapid expansion of new production approaches, particularly for produce and farmed fish. Hydroponics, aeroponics, and vertical farming of produce is allowing high-volume production of many types of fruit and vegetables in buildings that can be located near large population centers or among far northern populations (Figure 5.5). These approaches can increase access to nutritious foods and often involve reduced use of water, land, and agrochemicals compared with traditional farming. Already supplying half of the fish directly consumed by humans, aquaculture is another rapidly growing sector of food production (Figure 5.6). With wild-harvested fishing already exceeding sustainable production levels and fish catch falling as a result,11 any increases in global fish consumption will need to be supplied by farmed fish. Both freshwater and marine aquaculture can play significant roles in providing protein, minerals, vitamins, and fatty acids, central to nutritious diets. Innovations in aquaculture will continue to be important to achieve these impacts while limiting negative environmental consequences. Fish farming is evolving rapidly with production of new vegetable-based fish feeds that have much lower impacts on the marine environment than traditional feeds composed of smaller fish. Mixed aquaculture systems that incorporate multiple trophic levels including seaweed, filter-feeding shellfish such as oysters, and fish can be more productive than single-species systems and reduce pollution of surrounding systems with fish feces.49,50 Combining freshwater aquaculture with agriculture can also create valuable synergies, with fish consuming agricultural waste and producing fertilizer that stimulates higher crop yields. Such systems are particularly prevalent in Asia. In developing aquaculture systems, attention must also be paid to who is reaping the benefits. To date, much of

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Figure 5.5 A vertical farming system. Such systems can produce large amounts of fresh produce in or near urban centers with low land, water, and agrochemical requirements. If the energy to power heat and grow lights comes from renewable sources, such systems hold promise as a component of sustainable intensification. Source: Valcenteu (Wikimedia), Creative Commons, license CC BY-SA 3.0

Figure 5.6 A sustainable freshwater aquaculture system producing tilapia. Source: Courtesy of Regal Springs

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aquaculture production is high-value species that are shipped to wealthy countries with minimal positive impact on the diets of nutritionally vulnerable nations. Ensuring that aquaculture is developed so as to provide local nutritional benefits in poorer countries will be critical.51 In addition to all of these promising pathways of technological innovation, there is enormous potential to draw on agroecological principles in order to increase the efficiency and reduce the environmental impacts of food production. One area that has been gaining attention is more careful focus on what we plant and how we plant it. The use of intercropping, cover crops, crop rotation, and pollinator-friendly practices all provide extensive benefits that have little to do with new technology. Intercropping—planting alternating rows of two different crops—uses less fertilizer while allowing 10%–20% increases in yields compared with the yields obtained when each crop is grown on its own.52 Planting a cover crop, instead of leaving farmland barren in autumn and winter, helps retain nutrients in the soil and adds organic material to the soil when the cover crop is plowed into the soil before spring planting. Crop rotation—alternating one type of crop one year with a second type the next year—offers many benefits if the correct crop combinations are used. For instance, in the United States farmers often rotate between planting corn and soybeans. Soybeans are nitrogen-fixing legumes, and corn needs high levels of nitrogen. The rotation maintains yields but decreases the amount of N fertilizer that is used. Planting hedgerows and boundaries with wildflowers and other plants that provide forage and habitat for wild pollinators supports biodiversity and, by increasing the number of pollinators, can significantly increase crop yields.32 A related issue is the increasing homogeneity of food crops worldwide and the loss of diversity in what people eat.53 More than 5,000 plant species can be grown for human consumption, and at least ten times that many have edible parts—but three quarters of the world’s food supply is based on just twelve crops and five livestock species,54 and four crops—soybeans, wheat, rice, and corn—account for just under half of the planet’s agricultural land.55 Around the world, many local cultivars have given way to commodity crops, but they may be rich in vitamins, micronutrients, antioxidants and medicinal ingredients. Moreover, greater agrodiversity helps build food system resilience. Exciting efforts to increase the production of “forgotten crops,” from allanblackia and baobob to wild loquats and yams, through such institutions as the African Orphan Crops Consortium, hold great promise. In addition to the practices outlined above, other agricultural practices can help regenerate soil fertility while simultaneously producing additional services. These include no-till agriculture, intensive rotational grazing, and agroforestry. No-till agriculture minimizes soil disturbance and maintains soils by dramatically reducing soil loss from erosion. Intensive rotational grazing involves stocking dense herds of livestock with frequent

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movement and long recovery times. Agroforestry practices integrate tree growing into multicropping systems. In many settings, these types of regenerative farming can prove more profitable than conventional practices because of their lower input costs and comparable yields after a multiyear transition period.56,57 They can also provide additional societal benefits including pulling carbon from the atmosphere and putting it back into the soil, greater drought resilience, a lower environmental footprint from reduced use of agrochemicals, and the production of additional food and fuel from agroforestry.56 At times there has been tension in the literature between proponents of technological approaches to innovation (called “wizards”) and those advocating for reliance on traditional agroecological principles (called “prophets”). But such tension is unnecessary because both approaches have important roles to play and some are now advocating a “third path” that incorporates both approaches in the service of sustainable intensification.14 One good example of how these approaches can come together is the way that precision agriculture can provide a boost to no-till agriculture. The challenge of no-till agriculture is that the lack of tillage makes it much harder to control weeds. However, the use of tractors with robots that can recognize and remove weeds makes no-till agriculture a much more economically viable and efficient approach. Taken together, soil conservation and restoration techniques, advances in soil microbiology, technological innovations in agricultural and food production methods, and core principles from agroecology and agroforestry have enormous potential to dramatically reduce the ecological footprint of global food production. Just as innovation will be needed to reduce the ecological footprint of food production, innovation is also needed in the other direction: to offset the impacts of rapidly changing environmental conditions on the quality and quantity of food we can produce. Redoubling efforts to breed crop strains that are more heat and drought and salt tolerant and that show smaller nutrient reductions in response to rising CO2 will be important. Adopting pollinator-friendly practices around the world to increase yields of crops that protect our health and simultaneously protect numerous other species is a priority. Impounding water—by recharging fossil aquifers or creating reservoirs—in areas that will experience more variable water flows or disruption of the timing of those flows from climate change may be necessary. Developing global trade agreements that help cushion the most vulnerable from the types of trade failures that have occurred historically in response to climate shocks could save lives. Governments will need to increase their commitments to structures such as the CGIAR system,58 a global network of agricultural research centers, to develop crop strains and agricultural approaches appropriate to rapidly changing conditions and ensure fast dissemination of that knowledge into practice.

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Food Waste In addition to producing food much more efficiently, another critical step in transforming the food system is dramatic reduction of food waste. Roughly a third of the food produced for human consumption every year is lost or wasted.59 If food waste were a country, it would have the third highest greenhouse gas emissions in the world after China and the United States.60 In addition, enormous amounts of water, land, and agrochemicals are wasted every year to produce food that is never consumed. The causes of food loss and waste differ between countries. In lower-income countries, much of the loss occurs early in the food chain at the postharvest and processing levels, whereas in wealthier countries losses tend to occur at the retail and consumer steps. In both instances, an enormous amount can be done to reduce these losses. Grocery stores across the wealthy world are initiating aggressive campaigns to reduce the amount of food that is thrown out because it is “past its date” by using smarter technologies and partnerships to ensure that food is turned into nutritious meals in a variety of ways. In Europe, for example, the Too Good To Go application connects consumers with thousands of grocers, allowing them to be notified when food is being heavily discounted before being thrown away.61 Consumers receive nutritious foods at a fraction of their normal costs, grocers realize a new source of income, and the environment breathes a sigh of relief. In lower-income countries, innovations in food storage and supply chains have the potential to reduce waste dramatically before foods ever make it to retailers.

Food Demand Although there are enormous efficiencies to be achieved in how we produce food and in reducing food waste, there is strong consensus that we also need to change what we eat. In 2019, the EAT-Lancet Commission on Healthy Diets from Sustainable Food Systems published its report “Food in the Anthropocene.”62 The authors reported that changes in global diets would be necessary in order to keep our global food system within a “safe operating space” in terms of planetary boundaries. They evaluated the impact of dietary choices across multiple dimensions of environmental change including climate change, biodiversity loss, water use, cropland use, and nitrogen and phosphorus applications. The authors concluded that continuing on a business-as-usual trajectory would exceed boundaries in all these domains by 2050. However, a dietary shift away from meat, particularly beef, and toward more legumes, nuts, seeds, fruits, and vegetables would dramatically reduce the ecological footprint of our food system. Because so much cropland is used for producing food for livestock, because livestock are inefficient at turning this food into meat, and because ruminants produce large amounts of greenhouse gases, the production and consumption of meat, particularly beef, lamb, and pork, has a dramatically larger environmental footprint than any other element of the food system (Figure 5.7).

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Figure 5.7 Greenhouse gas emissions associated with common animal- and plant-based foods across the life cycle from production to consumption to waste. The chart shows total life cycle greenhouse gas emissions expressed as kilograms of carbon dioxide equivalents per kilogram of consumed product. Source: Environmental Working Group. Meat Eater’s Guide to Climate Change and Health. 2011. https://www.ewg.org/meateatersguide/a-meat-eaters-guide-to-climate-change-health-what-you -eat-matters/climate-and-environmental-impacts/

It must also be noted that our current industrial system of producing meat is problematic for other reasons. Assembling enormous numbers of animals in concentrated animal feeding operations (CAFOs) under conditions that are inhumane and feeding them large amounts of antibiotics so that they can tolerate unnatural diets and environments has contributed to a global pandemic of antimicrobial resistance,63 significant pollution problems,64 and what many consider unethical cruelty to animals. Shifting from livestock consumption to plant-based diets would provide additional benefits in reducing these harms. Importantly, the dietary shifts proposed by the EAT Commission would simultaneously provide more nutritious diets for the global population with substantial reductions in noncommunicable diseases including heart disease, stroke, diabetes, and cancers. Overall, the commission found that adoption of their reference “planetary health diet” would prevent roughly 11 million deaths per year, or about 20% of total adult annual mortality—a staggering gain in global health.62 The calculus is fairly straightforward in wealthier populations where there is a clear win–win for both health and environment in reducing meat consumption. In poorer populations, the picture is more nuanced. In both populations, reducing consumption of processed foods with added sugars, salt, and saturated fats is an important health priority.

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But in poorer populations with less diverse diets, increasing dietary diversity and nutrient-rich foods is paramount, and animal source foods can represent an important, even critical source of nutrients. In these populations, the environmental footprint of healthier diets rich in fruits, vegetables, nuts, seeds, and legumes is not necessarily more favorable than existing diets of starchy staple foods. An additional concern is that nutritious foods are costlier than less nutritious sources of calories,65 a burden for poor populations. This pricing is an example of a market failure in that the cost of unhealthy diets to society is very large in burden of disease and associated health care costs. In addition to changing dietary practices, new frontiers are opening up in alternative foods with similar taste or improved nutritional profiles but lower environmental impacts than conventional foods. A recent area of innovation is the production of plant-based fake meats that provide the taste and mouthfeel of red meat with lower environmental impacts. As of 2019, meat substitutes Beyond Meat and Impossible Burgers were being sold in more than 68,000 locations, including large fast food chains and groceries with tens of millions of plant-based burgers having been sold.66 Perhaps even more innovative, cell-based meat, dairy, and egg substitutes have begun to emerge. In one technique, yeast is modified to produce an identical protein mix to that found in milk with the addition of plant-based fats and sugars to replace those normally found in animal milk. A similar process is being used to create yeast-based egg whites that are identical to those from a chicken. Some pundits believe the widespread application of this type of protein fermentation to produce proteins of nearly any design with dramatically reduced environmental footprint, lower costs, improved health benefits, and the absence of animal cruelty may drive a precipitous decline in conventional animal husbandry over the coming decades and free up enormous amounts of agricultural land.67,68 Innovation is also occurring in the production of foods with new ingredients that have much smaller environmental footprints, including duckweed, algae, mycoprotein, and even insects and insect meals.14 Several innovative approaches to reducing food waste, encouraging insect or insect meal consumption, and using school lunch programs to teach children about vegetable-based diets are explored in more depth in Planetary Health Case Studies: An Anthology of Solutions (https://islandpress.org/books/planetary -health). Changing dietary patterns is a complex undertaking and will require a mix of education and behavior change, government policy, and corporate responsibility. Meat consumption has decreased (with a shift from red meat toward fish and poultry) in many wealthy countries in recent years.69,70 In the United Kingdom, for example, supermarket survey data in 2018 indicated that one in eight Britons reported being vegetarian or vegan, and another 21% self-identified as flexitarian (defined as a largely vegetable-based diet supplemented occasionally with meat). But changing dietary patterns is complex. People identify what they eat with their family and cultural heritage, with group identity,

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with beliefs about health, environment, and animal welfare, and with other factors.71,72 Price is also important. Governments have an opportunity to address the market failure of higher prices for healthier foods by taxing less nutritious foods or subsidizing more nutritious choices. They will also need to shake off the sort of legislative capture that is allowing strong food industry lobbies around the world—particularly the beef, dairy, sugar, and ultraprocessed food and beverage industries—to stymie national dietary guidelines aimed at improving nutrition and environmental sustainability in all but a handful of countries.3 The private sector has important responsibilities in promoting dietary change as well. Disruptive food companies such as Beyond Meat and Impossible Burger can help ease the way into a dietary transition by making choices that are good for health and the environment as attractive to consumers as possible. Large agrifood businesses could take more responsibility in producing and marketing foods that are better for people and the planet as opposed to externalizing the costs of their products onto society as a whole.

Conclusion Later chapters of this book emphasize other pivotal issues that have played a large role in bringing us to our current planetary health crisis—energy production, urban development, business and economic models, and chemical manufacture—but that also have the potential to play critical roles in delivering us from this crisis into a more hopeful future. The food system is one of those pivotal issues. It has an enormous global ecological footprint and has been underdelivering in providing universally nutritious and healthy diets. By embracing a suite of accessible innovations and policies, we have the opportunity to remake our food system in a way that simultaneously improves global health and preserves what remains of our biosphere. Coming back to our extraterrestrial observer with the long view across millennia, she would see this moment as one of history’s great dramas. Can we disconnect feeding the human population from destroying our biosphere? Can we thread the needle between hunger and malnutrition on one hand and progressive environmental degradation on the other? Like all good drama, it comes down to the decisions we make right now, today. It comes down to the innovations we develop, the research we conduct, the policies we put in place, the investments we make, the diets we choose, and, fundamentally, our collective will to forge a sustainable path forward.

Author Samuel Myers, MD, MPH is principal research scientist at the Harvard T.H. Chan School of Public Health and director of the Planetary Health Alliance.

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6 Planetary Health and Infectious Disease Richard S. Ostfeld and Felicia Keesing

Humans have been battling infectious diseases throughout their history, and many of these battles have been quite successful. Some diseases, such as measles, mumps, rubella, varicella, diphtheria, hepatitis, and pertussis, are preventable with vaccines. Vaccinated people are themselves protected, and even unvaccinated people can avoid exposure if a sufficient fraction of the population has been rendered immune because infected humans are the sole source of transmission. For other diseases, such as the common cold, seasonal influenza, and some types of pneumonia, vaccines are either unavailable or only partially effective. But for these diseases, prevention is still possible, facilitated by personal hygiene and other behavioral changes. From an epidemiological perspective, these are relatively simple disease systems because the pathogens specialize on humans, and transmission can occur only from infectious to susceptible people. Decades of scientific study have revealed key characteristics of the pathogens, including their routes of transmission and virulence, and important characteristics of the human host, including resistance, tolerance, and threshold population densities, which together influence contact rates and infection. These characteristics of the pathogen and host determine which strategies are most likely to be effective in preventing epidemics and have thus guided effective prevention (Box 6.1). Increasingly effective control of these human-specialized infectious diseases in the twentieth and twenty-first centuries has coincided with the emergence and resurgence of many other infectious diseases.1,2 Most of these so-called emerging infectious diseases of

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Box 6.1. Terms and Definitions Infectious diseases are illnesses caused by a pathogen or parasite that can be transmitted from an infected host to a susceptible individual of the same or another species. The terms pathogen and parasite are sometimes used interchangeably, although often the term pathogen is restricted to microscopic organisms such as bacteria, viruses, and some fungi (but also including aberrant, transmissible proteins called prions), whereas parasite refers to multicellular organisms or protists that make their living on or in another organism by extracting resources from that organism. The organism in or on which the parasite or pathogen lives is considered the host. By definition, parasites and pathogens cause harm to their hosts. When parasites and pathogens invade a host and colonize successfully, we consider the host infected. Sometimes the term infested is used to refer to parasites that attach to hosts but remain external. Some parasites and pathogens have a simple life cycle, with one life stage, whereas others have complex life cycles with two or more life stages, each of which can infect a different species of host. Parasites with complex life cycles can use some host species to support immature stages and other species to support their reproductive (or adult) stages. The former are considered intermediate hosts and the latter definitive, or reproductive, hosts. The movement of parasites and pathogens from one host to another is called transmission, and the way that they typically move between hosts is called the transmission mode. When a parasite or pathogen is transmitted between hosts through direct contact or near contact, the transmission mode is called direct transmission. One subcategory of direct transmission is sexual transmission. Sometimes a parasite or pathogen leaves a host but does not immediately infect another, remaining in the environment for some time in a free-living stage. Yet other parasites or pathogens cannot be directly transmitted or occur in free-living forms but instead need a vector for transport from one host to another. Typically, the vectors are arthropods, including mosquitoes, other biting flies, ticks, fleas, or lice. When a parasite or pathogen tends to infect only a single host species, it is considered a specialist, or single-host pathogen, but when it can infect more than one host species, it is called a multihost pathogen. For multihost pathogens, it is often the case that a few host species allow the pathogen to replicate and persist; these are called the reservoir hosts. Typically, reservoir hosts are affected only mildly by the pathogen, and if the infection is long-lasting (chronic), they can disperse or “shed” many pathogens over a long period of time. Reservoir hosts are particularly important in allowing the pathogen to persist and spread in a host population or community. Other hosts might

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be infected by the pathogen but not allow the infection to persist long enough for the pathogen to leave the host. These are called dead-end hosts. Two reasons why infections in dead-end hosts are short-lived are the rapid clearing of the infection by host immune system and rapid host death. When the reservoir for a pathogen that infects humans is a nonhuman vertebrate species, the pathogen and consequent disease are called zoonotic. The ability of a host to support pathogen infections and transmit them to the environment, to vectors, or directly to other hosts is called its reservoir competence, which can often be quantified by the probability or rate of transmission from the host. When the most competent reservoirs for zoonotic pathogens are species that live in or near human dwellings, that is, synanthropic species, risk of transmission can be high. humans are zoonotic, which means that the pathogen replicates within, and is transmitted to, humans from one or more nonhuman vertebrate hosts. Some zoonotic pathogens, as well as some that specialize on humans, are transmitted by arthropod vectors, such as mosquitoes, fleas, and ticks (Table 6.1). For all zoonotic diseases, the pathogen resides in other animals besides humans, and transmission to humans is affected not only by characteristics of the pathogen and its human host but also by changes in environmental conditions that affect the zoonotic host and, for vector-borne diseases, the vectors. Transmission between zoonotic hosts, and between hosts and vectors, is in turn influenced by the ecological communities in which these species occur. The sheer number of species and transmission pathways involved in these emerging diseases adds considerable complexity to these disease systems, challenging our ability to prevent and control disease. Indeed, few of the emerging infectious diseases of the past 50 years are well controlled, and outbreaks remain unpredictable.3 Table 6.1. Categories of Infectious Diseases of Humans A. Vector-borne, pathogen transmitted from nonhuman vertebrate to human (zoonotic)

B. Vector-borne, pathogen transmitted from human to human

C. Non–vector-borne, pathogen transmitted from nonhuman vertebrate to human (zoonotic)

D. Non–vector-borne, pathogen transmitted from human to human

An example of diseases in cell A would be Lyme disease, where the vectors are ticks and the main sources of infection (reservoir hosts) are small mammals. An example of diseases in cell B would be malaria, where the vectors are mosquitoes and humans act as both the reservoir and victim of infection. An example of diseases in cell C would be leptospirosis, in which transmission is from reservoir hosts (rodents) to humans, with no involvement by vectors. An example of diseases in cell D would be pertussis, with only human-to-human transmission not involving vectors. Notably, some diseases, such as AIDS, severe acute respiratory syndrome, and Ebola disease, can fall into both cells C and D, with initial zoonotic transmission followed by human-to-human transmission.

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In many respects, the traditional health sciences are no longer adequate for contending with the increasing number and impacts of emerging infectious diseases. Risk of human exposure may depend more strongly on the population dynamics or behavior of some zoonotic host or cryptic vector than on the hygiene of people or intrinsic properties of the pathogen. And the dynamics of zoonotic hosts and vectors are in turn affected by environmental conditions, some of which are profoundly influenced by humans. Understanding emerging infectious diseases in the context of planetary health requires the exploration of all phases in the stream of drivers, causes, mediating factors, and health effects illustrated in Figure 1.4. Similar to the traditional health sciences, scientific inquiry in the realm of planetary health depends on experimental, modeling, and correlational studies, but with a somewhat different emphasis on each. In the biomedical sciences, experimental studies are the gold standard, for good reason. For example, experimental studies have been instrumental in revealing microbial causes of human disease, and experimental tests of vaccines and drug therapies can rigorously evaluate efficacy. In the realm of planetary health, however, definitive experiments are often less feasible. For instance, to test the hypothesis that global climate change is responsible for increasing the human population at risk of contracting malaria, a rigorous experimental design would be to impose global warming on a replicated set of Earths, with another replicated set of Earths not warmed to serve as the controls. Given the impossibility of this grand experiment, scientists must rely on other methods, including more modest experiments (such as testing how mosquito biting survival or biting rate changes with temperature), combined with models that convert experimental data (including temperature-dependent changes in mosquito demography and behavior) into human risk, and also combined with correlations (e.g., between temperature gradients and incidence rates of malaria). Planetary health asks big questions at big scales, and we should not be surprised that no simple, elegant experiment will adequately answer them. Below we will explore how the major ecological drivers in Figure 1.4 influence human exposure to infectious diseases, as well as some of the factors that mediate how exposure risk is converted to incidence of infectious disease. For each of the ecological drivers, we first describe general principles that relate the driver to key determinants of exposure risk, then we illustrate the principles with specific examples of emerging or reemerging infectious diseases. For each example, we emphasize the types of studies (experiment, model, correlation) used to develop knowledge.

Climate Change Pathogens, vectors, and reservoir hosts all can be affected by weather patterns and overall climate. Typically, combinations of temperature, precipitation, and vapor pressure determine the coarse geographic range limits of these species. Overall averages, seasonal averages, and seasonal or overall ranges can influence whether a species can occur in

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a particular location. Where combinations of climatic conditions permit species occurrences, abundances and activity levels of these species can fluctuate with daily and seasonal changes in weather. For virtually all taxa, species richness is greatest at low latitudes and declines with increasing latitude; pathogens, vectors, and vertebrate hosts are no exception.4 For ectothermic organisms (those that use external sources to regulate body temperature, also called cold-blooded), developmental, physiological, and behavioral rates generally increase with increasing temperature. From these basic correlations between gradients in weather and those in biotic patterns (e.g., number of species), one might expect that pathogens and vectors, which are most diverse in tropical and subtropical regions, might expand to higher latitudes as the climate at higher latitudes warms. Moreover, one might also expect that these taxa, which are ectothermic, would experience more rapid population growth and blood-feeding activity under warmer conditions. Putting this all together, we might expect range expansions to accompany climate change, and these range expansions might be combined with accelerated development and population growth rates of pathogens and vectors, as well as increased contact rates between vectors and hosts. If these things were to occur, they should increase risk of pathogen transmission. These observations are intuitive and seem to support the notion that a warmer world will be a sicker world (Figure 6.1). However, these a priori expectations can be overly simplistic.

Figure 6.1 Reported cases of Lyme disease in the United States, 2001 and 2017. One dot is randomly placed in the county of residence of each case. The maps show the striking geographic spread of cases of Lyme disease in the United States in the early twenty-first century. Northward spread in the Northeastern and Midwestern foci, and inland spread from the East, is consistent with climate warming facilitating tick invasion of areas that were formerly too cold for tick establishment. Other ecological and demographic factors are probably important in contributing to spread. These factors include forest fragmentation, changes in the communities of vertebrate hosts, suburbanization that juxtaposes homes with tick habitat, and more efficient reporting by health agencies. Source: Centers for Disease Control and Prevention, https://www.cdc.gov/lyme/datasurveillance /index.html

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One complicating factor is that species ranges and population dynamics are influenced not only by temperature but also by other abiotic and biotic variables. For instance, areas that become warmer but also drier might not become more suitable for a particular vector species.5 Similarly, under global climate change, poleward expansions of vector populations might be accompanied by contractions at lower latitudes, perhaps leading to a poleward shift with no net change in geographic range. In addition, the relationship between temperature and vector or pathogen population growth might not be linear; populations could increase with temperature up to a threshold but then decline or be extirpated if it becomes too hot. Finally, vector control, habitat alteration, and human infrastructure can prevent range expansions of diseases even when abiotic conditions would permit them in principle. Malaria, caused by parasites in the genus Plasmodium and transmitted by Anopheles mosquitoes, is currently most prevalent in tropical and subtropical areas, and public health professionals are concerned about its potential to invade more temperate areas as the climate warms.5–7 The World Health Organization (WHO) estimates that there are about 212 million cases of malaria in the world annually, with 429,000 resulting in death, primarily in young children.8 Explaining recent changes in the distribution and prevalence of malaria, and predicting future changes, are both fraught with problems that arise when intuitive expectations and complicating factors collide. Malaria occurred at least seasonally in vast portions of the temperate and even boreal zones globally as recently as the nineteenth century, so we know that cooler conditions can be suitable for this disease.7 The present-day absence of malaria from most of the temperate zone is a consequence of the massive conversion of mosquito breeding habitat to agricultural fields, decimation of mosquito populations largely from use of DDT, and widespread use of antimalarial drugs. However, the historical efficacy of these interventions is unlikely to persist. Additionally, large-scale land conversion to remove mosquito breeding habitat seems untenable, DDT and some other environmentally damaging insecticides are restricted or banned in much of the world, and both the mosquitoes and parasites have evolved resistance to the major chemical interventions.9 As a consequence, the question is not whether the climate in much of the north temperate zone is suitable for the reinvasion of malaria but whether it will become more suitable as the climate warms and, if so, how much more suitable. Two general methods have been used to generate predictions about changes in the distribution of malaria with climate change. The first consists of statistical modeling to identify climate or weather correlates of the present-day distribution of malaria. In theory, malaria currently occurs within a geographic “envelope” where climatic conditions are suitable and does not occur outside that envelope, where conditions are assumed to be unsuitable. Using global circulation models, one can then ask where the conditions that are currently suitable for malaria are likely to occur in the future and draw maps

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projecting the future distribution of the disease.10 Unfortunately, this approach assumes that climate, and only climate, determines the present-day distribution of malaria. But this assumption is not valid. Because malaria previously occurred outside the putative present-day climate envelope, any projections of future distributions based solely on climatic correlates will necessarily be overly conservative. It will predict that malaria cannot occur in areas where in fact it really could, based only on climatic limits. When statistical models are based on a set of correlates (in this case, a set of climatic conditions that correlate with present-day malaria) but fail to include other known determinants (in this case, habitat conversion, insecticide, and chemotherapies), they are likely to be of limited use in explaining or predicting patterns. Combinations of experimental and modeling methods can provide a more robust approach for assessing how climate change might affect the future distribution of malaria. Laboratory and field experiments can provide data linking specific weather parameters to specific parasite or vector life history parameters. For example, rates of Plasmodium and Anopheles development increase with increasing temperature over a wide range of ambient conditions. Mosquitoes bite more frequently with increasing temperature, accelerating both vector-to-host and host-to-vector transmission rates. But the mortality rate of adult mosquitoes also increases with increasing temperature, which can curtail opportunities for transmission. As a result of the multiple, interacting effects of warming temperatures on parasite and vector life histories, the net effects of warming on transmission potential are difficult to discern without mathematical models. Such models, which translate temperature-dependent vital and behavioral rates into an aggregate measure of disease risk,11 generally reveal a left-skewed curve (a curve with a long, shallow slope to the left of the mode and a short, steep slope to the right of the mode) in which disease risk rises roughly linearly with temperature until it reaches a peak at the optimal temperature, after which risk drops dramatically (Figure 6.2).5 These models generate an expected change in disease risk for any marginal change in temperature, specific to any baseline temperature. Such model projections can be useful for asking whether a particular locality, with a known baseline temperature, is likely to experience an increase in risk with climate warming. Potentially, locality-specific predictions can be scaled up to regional or even global projections. To account for the complexities inherent in predicting changes in the distribution and intensity of malaria, more sophisticated approaches include experiments incorporating effects of not just average temperatures but also daily temperature variability on transmission risk,12 region-specific modeling studies that incorporate dynamics of human exposure and immunity along altitudinal gradients,13 and global models that ask about separate and interacting effects of climate change and expected growth in per capita gross domestic product (GDP) in affecting the numbers of people at risk.14 Overall, it appears that climate warming will result in geographic shifts in the distribution of malaria,

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Figure 6.2 Entomological inoculation rate (EIR) and vectorial capacity vary with ambient temperatures, initially increasing and then precipitously declining with warmer conditions. Both influence human risk of exposure to vector-borne infectious diseases. In cool and moderate climate regimes, rising temperatures often mean increasing exposure. However, in hot climate regimes, increasing temperatures can exceed the thermal optimum for vectors and lead to steep declines in risk of exposure. Source: Adapted from Alitzer et al. Climate change and infectious diseases: from evidence to a predictive framework. Science. 2013;341(6145):514–519

entailing an unevenly distributed net expansion in the size of the human population at risk.5,14 Expansion will be greatest in the temperate zone and in higher-elevation areas worldwide, with modest contraction from drier, hotter areas at low latitudes. The geographic expansion could be slowed or even stopped in regions that experience substantial increases in per capita GDP, which can prevent increased transmission efficiency from converting into exposures by supporting protective infrastructure, an example of the sort of mediating factor described in Figure 1.4.14 Increasing our ability to understand how climate change is currently affecting the distribution and prevalence of vector-borne diseases such as malaria, and predicting future changes in risk, is an enormously important undertaking. Vector-borne diseases causing huge global health burdens include not only malaria but also dengue fever, yellow fever, schistosomiasis, leishmaniasis, Chagas disease, Lyme disease, Zika fever, and many others. All these diseases share features that make them responsive to a changing climate, although the details of the ways in which the pathogen, vector, and hosts respond to

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climate change are still being pursued. Understanding those details is necessary but not sufficient to predict future patterns; it is also necessary to understand how human behavior, institutions, and infrastructure will affect exposure and how climate change will influence human capacity to adapt. Climate change can affect infectious diseases via other pathways as well, some of which do not involve effects on vectors or zoonotic reservoirs. For example, when climate change displaces human populations or causes waves of emigration, the probability that immunologically naive people will move into areas of high risk of disease exposure may increase. If climate change–induced displacement is severe enough that it leads to formation of refugee camps, diseases such as measles and cholera are more likely to spread. And when climate change reduces the quantity and quality of food and increases rates of malnutrition, immunity to various infectious diseases can decrease, resulting in higher disease-caused morbidity and mortality.

Biodiversity Loss Traditional approaches to human infectious diseases tend to focus on pathogens with simple transmission modes that specialize on humans. But because most infectious diseases of humans are zoonotic, the maintenance and transmission of the pathogen to humans involve other species. Typically, the zoonotic pathogen interacts with multiple nonhuman hosts, each of which can affect the overall abundance and distribution of the pathogen and hence the risk of human exposure. Disease biologists tend to focus on the smallest set of primary reservoirs of infection—species that are responsible for amplifying pathogen abundance and accelerating transmission—and target these species for control or surveillance. Often, however, many other species that co-occur with the primary reservoirs can reduce the abundance or transmission rate of the pathogen, but these species tend to be neglected by researchers. These key features of zoonotic diseases also occur in diseases of wildlife, livestock, and plants.15 When host species differ in both the strength and direction (amplifying or diminishing) of their effects on the pathogen, it stands to reason that changes in the species composition of the host community can change the pathogen’s abundance and transmission potential (Figure 6.3). This simple concept has been instrumental in the development of theory and a rich empirical body of research on the relationship between biodiversity and infectious disease. As described in Chapter 4, humans are changing biodiversity at unprecedented rates from local to global scales.16,17 The primary drivers of native species losses, which include local extirpations and global extinctions, are habitat destruction and fragmentation, direct exploitation, pollution, displacement by exotic species, including nonnative pathogens, and climate change.18 Among these drivers, habitat destruction and fragmentation appear to be the most important and widespread.19

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Figure 6.3 The presence of opossums in Eastern forests can reduce Lyme disease exposure because opossums are highly effective groomers, removing 96.5% of larval ticks, and they are also incompetent hosts, meaning that the small percentage of ticks that survive are inefficient in transmitting infection to opossums (Keesing et al. Hosts as ecological traps for the vector of Lyme disease. Proc Biol Sci. 2009; 276(1675):3911–3919). Source: Pixabay

Anthropogenic habitat destruction and fragmentation affect some species more than others. In general, species with larger bodies, a slower pace of life, more specific habitat and dietary needs, and more animal foods in their diets tend to be more sensitive to habitat loss than are smaller, more generalist species. A parallel relationship exists for plants. The weedy species that proliferate under habitat destruction and degradation are smaller, more generalized, and with a faster pace of life, compared with the species that decline or disappear.20–22 In fact, some species increase in abundance and distribution under anthropogenic disturbance and destruction of habitat, in part because of the decline of predators and competitors and in part because of nutritional subsidies from human activities.23 Therefore, the sensitivity of different species to habitat destruction, and even the sequence of species loss (which species disappear first as biodiversity declines), can be predictable based on life history features.24–26

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Among vertebrates, the species that tend to persist and even proliferate in urbanized, suburbanized, and agricultural settings, when other components of the biota disappear, include many rodents and some songbirds.27–29 More rodents act as reservoir (amplifying) hosts of zoonotic pathogens, and more such pathogens are transmitted from rodents than from members of any other mammalian order.30 Among rodents, the species with the shortest life spans and highest reproductive rates tend to be most likely to act as zoonotic reservoirs.31 These observations—that rodents often amplify zoonotic pathogens and often proliferate when biodiversity declines—generate the expectation that zoonotic disease risk or incidence should increase when biodiversity is lost. One of the best-studied examples of changes in disease risk with changing biodiversity is Lyme disease, a tickborne zoonosis caused by the spirochete bacterium, Borrelia burgdorferi. In North America, the major vector is the blacklegged tick, Ixodes scapularis, and other species in the same genus are the main vectors in Europe, Asia, and North Africa. Larval Ixodes ticks hatch from eggs free of infection with B. burgdorferi because mother ticks are incapable of transmitting this pathogen, or most other tickborne zoonotic pathogens, to their offspring. Larval Ixodes ticks take their single blood meal from almost any mammal, ground-dwelling songbird, or lizard that they happen to encounter when seeking a host. The different host species vary dramatically in their probability of transmitting infection to the feeding larval ticks. At one extreme are white-footed mice (Peromyscus leucopus), which infect about 90% of the ticks that feed on them; at the other are species such as opossums (Didelphis virginiana), raccoons (Procyon lotor), and white-tailed deer (Odocoileus virginianus), which infect less than 5% of feeding ticks.32,33 In addition to being the most competent reservoir for zoonotic pathogens transmitted by ticks, white-footed mice are also the most permissive host for tick feeding. About half of the larval ticks attempting to feed on mice survive and feed to repletion, whereas this value is less than 5% for ticks attempting to feed on opossums.32 Numerous field studies of vertebrate community responses to habitat fragmentation and biodiversity loss find that the white-footed mouse is the most ubiquitous species and typically increases in abundance as forested landscapes are fragmented and otherwise degraded.33 As a result, fragmented landscapes, small forest patches, and low-diversity islands have repeatedly been shown to support higher densities of infected blacklegged ticks.34–37 States in the United States with low species richness in the animal community have also been shown to experience higher per capita incidence of Lyme disease in the human population, compared with states with high animal diversity.38 Small mammals that increase in abundance or proximity to humans under anthropogenic disturbance, or those that are synanthropic (regularly occupy human dwellings), are the most competent natural reservoirs for many other zoonotic diseases worldwide. For example, hantaviruses can cause severe disease of the kidneys or cardiopulmonary system, including hemorrhagic fever with renal syndrome (mostly in Asia), nephropathica

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epidemica (a similar but less virulent condition with a northern European distribution), and hantavirus pulmonary syndrome (North, Central, and South America), the latter with quite high case fatality rates. The loss of biodiversity has repeatedly been shown to be associated with increases in the abundance of infected rodents and elevated risk of human exposure to the viruses, which are transmitted to people from rodent excreta.39,40 Similarly, rodents and small, synanthropic marsupials in neotropical areas are the major reservoirs of Trypanosoma cruzi, the parasite that causes Chagas disease. This disease causes the greatest burden in disability-adjusted life-years of any parasitic disease in the Americas41 and results in a global economic burden of US$7.2 billion annually. Correlational studies show that the abundance of these reservoir species and of the triatomine bug vectors of T. cruzi increase when mammalian diversity is reduced.42,43 The loss of mammalian diversity in East African savannas, experimentally elicited by wildlife fencing, correlates with increased abundance of the most ubiquitous rodent, the pouched mouse (Saccostomus mearnsi),2,44 with a consequent increase in the overall abundance of fleas on these rodents,45 leading to the potential for increases in transmission of fleaborne illnesses with biodiversity loss. Fleas are important vectors of Bartonella bacteria,46 which cause several different types of disease in humans and of Yersinia pestis bacteria, which cause plague.47 The generality of a relationship between biodiversity loss and increased risk of pathogen transmission extends far beyond small mammals and zoonotic pathogens. The systematic review and meta-analysis by Civitello et al.48 demonstrated that the negative association between biodiversity of hosts and pathogen abundance is equally strong for diseases of wildlife and humans, for microparasites (e.g., viruses and bacteria) and macroparasites (protozoa and helminths), and for pathogens with simple and complex life cycles. Of interest is that this negative association was equally strong in experimental and nonexperimental (correlational) studies. A follow-up meta-analysis by Huang et al.49 showed that the negative relationship is equally strong for animal and plant diseases. Although in a few instances increased biodiversity does not affect, or is positively associated with, pathogen abundance, these appear to be a minority of cases.

Land Use and Land Cover Change Humans alter natural habitats through a variety of mechanisms (see Chapter 4). Sometimes the effects are diffuse and subtle, such as when humans introduce an exotic species that affects relative abundances of native species. But often the effects are more dramatic, such as when native forests are replaced by urban or suburban development or converted to agricultural fields. These examples of anthropogenic changes in land use and land cover (hereafter called land use) can influence patterns of infectious pathogen transmission in multiple ways. One mechanism by which change in land use can affect disease patterns is changes in the abundance, distribution, or behavior of species involved in maintaining and

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transmitting the pathogen. For instance, many of the effects of changing biodiversity on disease are themselves driven by changes in land use. One example of changing land use that increases pathogen transmission is the construction of dams in some tropical environments, which leads to the proliferation of the snails that act as intermediate hosts for the parasites that cause schistosomiasis. An example of changing land use that decreases pathogen transmission is the conversion of natural wetlands to agricultural fields, which can reduce breeding habitats for some Anopheles and other mosquito vectors,50 although it can also increase mosquito-borne diseases.51 The net effect of the land use conversion depends on its effects on the assemblage of species capable of amplifying or diluting pathogen transmission. When multiple species involved in maintenance and transmission are affected, and when those species are differentially influenced by environmental change, the net effect can be difficult to predict. The other major mechanism operates through changing human behavioral patterns, abundance, distribution, or physiology in response to the environmental change. Even if a change in land use has no net effect on the abundance or distribution of hosts, vectors, and pathogens, patterns of disease could be altered as a result of changes in the ways people interact with these organisms. For instance, logging in some tropical forests can increase malaria incidence by attracting human populations to otherwise sparsely populated areas where infected mosquitoes are abundant (note that this deforestation can also increase mosquito abundance at the same time).52 In contrast, by concentrating human activity in the built environment, urbanization can reduce human use of risky habitats where pathogens and vectors abound. Urbanization by itself, which increases human population density, can affect pathogen transmission profoundly but not always predictably. For instance, many human pathogens are transmitted at much higher rates when population density is high, leading to strong increases in disease incidence. However, these denser, urban human populations can also achieve a higher level of immunity than is the case in less dense, rural populations, rendering the latter more susceptible to devastating epidemics.53 Similarly, conversion of natural habitat to agriculture can promote human nutrition, which in turn can increase resistance to some infectious diseases. In some cases, a given change in land use can inhibit transmission of some infectious diseases while exacerbating others or increase disease in one population while reducing it in others, leading to a need to focus on net effects across diseases and populations.54 The impact of one key type of land use change—deforestation—on malaria incidence in the Amazon basin has been controversial, with some researchers arguing that deforestation reduces malaria55 and others that it increases malaria.51 The controversy arises in part because of difficulties in obtaining data on deforestation and disease incidence from the same places at the appropriate times. For instance, when malaria incidence data are available only at time scales much longer than the deforestation data, then actual correlations can be obscured by the mismatch between the putative cause and anticipated

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effect. To overcome this problem, Chaves et al.56 correlated the mean monthly number of malaria cases in Amazonian Brazil with monthly deforestation data obtained from the Imazon Deforestation Alert System between 2009 and 2015. They found strong, positive correlations between the number of forest patches smaller than 5 square kilometers that were deforested or degraded in a month and the number of malaria cases in that month. Based on the monthly data, the researchers also found a positive correlation between the total area deforested and the total number of malaria cases, with each square kilometer of deforestation corresponding to an additional twenty-seven new malaria cases. They chose a patch size of less than 5 square kilometers based on the observation that breeding habitat of the main vector species, Anopheles darlingi, is improved at forest edges, which are maximized in landscapes with many small forest patches. The converse of deforestation—conservation of tropical forest—also has been examined with respect to infectious diseases. Pienkowski et al.57 analyzed incidence of diarrhea, acute respiratory infection, and fever in young Cambodian children in relation to the area of forest under legal protection within 15 kilometers of a given human community. The impressive data set consisted of 35,547 households in which health and socioeconomic data were obtained, representing 1,766 communities. They found significant negative correlations between the amount of protected area near a community and both diarrhea and acute respiratory infection in children younger than 5 years old. In a separate analysis, Pienkowski et al. found that the localized loss of dense forest (but not of other forest types) was associated with increases in incidence of diarrhea, fever, and acute respiratory infection. The precise mechanisms by which extensive protected forest near a community, and reduced rates of forest loss, protect children from these infectious diseases were not examined directly by these investigators. However, they suggest that protected areas might facilitate access by local communities to forest habitats and the ecosystem services and natural resources they provide, as well as reducing exposure to zoonotic infections. Pienkowski et al. further postulated that the destruction of dense forest might curtail the ability of local habitats to regulate microbial contamination of surface water and groundwater and might increase local air pollution that accompanies biomass burning. Because their study was correlational, strong inferences on the causes of the observed patterns are difficult. Nevertheless, the broad focus on multiple infectious diseases, the large sample of communities and individuals, and the detailed conceptual model of links between protected areas, forest cover, deforestation, and human health add strongly to the value of the study. Urbanization, which is one of the most rapidly accelerating types of land use change, can also affect infectious disease in complex ways. Urbanization is often associated with improved health care infrastructure, which can reduce the burden of infectious disease.58 But urbanization can also exacerbate some infectious diseases, as has recently been shown for some Chinese cities.59 Hantaviruses, which are transmitted from rodent hosts

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throughout Eurasia and the Americas, can cause serious disease when humans are exposed to rodent excreta. In China, hemorrhagic fever with renal syndrome (HFRS), caused by two strains of hantavirus, sickened at least 1.4 million people between 1950 and 2010 and caused at least 45,000 deaths, and more than 1.2 billion people live in provinces where HFRS occurs.59 Analyzing data on HFRS incidence and urbanization between 1963 and 2010, Tian et al.59 found that epidemics were more prolonged in areas undergoing rapid urbanization than in those that were not urbanizing. They implicate two processes that might cause these patterns. One is the rapid rate of rural to urban immigration that accompanies urbanization, which Tian et al. argue provided increasing numbers of susceptible people living in conditions with poor infrastructure that are conducive to pathogen transmission. The other is the potential for urbanization to promote abundance and increased human contact rates of the two rodent hosts for these hantavirus strains, Rattus norvegicus and Apodemus agrarius. Both species are synanthropic, with R. norvegicus thriving in cities and A. agrarius mobilizing and increasing in abundance with the deforestation and farmland conversion that accompanies urbanization. Other disease consequences of urbanization include increases in risk of exposure to pathogens transmitted by mosquitoes in the genus Aedes. Aedes aegypti and Aedes albopictus are two species with almost worldwide distributions in tropical, subtropical, and temperate areas. These species can be found in “natural” (not human-dominated) habitats but reach their greatest abundances in urban areas, where they take advantage of human refuse, such as tires and garbage, that create small pools of water ideal for breeding. Urbanization can dramatically exacerbate disease risk by fostering the close juxtaposition of dense populations of mosquito vectors and human hosts, resulting in a heavy toll in the form of dengue fever, yellow fever, Zika fever, and Chikungunya fever in urban areas. Some researchers have found that urban neighborhoods occupied by residents at lower socioeconomic levels support higher densities of these mosquitoes than neighborhoods with residents at higher socioeconomic levels.60

Pollution and Altered Biogeochemical Cycles Human impacts on natural environments can affect infectious disease dynamics even when they do not involve wholesale conversion of one land cover type to another. An important example is the pollution of natural ecosystems with agricultural chemicals such as fertilizers and pesticides. Leakage of nitrogen and phosphorus from agricultural fields to various waterbodies is expected to increase pathogen transmission when the pollutants elicit population growth in vector, host, or parasite species, as is the case for herbivorous or detritivorous species and for parasites or hosts that exploit these herbivores or detritivores. In the case of pesticide pollution—for example, the runoff of insecticides from crop fields into nearby waterways—one might expect pathogen transmission to be reduced if the vectors, hosts, or parasites are themselves reduced in abundance via

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toxicity of the pesticide. However, if the pesticide causes sublethal effects in a vector or host that reduces its resistance to the parasite without reducing vector or host abundance, one might expect pathogen transmission to increase.61 In Belize, malaria parasites are transmitted to humans predominantly by Anopheles vestitipennis and Anopheles albimanus, with the former having a much higher vector competence, biting humans much more frequently, and being implicated in far more cases of malaria. Both species breed in marshes and other wetlands, but they segregate by the types of vegetation that dominate the wetlands. Where they co-occur, interspecific competition between larvae can be intense, which might contribute to the segregation of breeding habitat between the two species. An. vestitipennis is more abundant in marshes with tall macrophytes such as Typha (cattails) and in flooded forests, whereas An. albimanus tends to breed in marshes with shorter macrophytes.62 Both correlational and experimental lines of evidence indicate that enrichment with phosphorus benefits Typha at the expense of shorter macrophytes and thus strongly improves habitat quality for the more important malaria vector, Ae. vestitipennis, at the expense of Ae. Albimanus (Figure 6.4). As a consequence, landscapes dominated by agricultural fields, where phosphorus loading into wetlands is high, have increased risk of human exposure to malaria.62 Farmers in upland Belize who are adding

Figure 6.4 Cattail vegetation. Wetland systems like this one can see shifts in species composition in response to nutrient loading, which then result in altered habitat for disease-carrying mosquitoes and other species. In this way, remote agricultural practices can alter risk of disease exposure for downstream populations. Source: Courtesy of Thomas Schrider, University of Florida

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fertilizer to improve crop yields are therefore unwittingly putting their lowland compatriots at increased risk for malaria. This is an example of the unintended (and often undetected) negative health consequences of human manipulations of the environment, which is a primary focus of planetary health research. In the villages surrounding Lake Malawi, about 73% of the people and an estimated 94% of the schoolchildren are infected with flukes of the genus Schistosoma, which cause schistosomiasis, a potentially debilitating disease affecting roughly 250 million people, mostly in sub-Saharan Africa (Figure 6.5). Schistosomes use freshwater snails as their intermediate host and humans as the definitive host. Abundance of schistosomes correlates with abundance of snails; near Lake Malawi, the important snails are in the genus Bulinus. The abundance of Bulinus snails has increased dramatically in and around Lake Malawi in recent decades, and with these increases in intermediate hosts has come a strong increase in the prevalence of schistosomiasis.63 Increases in the abundance of snails are associated with the overfishing of mollusk-eating fishes and also with increased

Figure 6.5 Child walking barefoot on the shore of Lake Victoria. People contract schistosomiasis when larval forms of the parasite, released by freshwater snails, penetrate their skin during contact with infested water. Source: Photo by Andrew Amiet

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nutrient runoff and sedimentation in the lake. Intensifying agriculture in the watersheds that drain into Lake Malawi thus appears to intensify the transmission of schistosomiasis to local populations.63 Notably, the recent trend of warming waters in the lake appears to exacerbate the problem by increasing the reproductive rate of the schistosomes when in their intermediate hosts or in free-living stages.63 This last point illustrates how multiple anthropogenic drivers can interact to affect transmission of infectious diseases. As with previous examples, the net effects of multiple anthropogenic disturbances can depend on the identities and traits of the species most heavily affected and the roles they play in increasing or decreasing pathogen transmission. Predictions can be generated from experimental tests of the impacts of pollutants and other coincident changes on key species involved in pathogen transmission, and these predictions can be refined and evaluated by models and correlative approaches in the real world. Recent research suggests that intentional human activities can compensate for or even reverse the unintended exacerbation of schistosomiasis risk in tropical African systems resulting from overfishing, nutrient pollution, and climate change. Some crustaceans are known to kill and eat the snails that transmit schistosomes, to the point of potentially regulating snail populations in some freshwater systems. One of these crustaceans is the Louisiana red swamp crayfish, Procambarus clarkii, which is native to the southeastern United States and northern Mexico. This crayfish could reduce the burden of schistosomiasis at least at local levels in Africa, leading to its suggested use as a biocontrol agent.64 Unfortunately, this crayfish is highly invasive in parts of Europe, Asia, Africa, North America, and South America where it has been introduced, leading to declines of native crayfish, macrophytes, some fisheries, and water quality.65 Fortunately, a freshwater prawn, Macrobrachium vollenhoveni, that is native to African regions with high burdens of schistosomiasis, has recently been shown to prey on snail hosts for schistosomes and to reduce their transmission to humans.66 Managing freshwater ecosystems to maintain healthy populations of this native predator might not only reduce the burden of schistosomiasis but also provide a local, sustainable, high-quality food source for local communities and would not entail the release or spread of an invasive exotic species. For a detailed example from Senegal, see Planetary Health Case Studies: An Anthology of Solutions (https: //islandpress.org/books/planetary-health).

Implications for Policy and Management Traditional approaches to the abatement of human infectious diseases include deployment of medicines (such as antimicrobials), vaccines, sanitation and hygiene, and sometimes control of vector populations. These reflect the predominant historical focus on the narrow context for disease in which the obvious targets are the human host and the pathogen. Evidence is now overwhelming that human exposure to many infectious diseases is influenced by factors not well captured by the focus on proximal drivers. These

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broader drivers include climate change, biodiversity loss, land use change, pollution, and interactions between these processes. It is now evident that environmental policy and management must be considered an integral part of health policy and management. In many instances, environmental policy aimed at protecting natural resources, organisms, ecosystem processes, and habitats will also protect human health against infectious diseases. This potential benefit for human health would accompany other known health benefits that accrue from the protection of ecosystem services, as discussed throughout this book. When and how health benefits accrue when environmental protections are imposed will need to be pursued for specific policy and management efforts but should be informed by the general principles described above. Policies that provide benefits for human health and environmental health simultaneously constitute win–win situations and should be actively sought whenever possible. In some cases, tradeoffs will exist, such that a policy to promote human health comes at a cost to the environment. For example, agricultural expansions often produce strong health benefits by providing more food for more people, but these benefits often come at the expense of the natural habitats, organisms, and ecosystem services that are replaced by agricultural uses. But these tradeoffs, which often dominate thinking about contrasting environmental and health needs, are not a necessary outcome in many situations.54 Often the benefits of development projects that degrade or destroy natural habitat accrue to entirely different populations from those that experience the negative impacts.67 The benefits are often short term, whereas the costs occur over much longer periods.68 Sometimes the costs, in terms of exposure to infectious diseases, are not incorporated at all into the planning process. Clearly, the tradeoffs between human health and environmental health can disappear when the accounting of costs and benefits includes longer time scales and larger spatial scales. The spatial and temporal scales at which tradeoffs shift into co-benefits is an important research frontier. Development projects, large and small, typically involve environmental impact assessments, which allow the potential environmental costs to be projected and potentially ameliorated before development begins. Based on the principles and examples described above, we suggest that environmental impact assessments should more frequently incorporate effects on transmission of pathogens and changes to the risk of infectious diseases. Although we have focused on human diseases, the same principles apply to diseases of wildlife, livestock, and plants.2

Conclusion In this chapter, we have described general principles connecting specific types of environmental drivers to risk of human exposure to infectious diseases and how specific mediating factors convert risk into actual health effects. Key environmental drivers, such as climate change, biodiversity loss, land use change, pollution, and alteration of biogeochemical

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cycles, cause changes in the abundance, distribution, physiology, and behavior of important species involved in the transmission of both zoonotic and nonzoonotic pathogens to humans. Often, several or even many species are involved in affecting the transmission of a pathogen, and the net effect of the anthropogenic driver depends on the species involved and how they are influenced by the environmental change. Often, although not always, the environmental driver directly or indirectly increases transmission risk by favoring species that amplify risk over those that reduce it. Whether and how changes in risk of exposure to infectious diseases cause changes in human health depends on mediating factors that arise from human actions and infrastructure. Governance (including policies on vector control), technology (such as draining wetlands), behavior (e.g., local use of natural habitats), and other mediating factors can determine how strongly environmental drivers affect human health and disease. The assessment of when and how anthropogenic environmental drivers affect disease risk and how governance, technology, and behavior mediate impacts on human health is enormously complex and difficult. Rarely are these kinds of questions tractable with grand experiments that settle scientific issues. The linked natural and human systems that generate infectious diseases are big and messy, and our understandings of them must develop out of effective, responsible use of correlations and models, as well as smallerscale experiments in more controlled systems. Despite the challenges, decades of research have established that accelerating anthropogenic changes to our planet’s biophysical conditions will continue to alter our exposure to infectious diseases and drive the emergence and spread of new diseases at a faster rate. It is imperative that research in disease ecology, global disease surveillance, and planetary health impact assessments accelerate to keep pace. In a field so complex, we will never know everything we would like to know about how systems work, and there will always be contingencies. One of our challenges is to find the line between knowing everything and knowing enough to act.

Authors Richard S. Ostfeld, PhD is distinguished senior scientist at the Cary Institute of Ecosystem Studies. He has published more than 240 peer-reviewed articles, written one book (Lyme Disease: The Ecology of a Complex System, 2011, Oxford University Press), and co-edited five books as well as an annual series, The Year in Ecology and Conservation Biology. Ostfeld’s recent awards and honors include election to the American Academy of Arts and Sciences (2019) and Elected Fellow of the Ecological Society of America (2014) and of the American Association for the Advancement of Science (2013). His research focuses on ecological determinants of human risk of exposure to infectious diseases, emphasizing Lyme disease and other vector-borne infections.

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Felicia Keesing, PhD is a biologist at Bard College who studies the consequences of interactions between species, particularly as biodiversity declines. She has published about 100 articles and book chapters and received grant support from the National Geographic Society, the National Science Foundation, the Environmental Protection Agency, and the National Institutes of Health. In 2000, Keesing received a U.S. Presidential Early Career Award for Scientists and Engineers from President Clinton, and she was elected as a fellow of the Ecological Society of America in 2019.

References 1.

Jones KE, Patel NG, Levy MA, et al. Global trends in emerging infectious diseases. Nature. 2008;451(7181):990.

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Keesing F, Belden LK, Daszak P, et al. Impacts of biodiversity on the emergence and transmission of infectious diseases. Nature. 2010;468(7324):647.

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Han BA, Drake JM. Future directions in analytics for infectious disease intelligence: toward an integrated warning system for emerging pathogens. EMBO Rep. 2016;17(6):785–789.

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Ostfeld RS, Keesing F. Is biodiversity bad for your health? Ecosphere. 2017;8(3).

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Altizer S, Ostfeld RS, Johnson PT, Kutz S, Harvell CD. Climate change and infectious diseases: from evidence to a predictive framework. Science. 2013;341(6145):514–519.

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Huijben S, Paaijmans KP. Putting evolution in elimination: winning our ongoing battle with evolving malaria mosquitoes and parasites. Evol Appl. 2018;11(4):415–430.

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Rogers DJ, Randolph SE. The global spread of malaria in a future, warmer world. Science. 2000;289(5485):1763–1766.

11. Mordecai EA, Paaijmans KP, Johnson LR, et al. Optimal temperature for malaria transmission is dramatically lower than previously predicted. Ecol Lett. 2013;16(1):22– 30. 12. Paaijmans KP, Blanford S, Bell AS, Blanford JI, Read AF, Thomas MB. Influence of climate on malaria transmission depends on daily temperature variation. Proc Natl Acad Sci. 2010;107(34):15135–15139. 13. Pascual M. Climate and population immunity in malaria dynamics: harnessing information from endemicity gradients. Trends Parasitol. 2015;31(11):532–534. 14. Béguin A, Hales S, Rocklöv J, Åström C, Louis VR, Sauerborn R. The opposing effects of climate change and socio-economic development on the global distribution of malaria. Global Environ Change. 2011;21(4):1209–1214. 15. Ostfeld RS, Keesing F. Effects of host diversity on infectious disease. Annu Rev Ecol Evol Syst. 2012;43:157–182.

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16. Ripple WJ, Wolf C, Newsome TM, Hoffmann M, Wirsing AJ, McCauley DJ. Extinction risk is most acute for the world’s largest and smallest vertebrates. Proc Natl Acad Sci. 2017;114(40):10678–10683. 17. Ripple WJ, Wolf C, Newsome TM, et al. World scientists’ warning to humanity: a second notice. BioScience. 2017;67(12):1026–1028. 18. Ceballos G, Ehrlich PR, Dirzo R. Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines. Proc Natl Acad Sci. 2017;114(30):E6089–E6096. 19. Soulé ME, Orians G. Conservation Biology: Research Priorities for the Next Decade. Washington, DC: Island Press; 2001. 20. Cronin JP, Welsh ME, Dekkers MG, Abercrombie ST, Mitchell CE. Host physiological phenotype explains pathogen reservoir potential. Ecol Lett. 2010;13(10):1221–1232. 21. Cronin JP, Rúa MA, Mitchell CE. Why is living fast dangerous? Disentangling the roles of resistance and tolerance of disease. Am Nat. 2014;184(2):172–187. 22. Lacroix C, Jolles A, Seabloom EW, Power AG, Mitchell CE, Borer ET. Non-random biodiversity loss underlies predictable increases in viral disease prevalence. J R Soc Interface. 2014;11(92):20130947. 23. Becker DJ, Hall RJ, Forbes KM, Plowright RK, Altizer S. Anthropogenic resource subsidies and host–parasite dynamics in wildlife. Philos Trans R Soc Lond B Biol Sci. 2018;373(1745). 24. Cardillo M, Mace GM, Jones KE, et al. Multiple causes of high extinction risk in large mammal species. Science. 2005;309(5738):1239–1241. 25. Guillemot N, Kulbicki M, Chabanet P, Vigliola L. Functional redundancy patterns reveal non-random assembly rules in a species-rich marine assemblage. PloS One. 2011;6(10):e26735. 26.

Jiguet F, Gadot AS, Julliard R, Newson SE, Couvet D. Climate envelope, life history traits and the resilience of birds facing global change. Glob Change Biol. 2007;13(8):1672–1684.

27. Julliard R, Jiguet F, Couvet D. Common birds facing global changes: what makes a species at risk? Glob Change Biol. 2004;10(1):148–154. 28. Nupp TE, Swihart RK. Landscape-level correlates of small-mammal assemblages in forest fragments of farmland. J Mammal. 2000;81(2):512–526. 29. Rosenblatt DL, Heske EJ, Nelson SL, Barber DM, Miller MA, MacAllister B. Forest fragments in east-central Illinois: islands or habitat patches for mammals? Am Midl Nat. 1999:115–123. 30.

Han BA, Kramer AM, Drake JM. Global patterns of zoonotic disease in mammals. Trends Parasitol. 2016;32(7):565–577.

31. Han BA, Schmidt JP, Bowden SE, Drake JM. Rodent reservoirs of future zoonotic diseases. Proc Natl Acad Sci. 2015;112(22):7039–7044. 32. Keesing F, Brunner J, Duerr S, et al. Hosts as ecological traps for the vector of Lyme disease. Proc R Soc B Biol Sci. 2009;276(1675):3911–3919. 33.

Ostfeld R. Lyme Disease: The Ecology of a Complex System. New York, NY: Oxford University Press; 2011.

34. Allan BF, Keesing F, Ostfeld RS. Effect of forest fragmentation on Lyme disease risk. Conserv Biol. 2003;17(1):267–272.

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35. LoGiudice K, Ostfeld RS, Schmidt KA, Keesing F. The ecology of infectious disease: effects of host diversity and community composition on Lyme disease risk. Proc Natl Acad Sci. 2003;100(2):567–571. 36. Brownstein JS, Skelly DK, Holford TR, Fish D. Forest fragmentation predicts local scale heterogeneity of Lyme disease risk. Oecologia. 2005;146(3):469–475. 37.

Werden L, Barker IK, Bowman J, et al. Geography, deer, and host biodiversity shape the pattern of Lyme disease emergence in the Thousand Islands Archipelago of Ontario, Canada. PLoS One. 2014;9(1):e85640.

38. Turney S, Gonzalez A, Millien V. The negative relationship between mammal host diversity and Lyme disease incidence strengthens through time. Ecology. 2014;95(12):3244–3250. 39. Khalil H, Hörnfeldt B, Evander M, Magnusson M, Olsson G, Ecke F. Dynamics and drivers of hantavirus prevalence in rodent populations. Vector-Borne Zoonotic Dis. 2014;14(8):537–551. 40. Luis AD, Kuenzi AJ, Mills JN. Species diversity concurrently dilutes and amplifies transmission in a zoonotic host–pathogen system through competing mechanisms. Proc Natl Acad Sci. 2018;115(31):7979–7984. 41.

World Health Organization. Chagas disease. https://www.who.int/chagas/en/. Accessed June 2019.

42. Gottdenker NL, Chaves LF, Calzada JE, Saldaña A, Carroll CR. Host life history strategy, species diversity, and habitat influence Trypanosoma cruzi vector infection in changing landscapes. PLoS Negl Trop Dis. 2012;6(11):e1884. 43.

das Chagas Xavier SC, Roque ALR, dos Santos Lima V, et al. Lower richness of small wild mammal species and Chagas disease risk. PLoS Negl Trop Dis. 2012;6(5):e1647.

44. Keesing F, Young TP. Cascading consequences of the loss of large mammals in an African savanna. Bioscience. 2014;64(6):487–495. 45. McCauley DJ, Keesing F, Young T, Dittmar K. Effects of the removal of large herbivores on fleas of small mammals. J Vector Ecol. 2008;33(2):263–269. 46.

Gutiérrez R, Vayssier-Taussat M, Buffet J-P, Harrus S. Guidelines for the isolation, molecular detection, and characterization of Bartonella species. Vector-Borne Zoonotic Dis. 2017;17(1):42–50.

47. Gratz NG. Emerging and resurging vector-borne diseases. Annu Rev Entomol. 1999;44(1):51–75. 48.

Civitello DJ, Cohen J, Fatima H, et al. Biodiversity inhibits parasites: broad evidence for the dilution effect. Proc Natl Acad Sci. 2015;112(28):8667–8671.

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Huang ZY, Yu Y, Van Langevelde F, De Boer WF. Does the dilution effect generally occur in animal diseases? Parasitology. 2017;144(6):823–826.

50. Service M. Agricultural development and arthropod-borne diseases: a review. Rev Saude Publ. 1991;25:165–178. 51. Olson SH, Gangnon R, Silveira GA, Patz JA. Deforestation and malaria in Mancio Lima county, Brazil. Emerg Infect Dis. 2010;16(7):1108. 52. Patz JA, Graczyk TK, Geller N, Vittor AY. Effects of environmental change on emerging parasitic diseases. Int J Parasitol. 2000;30(12–13):1395–1405. 53. Diamond J. Guns, Germs, and Steel. Los Angeles: University of California Press; 1997.

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54. Myers SS, Gaffikin L, Golden CD, et al. Human health impacts of ecosystem alteration. Proc Natl Acad Sci. 2013;110(47):18753–18760. 55. Valle D, Clark J. Conservation efforts may increase malaria burden in the Brazilian Amazon. PLoS One. 2013;8(3):e57519. 56.

Chaves LSM, Conn JE, López RVM, Sallum MAM. Abundance of impacted forest patches less than 5 km2 is a key driver of the incidence of malaria in Amazonian Brazil. Sci Rep. 2018;8(1):7077.

57. Pienkowski T, Dickens BL, Sun H, Carrasco LR. Empirical evidence of the public health benefits of tropical forest conservation in Cambodia: a generalised linear mixed-effects model analysis. Lancet Planetary Health. 2017;1(5):e180–e187. 58. Dye C. Health and urban living. Science. 2008;319(5864):766–769. 59. Tian H, Hu S, Cazelles B, et al. Urbanization prolongs hantavirus epidemics in cities. Proc Natl Acad Sci. 2018;115(18):4707–4712. 60. LaDeau S, Leisnham P, Biehler D, Bodner D. Higher mosquito production in lowincome neighborhoods of Baltimore and Washington, DC: understanding ecological drivers and mosquito-borne disease risk in temperate cities. Int J Environ Res Public Health. 2013;10(4):1505–1526. 61. Rohr JR, Raffel TR, Halstead NT, et al. Early-life exposure to a herbicide has enduring effects on pathogen-induced mortality. Proc R Soc B Biol Sci. 2013;280(1772):20131502. 62.

Rejmankova E, Grieco J, Achee N, et al. Freshwater community interactions and malaria. In: Collinge SK, Ray C, eds. Disease Ecology: Community Structure and Pathogen Dynamics. New York, NY: Oxford University Press; 2006:90–104.

63. Van Bocxlaer B, Albrecht C, Stauffer JR Jr. Growing population and ecosystem change increase human schistosomiasis around Lake Malaŵi. Trends Parasitol. 2014;30(5):217–220. 64. Mkoji G, Hofkin B, Kuris A, et al. Impact of the crayfish Procambarus clarkii on Schistosoma haematobium transmission in Kenya. Am J Trop Med Hyg. 1999;61(5):751–759. 65. Global Invasive Species Database. 2015; http://www.iucngisd.org/gisd/. Accessed June 2019. 66. Sokolow SH, Huttinger E, Jouanard N, et al. Reduced transmission of human schistosomiasis after restoration of a native river prawn that preys on the snail intermediate host. Proc Natl Acad Sci. 2015;112(31):9650–9655. 67. Myers SS. Planetary health: protecting human health on a rapidly changing planet. Lancet. 2017;390(10114):2860–2868. 68.

Whitmee S, Haines A, Beyrer C, et al. Safeguarding human health in the Anthropocene epoch: report of the Rockefeller Foundation–Lancet Commission on Planetary Health. Lancet. 2015;386(10007):1973–2028.

7 Global Environmental Change and Noncommunicable Disease Risks Howard Frumkin and Andy Haines

Noncommunicable diseases (NCDs), principally cardiovascular diseases, cancers, chronic respiratory diseases, diabetes, and mental health conditions, together with neurologic, endocrine, gastrointestinal, renal, allergic, and autoimmune disorders, have commanded increasing attention in recent years, and with good reason. These diseases kill more than 40 million people globally each year, accounting for 71% of global deaths (Figure 7.1).1,2 Among the victims are more than 14 million people who, in the words of the World Health Organization (WHO), “die too young”—that is, between the ages of 30 and 70 years.3 NCDs also accounted for 21 of the top 30 causes of age-standardized years lived with disability (YLDs) in 2016, or 80.6% (95% confidence interval [CI], 78.2–82.5) of YLDs, according to the Global Burden of Disease study.4 In this chapter, we look at NCDs through a planetary health lens. Three aspects of NCDs are especially salient. First, they are not only, or even mostly, a problem of wealthy nations. Low- and middle-income countries (LMICs) account for 86% of the burden of premature deaths from NCDs,3,5 reflecting what has been known for nearly half a century as the epidemiologic transition.6 Second, the economic implications of NCDs are substantial, with a projected cost to the global economy of $47 trillion over the next 20 years.7 Particularly in LMICs, NCDs slow economic development and trap millions in poverty.8,9 Third, many risk factors for NCDs are environmental in origin or may be influenced by the environment. For example, about 50% of the disease burden from chronic obstructive pulmonary disease and about one quarter of the

165

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Figure 7.1 Proportion of global deaths under the age of 70, by cause of death, 2012 (top) and proportion of NCD deaths attributable to different disease categories (bottom). Source: World Health Organization. Global Status Report on Non-Communicable Diseases, 2014. 2014. WHO/NMH/NVI/15.1. https://www.who.int/nmh/publications/ncd-status-report-2014/en/

ischemic heart disease burden have been attributed to environmental factors, particularly air pollution.10-12 However, NCD prevention and treatment strategies routinely neglect environmental drivers and focus narrowly on clinical interventions or behavior changes related to tobacco, diet, physical activity, and alcohol. These are essential but insufficient; the failure to address upstream drivers of NCDs probably limits the impact of more downstream interventions.13 Together, these make NCDs a central concern for planetary health.14

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This chapter builds on other chapters in this book, outlining pathways by which global environmental changes (GECs), and the driving forces responsible for them, influence the risks of NCDs. We consider five pathways: energy, air pollution, and climate change (see also Chapters 10 and 12); urbanization (see also Chapter 13); food, nutrition, and agriculture (see also Chapter 5); persistent environmental chemicals (see also Chapter 14); and biodiversity loss (including fishery depletion; see Chapter 4). Rather than repeating what is in those chapters, our goal here is to provide additional insights specific to NCDs.

The Impact of Global Changes on NCDs Energy, Air Pollution, and Climate Change A principal driver of GEC is the combustion of the fossil fuels coal, oil, and gas, with coal having the largest effect. The dependence on fossil fuels for energy is a leading source of air pollution.15 It is also the dominant contributor to climate change. Each of these—air pollution and climate change—represents a set of pathways linking energy use to NCDs.

Air Pollution Air pollution related to fossil fuel combustion is a major contributor to morbidity and mortality worldwide (Figure 7.2).11,12 As described in Chapter 12, key pollutants include

Figure 7.2 Coal-fired power plants such as this one are major sources of greenhouse gas emissions and air pollution. The air pollution, in turn, is responsible for large burdens of cardiovascular and respiratory disease. Source: Pixabay

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fine particulate matter (PM), ozone, oxides of nitrogen, oxides of sulphur, hydrocarbons, and metals, many of which are related to each other through complex atmospheric chemistry. The Global Burden of Disease (GBD) Study estimates that ambient (outdoor, as opposed to within households) fine particulate matter (PM2.5) alone ranked fifth globally as a mortality risk factor in 2015, accounting for an estimated 4.2 million deaths (7.6% of global deaths) and 103.1 million disability-adjusted life-years (DALYs) (4.2% of global DALYs) in 2015.16,17 These deaths are not uniformly distributed; the greatest burdens are in China and India (with about 1.1 million annual deaths each), Russia (137,000), Pakistan (135,000), and Bangladesh (122,000). Of note, the WHO estimates of the burden of ambient air pollution, based on a different method, are somewhat lower than those of the GBD Study: 3 million deaths and 85 million DALYs.18 Without a rapid transition toward clean renewable sources of energy, economic growth is projected to increase this burden substantially in some regions, such as southeast Asia, in the coming decades.19 The excess mortality from PM exposure is attributable primarily to NCDs: ischemic heart disease, cerebrovascular disease, chronic obstructive pulmonary disease, and lung cancer, with a small proportion of excess deaths—perhaps one in ten—due to lower respiratory infection. Air pollution exposure, especially to PM, may aggravate cardiac arrhythmias20 and heart failure,21 as well as increasing the risk of type 2 diabetes.22 PM exposure may also be neurotoxic across the lifespan, contributing to neurodevelopmental delay in children and to cognitive decline in older adults,23 although the evidence of these links is still emerging. Ozone is formed from atmospheric precursors—hydrocarbons (methane and volatile organic compounds) and oxides of nitrogen—many of which are combustion products. Like PM, ozone is also associated with excess mortality, although lesser in magnitude than PM.24 In the GBD data, exposure to ozone caused an additional 254,000 (95% CI, 97,000–422,000) deaths and a loss of 4.1 million (95% CI, 1.6 million–6.8 million) DALYs from chronic obstructive pulmonary disease in 2015.16 More recent estimates using updated exposure response relationships suggest at least a fourfold higher burden, with 1.04–1.23 million respiratory deaths in adults attributable to long-term ozone exposures. The largest increases in estimated attributable mortality were in northern India, southeast China, and Pakistan.25 The association between ozone exposure and mortality seems to relate both to short-term high exposures and to long-term exposure.25,26 Short-term ozone exposure also triggers exacerbations of airway disease (asthma and chronic obstructive pulmonary disease), accounting for substantial numbers of emergency room visits and hospitalizations.27 A 2019 study assessed the overall global mortality from fossil fuel combustion, using a global atmospheric chemistry–climate model and data from a large number of cohort studies in many countries.28 The study estimated that fossil fuel combustion is responsible

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for 3.61 (2.96–4.21) million excess deaths per year worldwide from outdoor air pollution. This excess mortality could be as high as 5.55 (4.52–6.52) million per year if additional nonfossil anthropogenic emissions (e.g., from agriculture and domestic sources) are included. A phaseout of fossil fuel combustion could not only avert these deaths; because aerosols from this source affect the hydrologic cycle, leading to reduced rainfall over densely populated parts of India, China, Central America, West Africa, and the Sahel, water and food insecurity in these regions would be reduced. This highlights the health benefits that a shift to renewable energy can deliver.

Climate Change Climate change presents another, overlapping set of pathways through which energy use, and resulting GECs, affect health29 and NCDs in particular.30 Multiple direct and indirect mechanisms are described in Chapter 10. Here, we mention several additional links relevant to NCDs. Climate-related disasters interrupt the continuity of health care that is essential for many NCDs. A systematic review of the impacts of cyclone, flood, and storm disasters on NCD-related health care found that people with cancer, diabetes, and cardiovascular diseases suffered exacerbations of their health problems after such disasters. This was due to a range of factors including disruption of transport, weakened health systems including drug supply chains, loss of power, and evacuations of populations.31 Another pathway operates through heat. The increasing hot weather that comes with climate change is associated with increases in mortality, emergency presentations, and hospital admissions due to cardiovascular, respiratory, and renal disease.29 Increased heatrelated mortality with advancing climate change will probably outweigh any declines in cold-related mortality, particularly in tropical and subtropical regions and in southern Europe.29,32 Heat is not the only pathway through which climate change may increase cardiovascular disease risk. First, hot weather is associated with sleep disturbance,33 which in turn is a risk factor for cardiovascular disease.34 Second, hot weather is associated with a reduction in physical activity,35 and reduced physical activity is a risk factor for cardiovascular disease.36 Cold weather also reduces physical activity, so in cold regions that become warmer, physical activity may increase. The net effect globally is likely to be negative.35 Third, rising sea levels, together with excessive groundwater withdrawals, land use changes, agricultural practices, and other factors, can lead to saline intrusion of groundwater in coastal areas.37 This, in turn, increases salt intake of affected populations. Higher salt intake via drinking water is associated with increased blood pressure, although the effect is not large,38 and one Bangladeshi study found a paradoxical effect, perhaps because the more saline drinking water also carried high (and protective) levels of calcium

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and magnesium.39 Higher salt intake may also affect health during pregnancy. A study in coastal Bangladesh suggested that pregnant women were exposed to more than twice the WHO/Food and Agriculture Organization recommended limits for salt intake in drinking water and that this increased the risk of preeclampsia and gestational hypertension.40 On the other hand, warmer weather may be linked to lower blood pressure, suggesting that warming in some areas may reduce cardiovascular disease risk.41 Climate change may also aggravate cancer risk. First, as noted above, physical activity declines with heat; sedentariness increases cancer risk. Second, there is evidence that climate change increases production of aflatoxin, a liver carcinogen.42 Climate change may increase the risk of kidney disease. Kidney stone formation seems to vary with temperature, perhaps due to relative dehydration and resulting urinary concentration.43 Chronic kidney disease of unknown origin has been observed in working populations in hot places, such as among sugarcane cutters in Nicaragua,44 although a recent systematic review found inconsistent associations between heat and chronic kidney disease.45 Climate change may affect NCD risk through a variety of nutritional pathways. These are discussed below, in the section on food and nutrition. Of note, the two sets of pathways discussed here that link energy and NCDs—through air pollution and through climate change—are not independent. Certain air pollutants function as short-lived climate pollutants and promote climate change while also threatening health via direct toxic effects (e.g., black carbon, tropospheric ozone) or (in the case of methane) by giving rise to tropospheric ozone.46

Urbanization The city has become the prototypical human habitat, and although urbanization is not a classic form of environmental change, it represents a defining global shift in both demographic and land use patterns. As explored in Chapter 13, more than half of humanity now lives in urban areas, and with nearly all global population growth occurring in cities, that proportion is expected to reach two thirds by 2050.47 Much attention focuses on megacities of more than 10 million people, such as Mexico City, São Paulo, Cairo, Lagos, Karachi, Delhi, Manila, and Jakarta, but nearly half the world’s urban dwellers live in a growing number of smaller cities with fewer than 500,000 inhabitants, where populations are growing even faster than in megacities.48 Fast-growing cities of the Global South confront a range of health and environmental challenges, including deficiencies in basic infrastructure (piped water, sewage, solid waste management, electricity, transportation, housing) and hazardous exposures (extremely poor air quality, noise, and unsafe roadways), compounding problems of poverty, poor governance, and inadequate social services.49 In wealthy settings, especially in North

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America, Europe, and Australia but increasingly in other regions, urban environmental health challenges reflect excessive automobile dependence, with associated urban sprawl and resulting problems such as poor air quality, sedentary lifestyles, and injury risk.50 Finally, some problems are common to cities in both wealthy and poor nations; these include extreme social stratification, neighborhoods of concentrated poverty, insufficient green space, food deserts, and vulnerability to disasters.

Impact of Urbanization on GEC (and on NCD Risk) Economic activity in cities generates between 70% and 85% of global GDP and about 75% of energy-related greenhouse gas (GHG) emissions.51,52 Although cities offer major opportunities to reduce per capita environmental impacts relative to rural areas because of their short travel distances, reduced per capita living space, and efficiencies in delivering goods and services, poorly designed cities forfeit these potential advantages. Moreover, because cities source most of their energy and goods from outside the city limits, a full accounting of the impact of cities on GEC extends well beyond city boundaries.53 Several pathways are well documented, and they often feature contributions both to GEC and to NCDs. First, the combination of automobile-dependent transportation systems and urban sprawl, and the concentration of industrial and domestic energy needs, means that large quantities of fossil fuels are burned in and near metropolitan areas. This contributes to climate change, as well as to regional air pollution. Urban air quality is often poor, especially in the cities of low- and middle-income countries. According to the WHO, more than 80% of people living in urban areas that monitor air pollution are exposed to pollutant levels above WHO guidelines, and 98% of cities in LMICs with more than 100,000 inhabitants do not meet WHO air quality limits.54 Globally, 25% of urban ambient PM air pollution comes from traffic, 15% from industrial activities, 20% from domestic fuel burning, 22% from unspecified sources of human origin, and 18% from natural dust and salt.55 In cities where indoor solid fuels are commonly used, exposure to ambient air pollution is compounded by household air pollution exposure, an important source of black carbon, a powerful short-lived climate pollutant.56 The contributions of air pollution to NCDs are discussed above. Second, automobile-dependent transportation systems contribute both to GHG emissions and to sedentary lifestyles, as walking, cycling, and transit give way to vehicular travel (Figure 7.3). As described in Chapter 13, attributes of cities that predict greater physical activity include residential and intersection density, land use mix, ample and accessible public transport, attractive streetscapes, pedestrian and bicycle infrastructure, and parks. In one study, the difference in physical activity between the most and least activity-friendly neighborhoods ranged from 68 to 89 minutes per week (of a recommended total of 150 minutes per week).57 Sedentary lifestyles increase the risk of, and

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Figure 7.3 Automobile dependence in sprawling cities contributes to NCDs through reduced air quality, reduced physical activity, stress, and greenhouse gas emissions. Source: AtlantaCitizen (Wikimedia), Creative Commons, license CC BY-SA 3.0

physical activity is protective against, a range of NCDs including cardiovascular disease, some cancers, hypertension, obesity, some mental illnesses, osteoporosis, gallbladder disease, and other NCDs.58,59 The links between automobile dependency, sedentary behaviors, and GHG emissions may be bidirectional, as increasing obesity makes walking more difficult and may be associated with higher transport-related GHG emissions.60 Finally, several common features of urban life are indirectly linked to GECs but affect NCD risk.

Noise Noise is a common exposure in cities due to traffic, machinery, and other sources (which are also GEC contributors). A switch to electric vehicles, as leading cities are now implementing, will have as one of its benefits significant noise reductions. Noise is a stressor that contributes to a range of NCDs, including hypertension, cardiovascular disease, anxiety, sleep disturbance, and hearing loss.61

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Disconnect

from

Nature

and

Greenspace

City living may entail reduced opportunity for contact with nature and greenspace relative to rural areas. Such “salutogenic” exposure reduces the risk of obesity,62 diabetes, hypertension, and hyperlipidemia,63 depression and anxiety,64 and cardiovascular mortality,65 although the quality of evidence varies.

Crowding Crowding is another common feature of urban life, especially in impoverished parts of cities. Although crowding is difficult to define with precision and is context dependent,66 it is associated with similar cardiovascular and mental health effects as noise. Children may be especially susceptible to the effects of both noise and crowding.67,68

Inadequate Housing Inadequate housing is also a problem for many cities, especially those undergoing rapid growth and those in poor nations. Substantial portions of urban populations live in slums—more than half the population of cities such as Nairobi, Mumbai, and Mexico City, totaling an estimated 881 million people globally and rising.69 In such settings, the effects of inadequate housing—chronic stress, contaminated indoor air due to the use of solid fuels, exposure to temperature extremes, injury risks, and more—are amplified by failures of community infrastructure and health services. Respiratory disease and mental disorders are likely results, although few studies have examined the burden of NCDs in slums.69

Impact of GECs on Urbanization (and on NCD Risk) Conversely, GECs exert impacts on cities (and on urban health, including NCD risk). First, as discussed in Chapter 8, droughts, floods, and other environmental disruptions propel rural-to-urban migration, a pattern documented across the Global South.70,71 The resulting contribution to rapid urban growth intensifies such problems as air pollution, crowding, noise, and strained infrastructure and services. Second, environmental change may particularly threaten cities, through such pathways as heat (amplified by the urban heat island effect),72 flood risk,73 water scarcity,73 and diminished air quality.74 These vulnerabilities may increase the risk of NCDs such as cardiopulmonary disease (from heat and reduced air quality) and mental illness (from heat and disasters) for people in urban areas. This risk is especially pertinent in poor cities such as those in the Global South, which lack the infrastructure needed for resilience,75 and particularly for people in informal settlements, because of their location (e.g., flood plains, steep slopes) and their lack of infrastructure.76

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There are complex social, economic, cultural, and physical determinants of NCDs in urban environments. Improving understanding of these risks is a priority for research.77 The challenge is to provide housing and infrastructure that support health and livelihoods, particularly in rapidly growing cities in LMICs, while avoiding the costly errors of some wealthy cities. Transforming existing cities so that they flourish at much lower levels of environmental impact is a major policy challenge.

Food, Nutrition, and Agriculture The relationships between GECs, diet, nutrition, and NCDs are complex and multidirectional. Like cities, food systems both contribute to environmental change and are vulnerable to its effects. Here we build on Chapter 5, discussing three examples of interacting processes. First, the global dietary transition, featuring growing demand for both animal products and processed foods, has direct consequences for the risk of NCDs, as well as environmental consequences that indirectly affect this risk. Second, environmental change affects agricultural productivity, threatening nutritional status in some regions, with implications for NCDs. Third, environmental change affects the nutritional content of some foods, with implications for NCDs.

Global Dietary Transition The global dietary transition has been underway for several decades.78 It is marked by consumption of energy-dense, less diverse, and increasingly processed foods, including animal products, oils and fats, refined carbohydrates, and sugar-sweetened beverages and by behavioral changes such as increased snacking and increasing eating outside the home. This dietary transition is not an isolated phenomenon; a Lancet Commission in 2019 identified a global syndemic of obesity, undernutrition, and climate change, driven by changes in food and agriculture, transportation, urban design, and land use79—a systems analysis that aligns closely with the planetary health framework. This dietary pattern has direct implications for NCDs, promoting obesity, cardiovascular disease, diabetes, and some cancers.78,80–83 It also has environmental impacts—GHG emissions, deforestation, water use, and others—that, in turn, may loop back to exert indirect impacts on human health. These links are discussed in detail in Chapter 5.

Impact of Climate Change on Agricultural Productivity A second food-related link between GECs and NCDs is the effect of climate change on agricultural productivity. As described in Chapter 5, the mechanisms include the loss of arable land and soil, depletion of fresh water, harmful changes in populations of pollinators and pests, disruptive weather, and impacts of pollutants.

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One clear pathway from reduced crop production to NCDs is an increased risk of childhood undernutrition and stunting.84 The prevalence of childhood stunting in Asia fell dramatically from 49% in 1990 to 28% in 2010, but in Africa the stunting prevalence became stuck at about 40% in 1990, suggesting a worrisome level of vulnerability in Africa.85 Early-life undernutrition and stunting have serious implications for cognitive development, long-term economic prospects, and subsequent generations.86 Some evidence suggests that undernutrition in early life increases the risk of obesity, metabolic syndrome, cardiovascular disease, and diabetes in adulthood.87,88 A modeling study of the effects of climate change on crop yield by 2050 suggested a net annual increase of about 529,000 premature deaths with no climate change, mostly in South and East Asia and mostly due to NCDs.89 Reductions in fruit and vegetable consumption were the major contributor to increased mortality. Decreased caloric intake was projected to increase deaths related to undernutrition, but these were approximately balanced by reduced deaths from overweight and obesity.

Impact of Climate Change on Crop Nutritional Levels A third food-related pathway from GECs to NCDs is the effect of climate change on the nutritional value of crops, a phenomenon described in detail in Box 5.2. Elevated ambient CO2 reduces the level of proteins, several B vitamins, and micronutrients including calcium, potassium, zinc, and iron in many food crops.90 The impacts of these changes on NCDs are not fully understood, but some potential risks are clear: the increased risk of hypertension, lipid disorders, and coronary heart disease that follows a shift from dietary protein to carbohydrates,91 and the increased risk of neural tube defects from dietary folate deficiency.92 Oil palm cultivation exemplifies the complex relationships between global environmental change, diet, nutrition, and NCDs.93 Production is increasing as a result of demand for biofuels in Europe and food in India, Indonesia, and China. To clear tropical forests in Indonesia for palm oil (as well as timber) production, fire is commonly used; the resulting smoke, with its high level of fine PM, results in more than 30,000 deaths in Indonesia, Malaysia, and Singapore in a typical year94 and as many as 100,000 in a bad year.95 Tropical deforestation for the production of palm oil also contributes to climate change and biodiversity loss. And with its highly saturated fatty acid content, dietary palm oil may increase the risk of metabolic syndrome and heart disease, although evidence on this point is equivocal.96,97 For a detailed case study focused on addressing biomass fires in Indonesia, see Planetary Health Case Studies: An Anthology of Solutions (https://islandpress .org/books/planetary-health). Two additional pathways from GECs to NCDs are the effects of fishery depletion and pollinator loss. These are discussed below in the section on biodiversity.

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Persistent Chemicals in the Environment Another feature of the Anthropocene has been widespread contamination of the global environment by chemicals,10,98 a phenomenon explored in Chapter 14. Although many features of this contamination, from its extent to its full impacts on human health, are not fully understood, the links with NCDs are coming into sharper focus. Two examples are illustrative: endocrine disrupters and metals.

Endocrine Disrupters Endocrine disrupters include diverse classes of chemicals that affect endocrine pathways, either blocking or activating receptors in sex hormone, thyroid, or other pathways. Many endocrine disrupters are synthetic organic chemicals such as polychlorinated biphenyls, bisphenols (such as bisphenol A), organochlorine pesticides, brominated flame retardants, and perfluorinated substances (perfluorooctanoic acid and perfluorooctane sulfonate). Many such chemicals persist in the environment over long periods of time (and are therefore called persistent organic pollutants [POPs]). Although POPs are chemically quite variable, they share several features. First, they are widely distributed in global ecosystems. Second, human exposure is widespread. Third, they are associated with NCD risk. The first two points are discussed in Chapter 4; here, we focus on the risk of NCDs. Evidence suggests that environmental chemical exposures play a role in several NCDs through both epigenetic and nonepigenetic mechanisms.99 POP exposure has been associated with metabolic conditions such as adiposity, insulin resistance, and dyslipidemias, although evidence is inconsistent.100–103 POP exposure has also been associated with risk of some cancers, especially non-Hodgkin lymphoma104 and hormone-responsive cancers such as those of breast, ovaries, and prostate; there is considerable animal evidence, but human epidemiologic evidence is less definitive.105 POPs may also increase risks of thyroid disease, neurobehavioral disorders, and reproductive dysfunction.105 For each of these outcomes, the role of ambient environmental contamination relative to more intense exposures, such as in the workplace, remains to be defined.

Metals Metals are a second example of widespread chemical contamination with relevance to NCDs. Human exposure to metals is typically a local phenomenon: the child who consumes lead from aging paint in substandard housing or the worker exposed to mercury in artisanal gold mining. However, more dispersed mobilization of metals has occurred, with impacts that are regional, if not global. For example, in China, industrial activity, mining, and the use of inadequately treated wastewater for irrigation have contaminated soil across large portions of the country with lead, cadmium, chromium, and other metals.106

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Approximately 250,000 square kilometers of farmland—an area equivalent to the arable farmland of Mexico—is contaminated, and in 2017 Chinese officials were reported as designating 35,000 square kilometers of farmland as too polluted to permit any agricultural use.107 As another example, mercury emissions have been a feature of coal combustion since the dawn of the Industrial Revolution. Mercury contamination is concentrated near point sources such as power plants, smelters, and cement, iron, and steel plants, but this is also a global phenomenon, as the mercury in air emissions travels great distances, even intercontinentally, before settling back to Earth.108 The metals, collectively, contribute to a number of NCDs, including neurobehavioral abnormalities (lead, mercury), cardiovascular disease (lead, cadmium), renal disease (lead, cadmium), and some cancers (arsenic, chromium).109

Biodiversity Loss Biodiversity loss has accelerated dramatically during the Anthropocene,110 with species extinctions probably occurring at 1,000 times baseline rates.111 Two examples of biodiversity loss—pollinator loss and fishery depletion, both introduced in Chapter 4 and explored further in Chapter 5—have particular implications for NCDs. Because many food crops depend on insect pollinators, pollinator loss can threaten the production of fruits, vegetables, legumes, nuts, and seeds, the food groups most highly prioritized in the “planetary health diet.”112 Although evidence is still accumulating, diets high in these foods seem to protect against a range of NCDs, including ischemic heart disease, diabetes, stroke, and some cancers.113–117 Similarly, eating fish (or fish products such as cod liver oil) protects against a range of NCDs including ischemic heart disease,118 some cancers,119 arthritis,120 and, perhaps, depression,121,122 dementia,123 diabetes,124 and childhood asthma.125 (The strength of the evidence varies across these different NCDs.) As noted in Chapter 5, some studies have projected the impact of biodiversity loss on NCD incidence and mortality. According to one estimate, a 50% loss of pollination could cause about 700,000 additional deaths worldwide each year, mostly because reduced fruit, vegetable, nut, and seed consumption would increase ischemic heart disease and stroke incidence.126 Similarly, if current trajectories of declining fish catches continue, populations that rely on fish could confront shortages. An estimated 11% of the global population could be at risk of zinc, vitamin A, and iron deficiency, and 19% of the global population could be at risk of vitamin B12 and DHA omega-3 fatty acid deficiency.127 These shortfalls are associated with a range of NCDs. For example, zinc deficiency may increase the risk of inflammatory bowel disease,128 diabetes,129 and metabolic syndrome,129 vitamin A deficiency causes visual abnormalities,130 and vitamin B12 deficiency causes anemia and a range of neurologic and psychiatric disorders.131

Figure 7.4 This infographic, from the NCD Alliance, emphasizes the opportunities to reduce noncommunicable diseases in the course of achieving the Sustainable Development Goals. Source: NCD Alliance

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Conclusions The Importance of Systems Understanding Although the five aspects of GEC discussed here—energy, air pollution, and climate change; urbanization; food, nutrition, and agriculture; the deposition of persistent chemicals in the environment; and biodiversity loss—were presented in separate discussions, they are by no means distinct. As Barry Commoner’s First Law of Ecology reminds us, everything is connected to everything—a foundation of planetary health that is highly relevant to the links between GECs and NCDs. To understand these links fully, we need to consider their interconnections. For example, energy, pollution, and biodiversity are linked. Heavy reliance on petroleum as an energy source results in contamination of marine environments by petroleum-derived pollutants, which are toxic to developing fish, compounding other threats to fisheries.132 Another example is the link between urbanization and food systems. Rural-to-urban migration in LMICs is associated with rapid changes in dietary patterns, including the adoption of Western-style processed foods. One study found the obesity prevalence in Accra to be four to five times higher, and the diabetes prevalence two to three times higher, than in rural Ghana.133 The various pathways through which GECs affect NCD risk are interrelated in complex ways, and solutions must take account of those complexities.

Planetary Health: Reducing NCD Risk and Achieving Environmental Sustainability Although GECs contribute to NCD risk, the association is not just about risk. Precisely because GECs contribute to NCDs, there is great potential to prevent NCDs through policies, technologies, and interventions that reduce GHG emissions and other causes of GECs; the many opportunities to fight NCDs by addressing GECs are well documented.134-136 Chapter 18 discusses how clean, renewable energy sources can replace fossil fuels; how cities can be reimagined; how the food system, from farm to table, can be transformed; how chemists can design molecules that are less persistent, less toxic, and functional; and how land, water, and other ecosystem components can be managed sustainably, all in ways that reduce the rising tide of global NCDs and the degradation of Earth systems (Figure 7.4). GECs and NCDs share many root causes, offering the exciting promise of far-reaching common solutions.

Authors Howard Frumkin, MD, DrPH is professor emeritus of environmental and occupational health sciences, and former dean, at the University of Washington School of Public Health.

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Sir Andy Haines, MD is professor of environmental change and public health at the Centre on Climate Change and Planetary Health of the London School of Hygiene and Tropical Medicine. He has had a longstanding interest in the effects of global environmental change on health and policies to address them. He has been a member of the Intergovernmental Panel on Climate Change on three occasions and was chair of the Rockefeller Foundation Lancet Commission on Planetary Health.

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100. Taylor KW, Novak RF, Anderson HA, et al. Evaluation of the association between persistent organic pollutants (POPs) and diabetes in epidemiological studies: a national toxicology program workshop review. Environ Health Perspect. 2013;121(7):774–783. 101. Jaacks LM, Staimez LR. Association of persistent organic pollutants and non-persistent pesticides with diabetes and diabetes-related health outcomes in Asia: a systematic review. Environ Int. 2015;76:57–70. 102. Lee DH, Porta M, Jacobs DR Jr, Vandenberg LN. Chlorinated persistent organic pollutants, obesity, and type 2 diabetes. Endocr Rev. 2014;35(4):557–601. 103. Yang C, Kong APS, Cai Z, Chung ACK. Persistent organic pollutants as risk factors for obesity and diabetes. Curr Diab Rep. 2017;17(12):132. 104. Freeman MD, Kohles SS. Plasma levels of polychlorinated biphenyls, non-Hodgkin lymphoma, and causation. J Environ Public Health. 2012;2012:258981. 105. Gore AC, Chappell VA, Fenton SE, et al. EDC-2: the Endocrine Society’s second scientific statement on endocrine-disrupting chemicals. Endocr Rev. 2015;36(6):E1–e150. 106. Khan S, Cao Q, Zheng YM, Huang YZ, Zhu YG. Health risks of heavy metals in contaminated soils and food crops irrigated with wastewater in Beijing, China. Environ Pollut. 2008;152(3):686–692. 107. The most neglected threat to public health in China is toxic soil. Economist. 2017. http://www.economist.com/news/briefing/21723128-and-fixing-it-will-be-hard-andcostly-most-neglected-threat-public-health-china. Accessed April 2020. 108. Selin NE. Global biogeochemical cycling of mercury: a review. Annu Rev Env Resour. 2009;34(1):43–63. 109. Nordberg GF, Fowler BA, Nordberg M, eds. Handbook on the Toxicology of Metals. 4th ed. San Diego, CA: Academic Press; 2015. 110. Newbold T, Hudson LN, Arnell AP, et al. Has land use pushed terrestrial biodiversity beyond the planetary boundary? A global assessment. Science. 2016;353(6296):288–291. 111. Pimm SL, Jenkins CN, Abell R, et al. The biodiversity of species and their rates of extinction, distribution, and protection. Science. 2014;344(6187). 112. Willett W, Rockström J, Loken B, et al. Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet. 2019;393(10170):447–492. 113. Afshin A, Micha R, Khatibzadeh S, Mozaffarian D. Consumption of nuts and legumes and risk of incident ischemic heart disease, stroke, and diabetes: a systematic review and meta-analysis. Am J Clin Nutr. 2014;100(1):278–288. 114. Aune D, Giovannucci E, Boffetta P, et al. Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality: a systematic review and doseresponse meta-analysis of prospective studies. Int J Epidemiol. 2017;46(3):1029–1056. 115. Wang X, Ouyang Y, Liu J, et al. Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response metaanalysis of prospective cohort studies. BMJ. 2014;349:g4490. 116. Miller V, Mente A, Dehghan M, et al. Fruit, vegetable, and legume intake, and cardiovascular disease and deaths in 18 countries (PURE): a prospective cohort study. Lancet. 2017;390(10107):2037–2049. 117. Boffetta P, Couto E, Wichmann J, et al. Fruit and vegetable intake and overall cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC). J Natl Cancer Inst. 2010;102(8):529–537.

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118. Rangel-Huerta OD, Gil A. Omega 3 fatty acids in cardiovascular disease risk factors: an updated systematic review of randomised clinical trials. Clin Nutr. 2018;37(1):72–77. 119. Lee JY, Sim TB, Lee JE, Na HK. Chemopreventive and chemotherapeutic effects of fish oil derived omega-3 polyunsaturated fatty acids on colon carcinogenesis. Clin Nutr Res. 2017;6(3):147–160. 120. Senftleber NK, Nielsen SM, Andersen JR, et al. Marine oil supplements for arthritis pain: a systematic review and meta-analysis of randomized trials. Nutrients. 2017;9(1). 121. Yang Y, Kim Y, Je Y. Fish consumption and risk of depression: epidemiological evidence from prospective studies. Asia Pac Psychiatry. 2018;10(4):e12335. 122. Grosso G, Micek A, Marventano S, et al. Dietary n-3 PUFA, fish consumption and depression: a systematic review and meta-analysis of observational studies. J Affect Disord. 2016;205:269–281. 123. Wu S, Ding Y, Wu F, Li R, Hou J, Mao P. Omega-3 fatty acids intake and risks of dementia and Alzheimer’s disease: a meta-analysis. Neurosci Biobehav Rev. 2015;48:1–9. 124. Zhou Y, Tian C, Jia C. Association of fish and n-3 fatty acid intake with the risk of type 2 diabetes: a meta-analysis of prospective studies. Br J Nutr. 2012;108(3):408–417. 125. Yang H, Xun P, He K. Fish and fish oil intake in relation to risk of asthma: a systematic review and meta-analysis. PLoS One. 2013;8(11):e80048–e80048. 126. Smith MR, Singh GM, Mozaffarian D, Myers SS. Effects of decreases of animal pollinators on human nutrition and global health: a modelling analysis. Lancet. 2015;386(10007):1964–1972. 127. Golden CD, Allison EH, Cheung WW, et al. Nutrition: fall in fish catch threatens human health. Nature. 2016;534(7607):317–320. 128. Ohashi W, Fukada T. Contribution of zinc and zinc transporters in the pathogenesis of inflammatory bowel diseases. J Immunol Res. 2019;2019:8396878. 129. Ruz M, Carrasco F, Rojas P, Basfi-Fer K, Hernandez MC, Perez A. Nutritional effects of zinc on metabolic syndrome and type 2 diabetes: mechanisms and main findings in human studies. Biol Trace Elem Res. 2019;188(1):177–188. 130. Wiseman EM, Bar-El Dadon S, Reifen R. The vicious cycle of vitamin a deficiency: a review. Crit Rev Food Sci Nutr. 2017;57(17):3703–3714. 131. Shipton MJ, Thachil J. Vitamin B12 deficiency: a 21st century perspective. Clin Med. 2015;15(2):145–150. 132. Cherr GN, Fairbairn E, Whitehead A. Impacts of petroleum-derived pollutants on fish development. Annu Rev Anim Biosci. 2017;5(1):185–203. 133. Agyemang C, Meeks K, Beune E, et al. Obesity and type 2 diabetes in sub-Saharan Africans: is the burden in today’s Africa similar to African migrants in Europe? The RODAM study. BMC Med. 2016;14(1):166. 134. Whitmee S, Haines A, Beyrer C, et al. Safeguarding human health in the Anthropocene epoch: report of the Rockefeller Foundation–Lancet Commission on planetary health. Lancet. 2015;386(10007):1973–2028. 135. Haines A, McMichael AJ, Smith KR, et al. Public health benefits of strategies to reduce greenhouse-gas emissions: overview and implications for policy makers. Lancet. 2009;374(9707):2104–2114. 136. Ürge-Vorsatz D, Herrero ST, Dubash NK, Lecocq F. Measuring the co-benefits of climate change mitigation. Annu Rev Environ Res. 2014;39(1):549–582.

8 Environmental Change, Migration, Conflict, and Health Lauren Herzer Risi, Caroline Kihato, Rebecca Lorenzen, and Howard Frumkin

Environmental change can destabilize the settings in which people live and contribute to two of the most traumatic of human experiences: displacement and conflict. This chapter explores the ways in which environmental disruptions—from rapid-onset events such as hurricanes, tsunamis, landslides, and floods to slow-onset events such as drought, desertification, sea-level rise, erosion, and land degradation—affect migration, conflict, and health. Both migration and conflict are complex phenomena, with multiple causes. Environmental change is rarely the only factor driving either outcome. However, historical examples and modern tragedies make clear that environmental pressures can amplify demographic and economic stressors, poor governance and infrastructure, and other problems, resulting in dislocation, conflict, or both. Therefore, it is important that the environment be part of the conversation when addressing these global challenges. We begin with some historical and contemporary examples of environmental change and its effect on migration and conflict. We then discuss both migration and conflict, considering how our knowledge of these phenomena can help us anticipate them, reduce the harm they cause, and support resilience and recovery when they do occur.

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Environmental Change, Migration, and Conflict: Examples Past and Present A growing literature offers a rich variety of case studies that explore the links between environmental change (especially climate change), and migration, conflict, and health.1–3 Here we present half a dozen accounts, from ancient times to the present, that exemplify some of the complex issues involved.

The Ancestral Pueblo Peoples The ancestral Pueblo peoples (sometimes called Anasazi) inhabited a region near the Four Corners of the Southwestern United States beginning more than 3,000 years ago. For several centuries, starting about 700 ce, the population grew and the civilization thrived, thanks to regular rainfall that supported agriculture. Extensive settlements connected by hundreds of kilometers of roads featured stone structures up to five stories high. But the civilization collapsed after about 1200

ce,

amidst fierce violence and eventual aban-

donment of the settlements for parts unknown. Although there is disagreement among archaeologists regarding the causes, it is known that the region suffered a severe longterm drought at the end of the thirteenth century, and that extensive deforestation had occurred in the region.4 The resulting resource scarcity probably contributed to both conflict and eventual relocation. Similar forces are thought to have contributed to the downfall of Mayan civilization in the eleventh century.5

The Irish Potato Famine The Irish potato famine was one of the greatest disasters in Irish history. The ease with which potatoes grew in Irish soil and their high caloric value had made them a staple crop throughout the country by the late eighteenth century. In the early 1840s, a species of water mold known as Phytophthora infestans—the cause of potato blight—arrived in Europe, probably originating in Mexico. Ireland’s cold and moist environment in 1845 facilitated rapid spread of the blight, resulting in widespread potato crop failure.6 Several factors amplified the impact of the blight, including overreliance on a single crop and inhumane British government policies. The resulting Great Famine caused mass starvation, an estimated million deaths, and the emigration of an estimated 2 million people. The Irish population—8 million before the famine—has still not rebounded to previous levels.7

The Oklahoma Dust Bowl In the years leading up to the 1930s, mechanized farming exploded in the southern Great Plains region of the United States, spurred both by technological change (mass production of tractors) and by the rising price of wheat during World War I. Extensive tracts of

Environmental Change, Migration, Conflict, and Health  191

arid grassland were converted to cropland. Deep plowing of virgin topsoil dislodged the root systems of grasses that for millennia had stabilized the soil and trapped moisture. Common farming techniques of the era such as plowing fields before leaving them fallow, in the belief that this would allow rain to penetrate and remain in the soil more readily, instead desiccated farmland, allowing wind to sweep away fine dust.8 Massive dust storms darkened the skies, and vast amounts of topsoil were lost. When the Great Depression hit in 1929, farmers operating on narrow profit margins were pushed off their land, leaving behind dusty, untended plots that could not retain moisture or soil.9 Although dust storms and drought were longstanding characteristics of the Great Plains climatic zone,10 farming practices of the time, superimposed on economic trends, amplified typical droughts into an environmental crisis.11 Widespread financial ruin followed. An estimated 3.5 million people departed Oklahoma and other Great Plains states in the 1930s, one of the great internal migrations in U.S. history (Figure 8.1).

The Darfur Conflict Darfur is a region of mountains and arid plateau in western Sudan with a land area the size of Spain. Rainfall patterns are highly variable. Darfur’s population grew rapidly in the last part of the twentieth century and into the twenty-first, from 1.3 million in 1973 to 7.5 million in 2008. Ample rainfall until the 1960s gave way to progressively drier conditions and ultimately long-term drought beginning in the 1970s, a trend that was probably intensified by climate change.12,13 These changes occurred in the setting of longstanding

Figure 8.1 An iconic photograph of displaced people during the Dust Bowl era of the 1930s. Source: Dorothea Lange / Library of Congress

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competition for land between two populations in Darfur: mostly African settled farmers and mostly Arabic nomadic herders. War broke out in 2003 and raged on and off for more than a decade, causing an estimated 300,000 deaths,14 many from starvation. The conflict displaced more than 2 million people, some within Sudan and some to neighboring countries such as Chad, in one of the world’s worst humanitarian crises of the early twenty-first century (Figure 8.2). Darfur has been called “the first modern climate change conflict”15 and is an oft-cited example of environmental stressors contributing to conflict and population dislocation. The UN Environment Programme, for example, concluded that there was a “very strong link between land degradation, desertification and conflict” in Darfur.16 However, observers have cautioned against an overly deterministic view of climate–conflict links.17 Weather records reveal that rainfall in the years immediately preceding the conflict was above average and that the most severe drought had occurred 20–30 years before fighting began.18,19 Perhaps more importantly, many other factors, such as the dismantling of the traditional landholding system by the Khartoumbased government, played a major role. Accordingly, the simple attribution of the war to climate change has been criticized for absolving the Sudanese government of responsibility for the conflict. Although the drought contributed to the conflict, the causal pathways are complex and multifactorial.19–21

Figure 8.2 Some of the more than 2 million people who were displaced during the Darfur conflict. Large camps such as this one arose in Sudan and Chad, representing a complex humanitarian disaster. Source: Daniel Dickson (EC/ECHO), Creative Commons, license CC BY-SA 2.0

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Central American Migration Overall, illegal immigration to the United States declined in the decade before 2016, but during that period unauthorized immigration from Central America—mainly from the Northern Triangle countries of Guatemala, Honduras, and El Salvador—rose by 375,000.22 The most dramatic instance occurred in late 2018, when several thousand migrants from Central America set out for the United States. This “caravan” captivated international attention as some families and unaccompanied children walked as far as 2,500 miles to reach the U.S.–Mexico border. The commonly cited drivers of this migration included violence, drug cartels, poverty, and government instability, but the media largely overlooked the effects of two environmental drivers. First, an outbreak of coffee rust fungus (Hemileia vastatrix) that began in 2011 had destroyed crops throughout Latin America, especially in Central America.23 Warming temperatures allowed the fungus to extend its range and to flourish at higher altitudes than previously. Second, the 2015 El Niño triggered a severe drought, exacerbating agricultural losses. More than 1.7 million coffee workers lost their jobs, and financial losses reached an estimated $3.2 billion24—serious blows to economies that depend heavily on agriculture. These two events amplified underlying social and economic tensions, contributing to the pressure to migrate.

Chesapeake Bay The small but historically significant Tangier Islands off the coast of Virginia are already confronting the impacts of climate change. These low-lying islands, the last inhabited offshore islands in the Virginia portion of the Chesapeake Bay, were home to 727 people at the time of the 2010 census. Sea-level rise and coastal erosion have forced the abandonment of Uppards Island, one of the Tangier Islands.25 A 2015 U.S. Army Corps of Engineers study predicted that the main island may need to be abandoned as early as 2040.26 Historical examples from other Chesapeake Bay islands suggest that residents may abandon an island before it becomes physically uninhabitable, once the population falls below a critical mass needed to support community services and sustain hope.27 Local residents have thus far resisted the notion that climate change is responsible for the island’s loss of land area—a more than two-thirds reduction since 1850—and have insisted on seawall construction to protect the island.28,29 This predicament exemplifies the hard decisions ahead for endangered coastal communities whose residents do not want to leave.

Environmental Change, Migration, and Conflict: Core Concepts As these examples demonstrate, environmental change can be associated with population dislocation and armed conflict. Several distinctions are important.

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One distinction is between underlying precursors of migration or conflict, called primary factors, and triggering events, called secondary factors. Primary factors are longterm structural factors such as demographic shifts and economic growth patterns. These may not independently cause large-scale displacement or armed conflict, but they set the stage for other types of shocks to do so.30 Secondary factors are events that trigger migration or armed conflict. These include poor governance, poverty, inequality, unemployment, and political instability. Environmental change often falls into this category.31 A related distinction is between slow- and rapid-onset environmental drivers of migration and conflict. Rapid-onset drivers include natural and environmental disasters such as hurricanes, tsunamis, landslides, and floods. Slow-onset drivers, on the other hand, unfold over years; examples include drought, desertification, sea-level rise, erosion, and land degradation. Recent examples of sudden-onset disasters include hurricanes Katrina in 2005 and Maria in 2017. In New Orleans, Hurricane Katrina flooded approximately 75% of the city, displacing roughly 250,000 people—more than half the city’s population—and as many as 1 million people from the Gulf region.32 In Puerto Rico, Hurricane Maria devastated the island and destroyed much of its essential infrastructure. An estimated 3,000 excess deaths occurred across Puerto Rico,33 and nearly 400,000 people— well over 10% of the population—are thought to have left the island.34 In contrast, the migrations of ancestral Pueblo peoples and Central Americans exemplify slow-onset environmental drivers of migration, and the Darfur conflict exemplifies slow-onset conflict drivers.

Migration: Background Migration has long been a feature of human life. Researchers identify five sets of drivers that affect people’s decisions to move: economic, political, social, demographic, and environmental.31 Economic factors include poverty, income volatility, and wage differentials; all might induce people to relocate from an area of low economic opportunity to one with more opportunity. Political factors include poor or dysfunctional governance, instability, and conflict. Social factors include family and cultural norms such as the need to acquire funds for dowries, seek an education, or rejoin diaspora communities settled abroad. Demographic factors might include population growth that crowds out opportunity in a place of origin or an aging population in a receiving area that creates employment opportunities. Environmental factors include threats such as rising sea levels or severe storms and loss of ecosystem services such as drought or soil degradation; as discussed above, environmental drivers of migration may arise suddenly or gradually. Adding to the complexity is the fact that the drivers of migration interact with each other (Figure 8.3). For example, environmental degradation may lead to poverty, which in turn may drive migration. Given this complexity, disentangling the drivers of migration

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Figure 8.3 Drivers of migration. Environmental drivers interact with social, political, and economic factors to drive household decisions about migration. These forces interact in complex ways. Source: The Government Office for Science, London. Foresight: Migration and Global Environmental Change: Final Project Report. 2011. https://assets.publishing.service.gov.uk/government/uploads/ system/uploads/attachment_data/file/287717/11-1116-migration-and-global-environmentalchange.pdf

can be challenging, and scholars differ in their approaches. Demographers may focus on population structure, economists on poverty and income inequality, and geographers on environmental change. The number of international migrants globally grew from 173 million in 2000 to 220 million in 2010 and to 258 million in 2017. The largest source of international migrants per capita is Europe, followed by Latin America and the Caribbean, Africa, then Asia (Table 8.1 and Figure 8.4). Although in recent years there has been a spotlight on South-to-North migration (especially along the U.S.–Mexico border and in Europe), the majority of movement is South-to-South, much of it between countries in the same region. In Africa and Asia, 80% of all international migrants were born in their region of residence.35 Among immigrants in Europe, those originating in Europe exceed the combined number of those from Africa and Asia. Data do not support the perception in some wealthy countries of a mass migration from the Global South to the Global North.36

Migration and Environmental Change Throughout history, environmental pressures such as drought and soil depletion have played a role in human movement. Accounts in the Old Testament describe how, 4,000 years ago, prolonged drought and famine in Canaan drove Jacob and his sons to Egypt. As

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Table 8.1. International Emigration Sources and Immigration Destinations as a Percentage of Population, World Regions (2017) Emigrant Population (Leavers)

Region

Population (millions)

Population (millions)

Emigrants as % of Population

Immigrant Population (Arrivers) Population (millions)

Immigrants as % of Population

Africa

1,256

36

2.9%

25

2.0%

Asia

4,504

106

2.4%

80

1.8%

Europe

742

61

8.3%

78

10.5%

Latin America and Caribbean

646

38

5.8%

10

1.5%

North America

361

4

1.1%

58

16.0%

Oceania

41

2

4.6%

8

20.7%

n/a

11

n/a

n/a

n/a

7,550

258

3.4%

258

3.4%

Unknown World

Columns do not add to totals due to rounding. Source: UNDESA. International Migration Report 2017. New York, NY: United Nations Department of Economic and Social Affairs; 2017. https://www.un.org/en/development/desa/population /migration/publications/migrationreport/docs/MigrationReport2017_Highlights.pdf.

described above, drought, wind, and poor soil management in the 1930s Dust Bowl years led to the dislocation of 3.5 million Americans. In the Anthropocene, drought and sea-level rise are not the only potential drivers of migration; pollinator loss, severe storms, extreme heat, and soil loss, among other drivers, may provide additional pressures to relocate. Research suggests that low crop yields in Mexico drive migration to the United States,37 that weather anomalies drive rural to urban migration in sub-Saharan Africa,38 and that heat stress drives people to depart their villages in Pakistan39 and Indonesia.40 One recent assessment concluded that climate change is driving resettlement in Vietnam’s Mekong River delta, along the Limpopo River of Mozambique, on the Alaskan coast, in the Inner Mongolia Autonomous Region, and from the Carteret Islands to Bougainville Island in Papua New Guinea.40,41 But the environment is not working in isolation as a driver of migration and the role of other factors must be considered (see Figure 8.3). For example, the decision to relocate may be influenced by social networks in the receiving area, government policies toward migrants in the receiving area, and levels of aid available to adapt or rebuild locally.

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Figure 8.4 Numbers of international migrants classified by region of origin and destination, 2017. Northern America includes the United States and Canada, and Mexico is included in Latin America and the Caribbean. Source: United Nations Department of Economics and Social Affairs. International Migration Report 2017. ST/ESA/SER.A/403. New York, NY: UNDESA; 2017

Several patterns of migration in response to environmental drivers may be identified (Box 8.1 and Figure 8.5).42 At the bottom right of Figure 8.5 is labor migration—what might be called “ecological–economic migrants” who confront diminished livelihoods at home due to environmental changes and seek better opportunities elsewhere. This kind of migration often involves just one member of a household, is mostly temporary (either seasonal or long-term), and often features remittances sent back home. Moving to the left we see forced migration: people fleeing disasters or circumstances that are no longer viable. Such migrants generally move to the nearest place where life is bearable, often where aid is provided or where relatives live. They tend to remain anchored to their place of origin. Rapid-onset environmental changes in particular typically stimulate short-term, short-distance migration;43,44 those who move tend to return to their places of origin as soon as conditions permit.36 The next category, moving left, is displacement/resettlement, which consists of permanently displaced populations, such as people leaving coastal areas or small island nations that can no longer sustain their way of life. Finally, the bottom left box represents people without the ability or resources to depart—so-called trapped populations. At two points along the bottom of Figure 8.5 we see in situ adaptation, referring to those who are unable or unwilling to relocate and remain in place, doing their best to cope.

Box 8.1. A Glossary of Displacement Terms • Migrant: A person who has established a (semi-)permanent new residence in a place other than the place of habitual residence. • Forced (or involuntary) migrant: A person forced to leave home and seek refuge elsewhere. Causes may include natural or human-made environmental disasters, famine, development projects, and human trafficking and smuggling. • Irregular (also undocumented or unauthorized) migrant: A migrant whose current residence status does not conform with the immigration laws of the receiving country, regardless of mode of entry. • Internally displaced person: A person who has been forced to flee his or her place of habitual residence, in particular because of armed conflict, violence, human rights violations, or disasters, and who has not crossed a national boundary. • Refugee: A person forced to flee his or her country of nationality by a well-founded fear of persecution on the basis of race, religion, nationality, membership of a particular social group, or political opinion, and who has been granted refugee status by a receiving country. A legally recognized designation under the 1951 Geneva Refugee Convention. • Asylum seeker: A person who has applied to the immigration authorities of the receiving country for protection as a refugee and is awaiting a determination of status under the 1951 Geneva Refugee Convention. • Environmental migrant (or climate migrant): A person forced to leave his or her home region by sudden or long-term environmental degradation. The use of this term is debated when environmental degradation is a contributing but not major factor.a • Managed retreat: The planned relocation of communities and infrastructure away from at-risk areas (typically coastal areas) before they are severely affected by hazards such as sea-level rise.b • Platform on Disaster Displacement: A voluntary multigovernmental and civil society initiative to protect cross-border displaced people in the context of disasters and climate change. Launched in 2016 as a follow-up to an earlier effort, the Nansen Initiative. Adapted from Urquia ML, Gagnon AJ. Glossary: migration and health. J Epidemiol Community Health. 2011;65:467–472.

References a. Dun OV, Gemenne F. Defining “environmental migration.” FMR. 2008:10–11. b. Hino M, Field CB, Mach KJ. Managed retreat as a response to natural hazard risk. Nat Clim Change. 2017; 7(5):364.

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Figure 8.5 Migration patterns in response to global environmental change and associated drivers. Source: Adapted from Brzoska M, Fröhlich C. Climate change, migration and violent conflict: vulnerabilities, pathways and adaptation strategies. Migr Dev. 2016;5(2):190–210.

People are strongly anchored in their social networks.45 These social networks play a large role in the decision to migrate. Only where local social and cultural forces are positively disposed toward migration is it likely that people experiencing adverse effects from environmental change will begin to consider outmigration.46 Level of wealth is an important determinant of migration; people in poverty are less able to relocate than people with access to resources. Poverty increases vulnerability to acute and long-term environmental stressors and limits a community’s ability to adapt. But it also limits the ability to migrate in response to these changes, trapping some populations in place (Figure 8.6).47 For example, although farmers in Africa commonly migrate to look for work elsewhere in response to low soil quality, a study of Ugandan farmers showed the reverse—that migration declined with poor soil quality, because the affected families lacked the resources to send members off to seek work.48 Migrants often remain connected to their communities of origin. One link is financial remittances, which can help increase the resilience of source communities.49 Another link is social; the presence of a family member or friend in a destination can facilitate the migration of additional community members who need to relocate.2 Social resources, in the form of migrant networks between host and source communities, can also reinforce a family’s or community’s adaptive capacity. For example, a study of Dust Bowl migrants found that those with social networks that provided information about employment and housing opportunities fared better than those with few economic resources and few social

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Figure 8.6 Poverty and vulnerability to climate change: the phenomenon of “trapped populations.” Those with fewer resources (left side of the graph) face a double set of risks from environmental change: financial inability to move away from places at increasing environmental risk and high vulnerability to environmental change because of limited resources. These populations are likely to become trapped in places where they are vulnerable to environmental change. Source: The Government Office for Science, London. Foresight: Migration and Global Environmental Change—Final Project Report. 2011. https://assets.publishing.service.gov.uk/government/uploads /system/uploads/attachment_data/file/287717/11-1116-migration-and-global-environmental -change.pdf

networks. People in the latter category were more likely to end up in settlements of shacks in vulnerable areas along railways, highways, and rivers.50 Poverty may also limit people’s ability to return to their place of origin after forced migration. For example, when Hurricane Katrina hit New Orleans, many African Americans lived in lower-lying areas of the city. Facing two challenges—greater levels of damage to their homes and fewer resources with which to rebuild—many were unable to return to the city after the disaster.51

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Migration may be framed as a last resort—as a kind of failure—or more positively as an adaptive solution. In particular, planned and managed relocation can transition people from vulnerable situations to safer places.47,52,53 The deliberate relocation of populations is known as managed retreat (although this term is controversial because it may connote defeat; less tendentious equivalent terms include planned relocation and managed realignment).54 Small coastal populations and some island populations have implemented this process, but managed retreat is rarely—some would say too rarely—contemplated in the context of larger settlements such as coastal cities.55 Although migration can be a viable form of adaptation, it can also be maladaptive. This can happen in at least two ways. First, when economically active young people depart an environmentally pressured area—say, at a time of drought—their community may be left less resilient, with a deficit of skills and knowledge, and less capable of carrying out activities such as planting and harvesting.56 Second, a disturbing possibility is that as people migrate from rural to urban areas, driven at least in part by environmental pressures, they may relocate to areas of greater risk.57 As described in Chapter 13, many cities are highly vulnerable to such hazards as rising sea levels, severe weather events, and heat. Some researchers have attempted to predict the extent of migration that may come with ongoing global environmental change, especially climate change. For example, Hsiang and Sobel58 note that temperature gradients are small in tropical regions, so to escape rising temperatures, people would have to move large distances—an alteration of the more typical pattern of short-distance migration. They project that by the end of this century, 12.5% of the global population, mostly in tropical zones, would have to migrate more than 1,000 kilometers to maintain stable temperatures—meaning largescale migration to the edges of the tropics or beyond. A World Bank report projects that more than 143 million people across Sub-Saharan Africa, South Asia, and Latin America will be forced to move within their countries of origin by 2050, barring effective climate and development action.59 Of course, such predictions carry considerable uncertainty. For example, local adaptation could obviate much of this migration. These calculations highlight both the large potential impacts of planetary changes on migration in coming decades and the uncertainty surrounding such predictions.

Conflict In the more than seven decades since the end of World War II, the number of people killed in armed conflict and genocide has generally been in decline. Since the end of the Cold War, the number of conflicts has also declined.60,61 Yet violence across the globe remains disturbingly persistent, and instances of political conflict rose from 278 in 2006 to 402 in 2016.62 Twenty-first century conflicts are smaller, more intense, and protracted, and they tend to be concentrated in specific geographic areas, relative to wars of the past. Importantly, recent trends indicate a shift away from interstate wars, toward intrastate and nonstate conflicts (Figure 8.7).

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Figure 8.7 Number of armed conflicts, global, by type of conflict, 1946 to 2017. Note the decline of extrastate (between a state and a nonstate entity) and interstate (between two or more governments) conflicts and the rise of intrastate (civil wars) and internationalized (in which third states intervene) conflicts. Source: Dupuy Kendra, Rustad SA. Trends in armed conflict, 1946–2017. Conflict Trends 2018;5. Oslo: PRIO. Creative Commons, license CC-BY

Violent conflict is even more complex than suggested in Box 8.2 and Figure 8.7. It ranges from individual acts of interpersonal violence and crime, to social violence such as riots, communal conflicts, and violent mass demonstrations, to organized military activity.63 It is important to keep these distinctions in mind when considering the impact of environmental change on conflict.

Environmental Change and Conflict The concept of resource wars—the idea that states or nonstate actors fight over scarce resources—seems intuitive, and many historical conflicts have been attributed to such disputes, from numerous wars over water in the Middle East over millennia64 to Hitler’s 1941 invasion of the Soviet Union (seeking Azerbaijan’s oil). Water has been identified as a driver of wars in many places (such as in the Nile, Jordan, Tigris–Euphrates, and Indus systems), as have timber and minerals (the latter most notably in Africa and Southeast Asia). But as with migration, the causal links between resource scarcity and conflict are complex and multifactorial.65 As noted above, shortages of water and arable land may have contributed to the Darfur conflict, but so did underlying ethnic tensions and changes in that nation’s landholding system. Similarly, although severe drought, poor water

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Box 8.2. A Glossary of Conflict Terms • Armed conflict (also state-based conflict): A dispute between two parties, at least one of which is a government, over government or territory, involving the use of armed force, and resulting in at least twenty-five battlerelated deaths in one calendar year. • Communal conflict: Conflict between nonstate groups with shared religious or ethnic identity, but may also include intervillage clashes where narrower identities define the parties. • Extrastate conflict: Conflict between a state and a nonstate political entity, outside the borders of the state. • Inter-state conflict: A conflict between two or more governments using their armed forces. • Intrastate conflict (also civil war): A conflict between a government and a nongovernment party, with no interference from other countries. Fought within the borders of the state (although with the risk of spillover into bordering states). • Intrastate conflict with foreign involvement, or internationalized: A conflict between a government and a nongovernment party in which one or both sides receive active combat support from other governments. • Non-state conflict: The use of armed force between two organized armed groups, neither of which is a government, resulting in at least twenty-five battle-related deaths in a year. • Resource war: Violent interstate, intrastate, or nonstate conflict driven by competition for control over vital or valuable natural resources such as oil, water, land, timber, or minerals. It is understood that resource competition is not the only driver of these conflicts. • War: A state-based conflict resulting in at least 1,000 battle-related deaths in one calendar year. Adapted from Uppsala University Conflict Data Program, Institute for Policy Analysis of Conflict; and Klare MT, Levy B, Sidel V. The public health implications of resource wars. Am J Public Health. 2011;101(9):1615–1619.

management, and the resulting agricultural losses probably contributed to the devastating Syrian civil war beginning in 2011, sectarian divisions, ongoing revolutions in the region, and the policies of the Assad regime played central roles.13,66,67 A 2009 report by the UN Environment Programme concluded that “environmental factors are rarely, if ever, the sole cause of violent conflict.”68

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At the interpersonal scale, environmental factors seem to be linked to violence. Heat is a well-studied example. Laboratory studies suggest that heat triggers irritability and aggressiveness,69 and observational data suggest that crime and interpersonal violence rise with hot weather. Some of this evidence comes from time-series studies of disorderly conduct and violent crime in individual cities such as Cleveland, Baltimore, and Philadelphia,70–72 some comes from year-on-year comparisons across many cities,73 and some comes from comparisons of hot parts of the world with cooler parts.74 But this relationship is not consistently observed, and the association is not monotonic; crime may actually decrease at the very highest temperatures as people seek shelter from the heat.75 Moreover, other factors such as social circumstances, poverty, and law enforcement probably play a greater role than temperature in shaping level of interpersonal crime and violence.76,77 But interpersonal violence is a quite different phenomenon than large-scale organized violence. Could armed conflict be linked to environmental factors? In particular, in the setting of far-reaching global environmental change, with potential scarcity of such resources as water, phosphates, cropland, and timber, could the threat of conflict over natural resources rise? Under certain circumstances, environmental factors may increase the risk of violent conflict. Countries whose economies depend on the export of primary goods, for example, may be particularly vulnerable to conflict when the availability of those goods is compromised or unequally distributed. Furthermore, once conflict has erupted, the existence of highly valuable extractive resources may prolong violence as they are exploited by opposing groups. Resources such as diamonds, cocoa, timber, and minerals have been used by armed groups in Sierra Leone, Liberia, Angola, and Cambodia to finance their activities. Valuable resources such as these “may also alter the dynamics of conflict itself by encouraging combatants to direct their activities towards securing the assets that enable them to continue to fight.”68 Some research has suggested associations between weather anomalies—wet or dry years or hot years—and civil wars.78–81 One analysis of more than 6,000 instances of social conflict in Africa over 20 years, using the Social Conflict in Africa Database, considered a broad range of conflict types including riots, antigovernment violence, organized rebellion, and armed conflict. It found that rainfall variability has a significant effect on both large- and small-scale instances of political conflict.80 Such observations are not confined to Africa; rain shocks have been linked to conflicts as diverse as religious violence in India82 and land invasions in Brazil.83 However, other research findings are more equivocal; the links between weather anomalies and conflict are not consistently found.84,85 Based on observations such as these, the discussion of global environmental change has been “securitized” in recent years—framed as a matter of national security.86 One conceptual approach, the neo-Malthusian, holds that resource scarcity deepens grievances

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and competition, fueling conflict. Another approach, focusing on opportunity cost, holds that people are more likely to make the decision to participate in violence when scarcity prevails, economic alternatives are few, and they have less to lose.63 Based on such theories, some have predicted that planetary change will bring increasing conflict.61,87 Although the empirical evidence to support such projections is mixed, several conclusions are clear.88 First, resource scarcity is rarely, if ever, the sole cause of conflict. Concurrent factors that play a role include population growth (which increases competition for resources); poverty or income inequality; a sense of hopelessness and of limited options; government inability to buffer shortages due to limited revenues, corruption, or other factors; and underlying political or ethnic tensions.89,90 Prosperity, effective government, and institutions that can peacefully manage conflict are protective against intergroup violence.88 Certain conditions must be met for conflict to break out: People with grievances must be part of an ethnic, religious, or class-based grouping capable of violent action, and the political structure must impede the peaceful expression of grievances.91,92 Second, the risk of conflict related to resource scarcity is highest in resource-dependent settings such as pastoral societies in Africa, where people have few buffers against shortages of water, food, and land.93 Communities that are subject to environmental disruption, through either external or internal processes, are likely to become poorer as a consequence. This poverty reduces their ability to respond to a range of threats, including conflict, ecological disasters, disease, and economic hardship. Third, environmental pressures are more likely to lead to nonstate than interstate conflicts. In fact, most experts agree that the risk of interstate war due to resource scarcity is low.88 Fourth, even if the evidence directly linking environmental scarcity and conflict is mixed, environmental scarcity or disasters can clearly cause economic slowdowns or shocks, undermine institutions that deliver public goods, and cause political instability that weakens states, thereby exacerbating conditions that raise the risk of conflict.94 This sequence, with environmental pressures leading to political instability, was part of the genesis of the Darfur conflict, the 2012 Tuareg revolt in Mali following desertification of traditional grasslands, and the Syrian civil war that began in 2011 after a devastating 5-year drought. Fifth, although resource scarcity can be associated with conflict, the reverse pattern can also be seen: In some circumstances, ample resources enable conflict, and scarcity is met with solidarity. Mounting large-scale military operations can be difficult in the face of environmental scarcity; fewer resources are available to militants, arid environments may be more difficult to fight in than well-watered ones, and people whose basic needs are not met may be less able or willing to participate in violence.63 For example, Genghis

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Khan’s empire is thought to have expanded only when a rainy period boosted grassland productivity in Mongolia, enabling him to raise and provision an army.95 Under the right conditions, scarcity and environmental degradation may actually lead to greater cooperation.96 Water scarcity has been extensively studied, and the circumstances that predict cooperation (or conflict) are well described. A study of the world’s 276 transboundary water basins found that international cooperation regarding water is more common than conflict, with the likelihood of conflict greatly dependent on institutional capacity to absorb rapid changes.97,98 A study of water-related conflict and cooperation in thirty-five Mediterranean, Middle Eastern, and Sahel countries during the period 1997–2009 found violent water conflicts to be extremely rare; other mediating factors, such as population pressure, agricultural productivity, political stability, and economic development, had a strong effect on water conflict risk.99 Three additional factors are associated with the prospect of cooperation in the face of water scarcity: timing, severity, and spatial scale. With regard to timing, an analysis of 50 years of water conflicts found that short-term water scarcity is associated with increased interstate cooperation, whereas long-term variability in precipitation is associated with a higher incidence of conflict.100 With regard to severity, perhaps surprisingly, severe scarcity is more likely to lead to cooperation than is moderate scarcity.101,102 Finally, with regard to spatial scale, water scarcity over large territories is less likely to devolve into conflict than are disputes at the local or subnational level or between sectors.101,102

Links between Migration and Conflict Does Migration Cause Conflict? In general, the evidence does not support a strong link between migration and violent conflict.2,42 There are exceptions, however. Migration from El Salvador to Honduras in the 1960s resulted in pressure on Honduran land, contributing to the 1969 “Soccer War” between those two nations, and internal and cross-border Bangladeshi migration in the 1980s, driven by environmental degradation, contributed both to violence in receiving areas in India and to an internal insurgency in Bangladesh.1 The risk of violence may increase when resources are scarce in the receiving area, there is preexisting conflict in the receiving area, or there is ethnic tension between migrants and those in the receiving area.1,42 In fact, in some cases migration may reduce the potential for conflict. It can act as an escape valve, reducing competition for resources in places from which people migrate, and boosting adaptive capacity through remittances. For example, remittances sent home by migrants from Mali, Mauritania, and Senegal help support local economies and increase resilience to environmental change.49

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Does Conflict Cause Migration? Evidence is stronger for the reverse process: conflict as a cause of migration. Different forms of violence differ in their propensity to trigger migration, with civil wars the highest, followed by genocide. Smaller conflicts such as communal violence are far less likely to trigger large-scale migration.93 In fact, according to the UN High Commissioner on Refugees, more than half of the world’s refugee population as of mid-2018 derived from just three war-torn countries: Afghanistan, South Sudan, and Syria.103 Case studies from conflict settings such as Somalia104 and Mozambique105 exemplify the role of “migratory coping” as a response to violence, albeit with important context-specific features. Of note, even in the setting of severe conflict, most people do not depart; migration rates tend to be unexpectedly low. Factors such as poverty (inability to afford to travel) and unpredictable violence (that may block exit routes) can incline people toward remaining in place.93 Conflict is not the only driver of such migration; according to the World Food Programme, when violence is accompanied by food insecurity, there is a substantially higher pressure to migrate.106

The Health Implications of Migration and Conflict Migration and conflict—two of the most disruptive and traumatic experiences people can endure—threaten health in many ways.

Health Implications of Conflict Armed conflict destabilizes wellbeing in ways that extend well beyond conventional notions of health. In the words of one set of experts, War has enormous tragic impacts on people’s lives and the environment. War accounts for more death and disability than many major diseases do. It destroys families, communities, and sometimes entire nations and cultures. It siphons human and financial resources away from health and other human services. It damages the infrastructure that supports the health of society, such as systems that provide safe food and water, electrical power, transportation, and communication. War violates human rights. It uproots people, forcing them to migrate to other countries or to become internally displaced persons within their own countries. It contributes to the spread of infectious disease. The mindset of war––which endorses the notion that violence is the best way to resolve conflicts or disputes––contributes to domestic violence, street crime, and many other kinds of violence throughout the world. War, and the preparation for war, contaminates and damages the environment and uses vast amounts of nonrenewable fuels and other resources. In sum, war damages not only the health of people but also the very fabric of society.61

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The far-reaching health consequences of armed conflict are beyond the scope of this chapter; they are discussed by Taipale107 and in Levy and Sidel.108 Most obviously, armed conflict inflicts injuries and death on combatants. It also kills and wounds civilians, both through the violence of fighting and through indirect pathways such as disease, hunger, and sexual violence. The full mortality burden can be difficult to quantify; estimates of total mortality in the Iraq War (2003–2006) range from roughly 100,000 to 1 million,109 with the accurate figure probably around 500,000.110 Although the proportion of conflictrelated deaths suffered by civilians is debated (and depends heavily on the individual conflict and on methods of counting), it is probably higher in modern wars than in wars of the past and may range from 50% to 90%.111 Much of the civilian burden is not due to combat; for example, with the onset of the 1991 Gulf War, infant and child mortality in Iraq rose threefold, including a sixfold increase in diarrhea mortality,112 accounting for an estimated 400,000 to 500,000 excess deaths among children before the decade ended.113 Nor do the health impacts of conflict end with the cessation of hostilities. Excess mortality and morbidity can persist, through a variety of pathways, from residual landmines to posttraumatic stress and traumatic brain injury among both combatants and civilians. The destruction of health facilities and of infrastructure essential to health, such as water and sewage systems, agriculture, and schools, can take many years to remedy.

Health Implications of Migration Migrants in general may have a health advantage over people who do not migrate, reflecting a selection process.114 But people who are displaced by hardship confront many threats to their health and well-being,115 a pattern that is clearly evident among people displaced by acute or long-term environmental disruption.116,117 Among the most important categories of health threats are infectious diseases, nutritional status, mental health, and noncommunicable diseases. Women and children are a particular risk group (Box 8.3). Infectious diseases are a concern for many reasons.118 When environmental disasters dislocate people suddenly, and when they end up in precarious situations such as refugee camps or urban areas unprepared to receive them, access to fresh water, clean food, and sanitary facilities may be compromised, promoting the spread of water- and food-borne diseases (e.g., cholera, dysentery, typhoid fever, and hepatitis A and E). Crowding promotes the spread of measles, meningitis, and acute respiratory infection and of vectorborne disease (including malaria and dengue). When people encounter unaccustomed disease risks in areas to which they flee, as when relocating from areas of low to high malaria endemicity, they may be immunologically unprepared and especially vulnerable.

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Box 8.3. Women’s and Children’s Health in Refugee Camps Sarah Barnes Conflict and dislocation threaten health in many ways. Displaced women and girls are particularly vulnerable, and they regularly confront a lack of access to essential reproductive health services (RHSs). Women and children often represent a majority of displaced people. For example, of the more than 1 million South Sudanese people who fled to Uganda in 2016 and 2017, more than 85% were women and children.a Women in such circumstances have multiple vulnerabilities, which may include the psychological and physical sequelae of forced relocation, conflict violence, and sexual violence; lack of access to medical care; exposure to infectious diseases including HIV/AIDS; nutritional deficiencies; lack of education; and lack of access to information about contraception and other reproductive health measures.b,c In some cultural contexts, displaced women confront additional challenges including patriarchal power relationships and disempowerment, pressure to marry early and have many children, disinclination to have Caesarean sections even when medically indicated, and female genital mutilation.d–f In 2014, for example, Save the Children reported that early and forced marriage among Syrian refugee girls in Jordan had doubled in the 3 years since the onset of the Syrian war.g The health consequences of these vulnerabilities are evident in studies of refugee camps, which often reveal high birth rates (including high rates of unplanned pregnancies); high rates of sexually transmitted diseases, pregnancy complications, maternal mortality, and underweight and stunting among children; and high rates of depression.b,c,h,i Essential RHSs include family planning services, regular antenatal care, expert labor and delivery services, postnatal care for mother and child, education and counseling throughout, and associated mental health and general medical care as needed. These services must be undergirded by training of providers, robust supply chain management, and community outreach to influence attitudes and norms regarding reproductive health.j Strong evidence supports the efficacy of an integrated approach in protecting maternal and child health.k Starting in the mid-1990s, global attention focused on deficiencies in RHSs for women affected by conflict and displacement. In 1995, UN agencies, humanitarian organizations, academic institutions, and donors formed the Inter-agency Working Group on Reproductive Health in Crises (IAWG; see iawg.net).l,m IAWG provides guidance for

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RHSs in settings of conflict and natural disaster, including a Minimum Initial Service Package (MISP) of essential actions to: • Designate a responsible organization to lead reproductive health service delivery • Prevent and manage the consequences of sexual violence • Reduce HIV transmission • Prevent maternal and newborn death and illness • Plan for comprehensive sexual and reproductive health care, ideally integrated into primary health care The delivery of RHSs in refugee camps has improved over time, in part thanks to these guidelines. In fact, some studies find that access to care, and health indicators such as maternal mortality, are better in refugee camps than in the host countries in which they are situated.n-p However, shortcomings in RHSs in refugee camps persist, and many camps that have been studied do not fully meet MISP standards.q,r Barriers include shortages of funds and of skilled providers, delays in seeking care, and, perhaps most pervasively, ideological, managerial, and policy barriers and perverse donor influence.s,t RHSs for people in refugee camps remain an ongoing challenge. References a. Robinson C. South Sudanese refugees in Uganda now exceed 1 million. United Nations High Commissioner for Refugees (UNHCR). 2017 https://www.unhcr.org /news/stories/2017/8/59915f604/south-sudanese-refugees-uganda-exceed-1-million. html. Accessed April 2020. b. Austin J, Guy S, Lee-Jones L, McGinn T, Schlecht J. Reproductive health: a right for refugees and internally displaced persons. Reprod Health Matters. 2008;16(31):10– 21. c. Balinska MA, Nesbitt R, Ghantous Z, Ciglenecki I, Staderini N. Reproductive health in humanitarian settings in Lebanon and Iraq: results from four cross-sectional studies, 2014–2015. Confl Health. 2019;13:24. d. Hattar-Pollara M. Barriers to education of Syrian refugee girls in Jordan: gender-based threats and challenges. J Nursing Scholarship. 2019;51(3):241–251. e. Parmar PK, Jin RO, Walsh M, Scott J. Mortality in Rohingya refugee camps in Bangladesh: historical, social, and political context. Sex Reprod Health Matters. 2019;27(2):1610275. f. Gee S, Vargas J, Foster AM. “The more children you have, the more praise you get from the community”: exploring the role of sociocultural context and perceptions of care on maternal and newborn health among Somali refugees in UNHCR supported camps in Kenya. Confl Health. 2019;13:11–11. g. Save the Children. Too Young to Wed: The Growing Problem of Child Marriage among Syrian Girls in Jordan. London: Save the Children; 2014.

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h. Hashmi AH, Nyein PB, Pilaseng K, et al. Feeding practices and risk factors for chronic infant undernutrition among refugees and migrants along the Thailand–Myanmar border: a mixed-methods study. BMC Public Health. 2019;19(1):1586. i. Falb KL, McCormick MC, Hemenway D, Anfinson K, Silverman JG. Symptoms associated with pregnancy complications along the Thai–Burma border: the role of conflict violence and intimate partner violence. Maternal Child Health J. 2014;18(1):29–37. j. Curry DW, Rattan J, Nzau JJ, Giri K. Delivering high-quality family planning services in crisis-affected settings I: program implementation. Global Health Sci Pract. 2015;3(1):14–24. k. Singh NS, Smith J, Aryasinghe S, Khosla R, Say L, Blanchet K. Evaluating the effectiveness of sexual and reproductive health services during humanitarian crises: A systematic review. PLoS One. 2018;13(7):e0199300. l. McGinn T, Austin J, Anfinson K, et al. Family planning in conflict: results of crosssectional baseline surveys in three African countries. Confl Health. 2011;5(1):11. m. Girard F, Waldman W. Ensuring the reproductive rights of refugees and internally displaced persons: legal and policy issues. Int Family Planning Perspect. 2000;26(4):167– 173. n. Morgan SA, Ali MM. A review of methodology and tools for measuring maternal mortality in humanitarian settings. Health Policy Plan. 2018;33(10):1107–1117. o. Tran NT, Dawson A, Meyers J, Krause S, Hickling C. Developing institutional capacity for reproductive health in humanitarian settings: a descriptive study. PLoS One. 2015;10(9):e0137412. p. Pierce H. Reproductive health care utilization among refugees in Jordan: provisional support and domestic violence. Womens Health (Lond). 2019;15:1745506519861224. q. Whitmill J, Blanton C, Doraiswamy S, et al. Retrospective analysis of reproductive health indicators in the United Nations High Commissioner for Refugees post-emergency camps 2007–2013. Confl Health. 2016;10:3. r. Krause S, Williams H, Onyango MA, et al. Reproductive health services for Syrian refugees in Zaatri Camp and Irbid City, Hashemite Kingdom of Jordan: an evaluation of the Minimum Initial Services Package. Confl Health. 2015;9(suppl 1):S4. s. Hynes M, Sakani O, Spiegel P, Cornier N. A study of refugee maternal mortality in 10 countries, 2008–2010. Int Perspect Sex Reprod Health. 2012;38(4):205–213. t. Hakamies N, Geissler PW, Borchert M. Providing reproductive health care to internally displaced persons: barriers experienced by humanitarian agencies. Reprod Health Matt. 2008;16(31):33–43.

Sexual violence—a tragic correlate of population displacement—promotes the spread of sexually transmitted diseases. The interruption of health services, in particular vaccination programs, increases the risk of such diseases as measles. Nutrition may be compromised in the setting of migration. Although migration may be triggered by food shortages in the place of origin, people may arrive in places where they have few economic opportunities and where aid programs do not provide adequate

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food.116 On the other hand, migration can help blunt nutritional deficiencies through remittances. During the 2008 food crisis in El Salvador, children in households with access to remittances had smaller declines in their height-for-age than children in households without such access.119 Mental health problems are a major concern among migrants—some due to predisplacement trauma and some to a complex of stressors encountered during and after migration. These stressors may include “fragmented social networks and separation from family, loss of familiar social contexts, poor social connections, diminished sense of belonging, economic deprivation, inadequate housing, little educational and job security, and in some cases mandatory detention.”116 When the displacement is acute, as after a disaster, many of these stressors are heightened.120 Depression, anxiety, substance abuse, and psychosomatic illnesses are common in postdisaster settings (see Chapter 9). When people are unwelcome in receiving areas, confronting social exclusion, discrimination, and perhaps legal challenges, mental health problems may be intensified.121 Noncommunicable diseases are increasingly common worldwide, and migrants carry this burden with them during relocation. One challenge is the breakdown of effective prevention, screening, and continuity of care associated with dislocation. Once established in new settings, migrants may face additional challenges, including poor access to health services (compounded by low health literacy and language barriers), limited earning potential, and unhealthy physical activity and dietary patterns. In a Danish study, migrants from Africa, Asia, and the Middle East suffered a diabetes incidence 2.5 times higher than that of native-born Danes.122

Solutions While conflict and relocation are both responses to environmental change, they differ in a fundamental way: Violence is never desirable, but relocation may be a sensible adaptive response. Solutions therefore fall into several categories. In the context of planetary health, primary prevention is essential. Decarbonizing the global economy, reducing the loss of arable land and soil, stewarding freshwater resources, and other such efforts (described more fully in Chapters 4, 5, and 12) have a wide range of benefits. Among them are reduced pressures driving conflict and migration. Prevention of armed conflict is a far-reaching goal whose full exploration is beyond the scope of this chapter. Key elements include effective, accountable governance; fair distribution of resources; provision of human services including health care and education; reduction of military budgets; and countering of cultural norms that permit or facilitate violence.123 Peaceful conflict resolution has been a goal throughout history; with the steep reduction in global violence over the last century, there is reason to hope for continued success despite the emerging challenges of planetary change.

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Adaptation to global environmental change is part of preventing migration. Adaptation can reduce vulnerability to both sudden shocks and long-term trends. Examples include switching farming practices to drought-tolerant crops and soil-conserving techniques, not building in floodplains, constructing levees and sea walls, restoring coastal barrier systems (mangroves, vegetated dunes, coral reefs, wetlands), and altering building codes to put key utilities on roofs instead of in basements.124,125 When sudden environmental disasters displace populations, health protection includes provision of shelter, food, water, sanitation, and medical care (including mental health care); public health services such as diarrheal disease control, measles immunization, and maternal and child health care; and protection from violence. Keeping communities intact in receiving areas is helpful. Prompt, organized restoration of infrastructure in disaster-affected areas and facilitated return, within the limits of available resources, is an important goal. If migration is to be long-term instead of temporary, provisions for safe, healthy, and equitable resettlement are essential. This is an enormous challenge for governance and for institutional structures;126,127 European and North American politics were upended in recent years by the perception (if not the reality) of migrant “invasions.” Innovative approaches to human rights, legal structures that manage migration, perhaps including new definitions of refugee status under international law, and institutional responses that resettle and integrate migrants into their new settings, will be essential.128

Authors Lauren Herzer Risi is project director of the Wilson Center’s Environmental Change & Security Program in Washington, DC, where she strives to connect research, policy, and practice to inform innovative and integrated solutions to one of today’s most pressing challenges: the connection between environmental change and security. Caroline Wanjiko Kihato is a visiting associate professor in the Graduate School of Architecture at the University of Johannesburg and a global fellow with the Wilson Center’s Global Risk and Resilience Program. Rebecca Lorenzen, MPP grew up in Mexico City and worked with the Mexican federal government for nearly a decade before returning to school to earn a master’s degree in public policy from Georgetown University. Howard Frumkin, MD, DrPH is professor emeritus of environmental and occupational health sciences, and former dean, at the University of Washington School of Public Health. Sarah B. Barnes is project director of the Maternal Health Initiative and women and gender advisor at the Woodrow Wilson International Center for Scholars.

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Flitter E. Residents of Tangier Island reject “climate” victim label. Reuters/The Wider Image. 2017. https://widerimage.reuters.com/story/residents-of-tangier-island-reject-climate -victim-label.

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31. Black R, Adger WN, Arnell NW, Dercon S, Geddes A, Thomas D. The effect of environmental change on human migration. Glob Environ Change. 2011;21:S3–S11. 32. Bliss L. 10 years later, there’s so much we don’t know about where Katrina survivors ended up. CityLab. 2015. https://www.citylab.com/equity/2015/08/10-years-later -theres-still-a-lot-we-dont-know-about-where-katrina-survivors-ended-up/401216/. Accessed April 2020. 33. Santos-Burgoa C, Sandberg J, Suárez E, et al. Differential and persistent risk of excess mortality from Hurricane Maria in Puerto Rico: a time-series analysis. Lancet Planet Health. 2018;2(11):e478–e488. 34. Echenique M, L. M. Mapping Puerto Rico’s hurricane migration with mobile phone data. CityLab. 2018. https://www.citylab.com/environment/2018/05/watch-puerto -ricos-hurricane-migration-via-mobile-phone-data/559889/. Accessed April 2020. 35. UNDESA. International Migration Report 2017. New York, NY: United Nations Department of Economic and Social Affairs; 2017. 36. Findlay AM. Migrant destinations in an era of environmental change. Glob Environ Change. 2011;21:S50–S58.

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37. Feng S, Krueger AB, Oppenheimer M. Linkages among climate change, crop yields and Mexico–US cross-border migration. Proc Natl Acad Sci. 2010;107(32):14257–14262. 38. Marchiori L, Maystadt J-F, Schumacher I. The impact of weather anomalies on migration in sub-Saharan Africa. J Environ Econ Manag. 2012;63(3):355–374. 39. Mueller V, Gray C, Kosec K. Heat stress increases long-term human migration in rural Pakistan. Nat Clim Change. 2014;4(3):182–185. 40. Bohra-Mishra P, Oppenheimer M, Hsiang SM. Nonlinear permanent migration response to climatic variations but minimal response to disasters. Proc Natl Acad Sci. 2014;111(27):9780–9785. 41. de Sherbinin A, Castro M, Gemenne F, et al. Preparing for resettlement associated with climate change. Science. 2011;334(6055):456–457. 42. Brzoska M, Fröhlich C. Climate change, migration and violent conflict: vulnerabilities, pathways and adaptation strategies. Migr Dev. 2015;5(2):190–210. 43.

Renaud FG, Bogardi JJ, Dun O, Warner K. Control, Adapt or Flee: How to Face Environmental Migration? Bonn, Germany: United Nations University Institute for Environment and Human Security; 2007.

44. Kniveton D, Schmidt-Verkerk K, Smith C, Black R. Climate change and migration. In: IOM Migration Research Series. Geneva, Switzerland: UN Migration; 2008. 45. Warner K, Erhart C, de Sherbinin A, Adamo SB, Chai-Onn TC. In Search of Shelter: Mapping the Effects of Climate Change on Human Migration and Displacement. A policy paper prepared for the 2009 Climate Negotiations. Bonn, Germany: United Nations University, CARE, CIESN Columbia University; 2009. 46. Piguet E, Pécoud A, de Guchteneire P, eds. Migration and Climate Change. Cambridge, UK: Cambridge University Press; 2011. 47. Black R, Bennett SRG, Thomas SM, Beddington JR. Migration as adaptation. Nature. 2011;478(7370):447–449. 48.

Gray CL. Soil quality and human migration in Kenya and Uganda. Glob Environ Change. 2011;21(2):421–430.

49. Scheffran J, Marmer E, Sow P. Migration as a contribution to resilience and innovation in climate adaptation: social networks and co-development in Northwest Africa. Appl Geogr. 2012;33:119–127. 50. McLeman R, Smit B. Migration as an adaptation to climate change. Clim Change. 2006;76(1):31–53. 51. Fussell E, Sastry N, VanLandingham M. Race, socioeconomic status, and return migration to New Orleans after Hurricane Katrina. Popul Environ. 2009;31(1–3):20–42. 52. Naik A. Migration and natural disasters. In: Laczko FCA, ed. Migration, Environment and Climate Change: Assessing the Evidence. Geneva, Switzerland: International Organization for Migration; 2009:245–317. 53. Government Office for Science. Foresight: Migration and Global Environmental Change: Future Challenges and Opportunities. London, UK: Government Office for Science; 2011. 54. Dannenberg AL, Frumkin H, Hess JJ, Ebi KL. Managed retreat as a strategy for climate change adaptation in small communities: public health implications. Clim Change. 2019;153(1–2):1–14. 55. Koslov L. The case for retreat. Public Cult. 2016;28(2 79):359–387.

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56. Jacobson C, Crevello S, Chea C, Jarihani B. When is migration a maladaptive response to climate change? Reg Environ Change. 2018;19(1):101–112. 57. Geddes A, Adger WN, Arnell NW, Black R, Thomas DSG. Migration, environmental change, and the challenges of governance. Environ Plann C. 2012;30(6):951– 967. 58. Hsiang SM, Sobel AHJ Sr. Potentially extreme population displacement and concentration in the tropics under non-extreme warming. Sci Rep. 2016;6:25697. 59. Rigaud KK, de Sherbinin A, Jones B, et al. Groundswell. Washington, DC: World Bank; 2018. 60. Dupuy K, SA R. Trends in Armed Conflict, 1946–2017. Oslo, Norway: Peace Research Institute Oslo; 2018. 61. Klare MT, Levy BS, Sidel VW. The public health implications of resource wars. Am J Public Health. 2011;101(9):1615–1619. 62. United Nations Office for the Coordination of Humanitarian Affairs. World Humanitarian Data and Trends 2018. 2018. http://interactive.unocha.org/publication/datatrends 2018/. 63. Salehyan I, Hendrix CS. Climate shocks and political violence. Glob Environ Change. 2014;28:239–250. 64. Gleick PH. Water, war & peace in the Middle East. Environ Sci Policy Sustainable Dev. 1994;36(3):6–42. 65. Koubi V. Climate change and conflict. Annu Rev Political Sci. 2019;22(1):343–360. 66. Gleick PH. Water, drought, climate change, and conflict in Syria. WCAS. 2014;6(3):331–340. 67. Selby J, Dahi OS, Fršöhlich C, Hulme M. Climate change and the Syrian civil war revisited. Political Geogr. 2017;60:232–244. 68. UNEP. From Conflict to Peacebuilding: The Role of Natural Resources and the Environment. Nairobi, Kenya: United Nations Environment Programme; 2009. 69. Anderson CA. Temperature and aggression: ubiquitous effects of heat on occurrence of human violence. Psychol Bull. 1989;106(1):74–96. 70. Butke P, Sheridan SC. An analysis of the relationship between weather and aggressive crime in Cleveland, Ohio. WCAS. 2010;2(2):127–139. 71. Michel SJ, Wang H, Selvarajah S, et al. Investigating the relationship between weather and violence in Baltimore, Maryland, USA. Injury. 2016;47(1):272–276. 72. Schinasi LH, Hamra GB. A time series analysis of associations between daily temperature and crime events in Philadelphia, Pennsylvania. J Urban Health. 2017;94(6):892– 900. 73. Anderson CA, Bushman BJ, Groom RW. Hot years and serious and deadly assault: empirical tests of the heat hypothesis. J Pers Soc Psychol. 1997;73(6):1213–1223. 74. Van Lange PAM, Rinderu MI, Bushman BJ. Aggression and violence around the world: A model of Climate, Aggression, and Self-control in Humans (CLASH). Behav Brain Sci. 2016;40. 75. Gamble JL, Hess J. Temperature and violent crime in Dallas, Texas: relationships and implications of climate change. West J Emerg Med. 2012;13(3):239–246.

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76. O’Loughlin J, Linke AM, Witmer FDW. Effects of temperature and precipitation variability on the risk of violence in sub-Saharan Africa, 1980–2012. Proc Natl Acad Sci. 2014;111(47):16712–16717. 77.

Raleigh C, Linke A, O’Loughlin J. Extreme temperatures and violence. Nat Clim Change. 2014;4(2):76–77.

78. Burke MB, Miguel E, Satyanath S, Dykema JA, Lobell DB. Warming increases the risk of civil war in Africa. Proc Natl Acad Sci. 2009;106(49):20670–20674. 79. Burke M, Hsiang SM, Miguel E. Climate and CONFLICT. Annu Rev Econ. 2015;7(1):577–617. 80. Hendrix CS, Salehyan I. Climate change, rainfall, and social conflict in Africa. J Peace Res. 2012;49(1):35–50. 81. Miguel E, Satyanath S, Sergenti E. Economic Shocks and civil conflict: an instrumental variables approach. J Political Econ. 2004;112(4):725–753. 82. Sarsons H. Rainfall and conflict: a cautionary tale. J Dev Econ. 2015;115:62–72. 83. Hidalgo FD, Naidu S, Nichter S, Richardson N. Economic determinants of land invasions. Rev Econ Stat. 2010;92(3):505–523. 84. Theisen OM, Gleditsch NP, Buhaug H. Is climate change a driver of armed conflict? Clim Change. 2013;117(3):613–625. 85. Buhaug H, Nordkvelle J, Bernauer T, et al. One effect to rule them all? A comment on climate and conflict. Clim Change. 2014;127(3–4):391–397. 86. Levy MA. Is the environment a national security issue? Int Secur. 1995;20(2):35–62. 87.

Welzer H. Climate Wars: What People Will Be Killed For in the 21st Century. Hoboken, NJ: Wiley; 2015.

88. Adger W, Pulhin JM, Barnett J, et al.. Human security. In: Field CB, Barros VR, Dokken DJ, et al., eds. Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK: Cambridge University Press; 2014:755–791. 89. Raleigh C, Urdal H. Climate change, environmental degradation and armed conflict. Political Geogr. 2007;26(6):674–694. 90. Barnett J, Adger WN. Climate change, human security and violent conflict. Political Geogr. 2007;26(6):639–655. 91. Homer-Dixon TF. Environmental scarcities and violent conflict: evidence from cases. Int Secur. 1994;19(1):5–40. 92. Urdal H. People vs. Malthus: Population pressure, environmental degradation, and armed conflict revisited. J Peace Res. 2005;42(4):417–434. 93. Raleigh C. The search for safety: the effects of conflict, poverty and ecological influences on migration in the developing world. Glob Environ Change. 2011;21:S82–S93. 94. Scheffran J, Brzoska M, Kominek J, Link PM, Schilling J. Disentangling the climate– conflict nexus: empirical and theoretical assessment of vulnerabilities and pathways. Rev Eur Stud. 2012;4(5). 95. Pederson N, Hessl AE, Baatarbileg N, Anchukaitis KJ, Di Cosmo N. Pluvials, droughts, the Mongol Empire, and modern Mongolia. Proc Natl Acad Sci. 2014;111(12):4375– 4379.

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96. Dinar S. Resource scarcity and environmental degradation: implications for the development of international cooperation. In. Beyond Resource Wars. Cambridge, MA: The MIT Press; 2011:289–306. 97. Wolf AT, Yoffe SB, Giordano M. International waters: identifying basins at risk. Water Policy. 2003;5(1):29–60. 98.

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99. Bšöhmelt T, Bernauer T, Buhaug H, Gleditsch NP, Tribaldos T, Wischnath G. Demand, supply, and restraint: determinants of domestic water conflict and cooperation. Glob Environ Change. 2014;29:337–348. 100. Devlin C, Hendrix CS. Trends and triggers redux: climate change, rainfall, and interstate conflict. Political Geogr. 2014;43:27–39. 101. Moore S. The water wars within: preventing subnational water conflicts. In. New Security Beat. 2018. 102. Moore SM. Rethinking conflict over water. In: Oxford Research Encyclopedia of Environmental Science: Oxford, UK: Oxford University Press; 2016. 103. United Nations High Commissioner for Refugees. UNHCR Mid-Year Trends 2018. Geneva, Switzerland: Office of the United Nations High Commissioner for Refugees; 2018. 104. Lindley A. Leaving Mogadishu: towards a sociology of conflict-related mobility. J Refugee Stud. 2010;23(1):2–22. 105. Lubkemann SC. Migratory coping in wartime Mozambique: an anthropology of violence and displacement in fragmented wars. J Peace Res. 2005;42(4):493–508. 106. World Food Programme. At the Root of the Exodus: Food Security, Conflict and International Migration. Rome, Italy: World Food Programme; May 2017. 107. Taipale I, ed. War or Health? A Reader. London, UK: Zed Books; 2002. 108. Levy BS, Sidel VW. War and Public Health. Oxford, UK: Oxford University Press; 2008. 109. Levy BS, Sidel VW. Adverse health consequences of the Iraq War. Lancet. 2013;381(9870):949–958. 110. Hagopian A, Flaxman AD, Takaro TK, et al. Mortality in Iraq associated with the 2003– 2011 war and occupation: findings from a national cluster sample survey by the University Collaborative Iraq Mortality Study. PLoS Med. 2013;10(10):e1001533. 111. Roberts A. Lives and statistics: are 90% of war victims civilians? Survival. 2010;52(3):115–136. 112. Ascherio A, Chase R, Coté T, et al. Effect of the Gulf War on infant and child mortality in Iraq. N Engl J Med. 1992;327(13):931–936. 113. Ali M, Blacker J, Jones G. Annual mortality rates and excess deaths of children under five in Iraq, 1991–98. Popul Stud. 2003;57(2):217–226. 114. Aldridge RW, Nellums LB, Bartlett S, et al. Global patterns of mortality in international migrants: a systematic review and meta-analysis. Lancet. 2018;392:2553–2566. 115. Abubakar I, Aldridge RW, Devakumar D, et al. The UCL-Lancet Commission on Migration and Health: the health of a world on the move. Lancet. 2018;392(10164):2606–2654. 116. McMichael C, Barnett J, McMichael AJ. An ill wind? Climate change, migration, and health. Environ Health Perspect. 2012;120(5):646–654.

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117. Schwerdtle P, Bowen K, McMichael C. The health impacts of climate-related migration. BMC Med. 2018;16(1). 118. McMichael C. Climate change–related migration and infectious disease. Virulence. 2015;6(6):548–553. 119. de Brauw A. Migration and child development during the food price crisis in El Salvador. Food Policy. 2011;36(1):28–40. 120. Goldmann E, Galea S. Mental health consequences of disasters. Annu Rev Public Health. 2014;35(1):169–183. 121. Brabeck KM, Lykes MB, Hunter C. The psychosocial impact of detention and deportation on U.S. migrant children and families. Am J Orthopsychiatry. 2014;84(5):496–505. 122. Andersen GS, Kamper-Jørgensen Z, Carstensen B, Norredam M, Bygbjerg IC, Jørgensen ME. Diabetes among migrants in Denmark: incidence, mortality, and prevalence based on a longitudinal register study of the entire Danish population. Diab Res Clin Pract. 2016;122:9–16. 123. Wiist WH, Barker K, Arya N, et al. The role of public health in the prevention of war: rationale and competencies. Am J Public Health. 2014;104(6):e34–e47. 124. Kelman I, Mercer J, Gaillard JC, eds. The Routledge Handbook of Disaster Risk Reduction Including Climate Change Adaptation. New York, NY: Routledge; 2017. 125. Berry P, Enright P, Shumake-Guillemot J, Villalobos Prats E, Campbell-Lendrum D. Assessing health vulnerabilities and adaptation to climate change: a review of international progress. Int J Environ Res Public Health. 2018;15(12):2626. 126. Warner K. Global environmental change and migration: governance challenges. Glob Environ Change. 2010;20(3):402–413. 127. Biermann F, Boas I. Preparing for a warmer world: towards a global governance system to protect climate refugees. Glob Environ Politics. 2010;10(1):60–88. 128. McAdam J. Institutional governance. In. Climate Change, Forced Migration, and International Law. Oxford, UK: Oxford University Press; 2012:212–236.

9 Mental Health on a Changing Planet Susan Clayton

Rapidly changing environmental conditions are already taking a toll on global mental health, and that toll is expected to rise in coming decades. Mental health problems such as depression and anxiety are among the most significant health problems worldwide. The World Health Organization estimates that depression is the leading cause of disability, affecting more than 300 million people (4.4% of the global population) and that anxiety disorders affect 264 million (3.6%).1 Subclinical levels of mental problems can impair wellbeing and the ability to participate in society. Mental disorders have a significant economic cost as well: They may prevent people from working, and they can require expensive treatment. Poverty, in turn, can be cause and effect of both physical and mental health problems, creating the potential for feedback loops. This chapter distinguishes mental health from physical health, but they are tightly connected. Physical health problems can be a source of stress that impairs mental health, and the inverse is also true. Mental health issues can affect physical health, for example, through risky or sedentary behavior, substance abuse, or poor self-care. Furthermore, treatment for mental health can affect physical health: Most psychoactive medications have side effects, which include weight gain, sleepiness, and increased vulnerability to environmental conditions such as high temperatures. Finally, at a physiological level, mental and physical health are deeply intertwined. Stress levels tend to lead to higher blood pressure, which can threaten cardiovascular health. Mental health problems may interfere with sleep and depress the immune system, increasing morbidity and mortality from infectious diseases and increasing susceptibility to physical disease and accidents.

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The role of the social environment is also important. Problems with both physical and mental health can disrupt social networks, leading people to become isolated from friends and community. But research shows that strong social networks are highly protective against disease and death; the effect of loneliness and social isolation on health is considered to be at least as significant as that of smoking cigarettes.2 Environmental changes can weaken social networks in a number of ways, such as by dispersing communities, reducing community interactions, and increasing conflict, leading in turn to mental health problems through reduced social support. If we consider mental health not just as the absence of disease but as the achievement of a positive mental state, such as happiness or life satisfaction, the importance of social factors is obvious: Most people have a strong desire for social connections, and a feeling of belonging is necessary to a fulfilling life. Several pathways may link environmental conditions to mental health. Acute events such as crop failures, extreme weather, natural disasters, conflict, and pollution events can cause depression, anxiety, posttraumatic stress, and even suicide. Changes in ambient environmental conditions, such as pollution and high temperatures, can affect mental health and wellbeing also. And awareness of environmental threats is also a source of stress. Even for those who are not directly affected, worrying about climate change, degradation of cherished ecosystems and landscapes, species loss, and other environmental disruptions causes anxiety, grief, stress, and even despair. Finally, the potential for the environment to have positive impacts on mental health is increasingly recognized. Research ranging from large-scale epidemiological surveys to controlled experiments demonstrates that exposure to green spaces can reduce stress, lead to faster recovery from illness, and increase longevity. If environmental degradation reduces people’s exposure to healthy natural places, there are likely to be corresponding reductions in physical and mental wellbeing. The following sections explore the different categories of mental health impacts in more detail. We begin with discrete changes in environmental conditions—sudden events such as weather disasters and fires, and more gradual events such as droughts. Next, we consider ambient environmental conditions such as high temperatures and air pollution, and also the migration that is driven in part by environmental changes. Finally, we take a relational approach, considering human bonds with nature and place and the mental health implications of threatening those bonds. Although many impacts of environmental disruption on mental health have yet to be fully quantified, this uncertainty does not invalidate the serious implications of the connection.

Discrete Environmental Events Acute disasters such as hurricanes, severe droughts, wildfires, or floods are increasingly frequent events on our changing planet. The experience of living through such a disaster can be devastating (Figure 9.1). Trauma can result from personal experiences such

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Figure 9.1. The experience of a disaster can be devastating to mental health. Source: Andy Campbell (SurfAid International), Creative Commons, license CC BY-2.0

as injury, loss of property, or disruption in work activities but also from the experiences of others: injury or death of a loved one, breakdown of social ties in a community, even the loss of a beloved pet. People report terror, shock, and panic in initial response to natural disasters. Acute traumatic stress is the most commonly reported mental health problem, and some studies find increased rates of suicide.3 A meta-analysis of studies examining the impacts of natural disasters on mental health found between 7% and 40% of victims reporting some type of threat to mental health, including fear, general anxiety, depression, and somatic disorders.4 More recently, a meta-analysis looking specifically at posttraumatic stress disorder (PTSD) following a natural disaster reported cumulative incidence rates varying from 3.7% to 60%, with higher rates among first responders and those more directly affected by the disaster.5 These responses may persist long after the original event. Although some people recover after order has been restored, many continue to have trouble functioning. It can take time for transportation systems, businesses, educational and public institutions, utilities, and garbage collection to return to normal functioning, leading to increased stress. People may also feel vulnerable and anxious because of the unexpectedness of the disaster. Several years after a disaster, survivors experience higher prevalence of mental disorders relative to baseline; among some survivors, symptoms are still apparent 6 years

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or more after the event. In some instances, mental health problems increase in intensity or prevalence over time: For example, PTSD rates were higher a year after Hurricane Katrina than immediately after.6 Johannesson et al.7 suggest four possible postdisaster trajectories: resilience (no impact on mental health), recovery, delayed dysfunction, and chronic effects. Among several thousand Swedish citizens who experienced a tsunami in the Indian Ocean, the researchers found that 72% were resilient, 12% demonstrated recovery, and 16% showed some degree of chronic symptoms after 6 years. Those in the resilient group were likely to have experienced less severe trauma. Chronic sufferers tended to have a lower level of education, perhaps corresponding to less access to social support. Disasters may also affect health-related behaviors. Substance abuse increases after a natural disaster, as do cigarette smoking, sleep problems, and risky behavior in general.8 Disasters disrupt social interactions, leading to more job-related difficulties, interpersonal aggression, and domestic violence.9 Not everyone is equally affected. People who live in the hardest-hit areas or who experience major or multiple losses tend to experience the worst effects. Demographic predictors of vulnerability to depression following natural disasters include being female, unmarried, religious, and with limited education.10 In general, social connections are an important predictor of resilience.11 Individuals’ emotional responses also matter. Attachment to a particular place is associated with wellbeing, but damage to that place may reduce and even reverse the positive impacts of the setting on psychological health.12 In a study of Australian victims of bush fires, those who reported feelings of anger, directed both at the unfairness of the disaster itself and at authorities responsible for inadequate recovery programs, showed greater impacts on mental health, particularly among men.13 In addition to these individual factors, extrinsic factors play an important role. These include access to information, availability of resources and services, and strong psychological and social support networks that help people express and understand their own emotions.

Ambient Environmental Conditions Long-term, large-scale environmental changes are likely to affect far more people than do individual disasters. The ongoing, gradual shifts in temperature, precipitation, and sea level associated with climate change, the growing scarcity of fresh water and arable land, increasing pollution, and loss of coastal barrier systems such as mangrove forests, wetlands, vegetated dunes, and coral reefs are already affecting the habitability and safety of many parts of the world. These changes have direct mental health impacts and also drive population displacement and conflict, which have their own significant mental health implications, as discussed in Chapter 8.

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Heat Warming temperatures affect subjective wellbeing and therefore threaten mental health.14 Among 2 million randomly sampled U.S. residents between 2002 and 2012, warming of 1°C over a 5-year period was associated with a 2% increase in mental health problems.15 A careful analysis of county-level data from the United States and Mexico over several decades showed a clear relationship between heat and suicide rates that was not accounted for by income level or air conditioning penetration,16 although not all research has found this relationship. An analysis of Twitter posts in the same study found that higher temperatures were also associated with an increase in depressive language. Notably, there was no evidence of adaptation; the strength of the association remained fairly consistent over time. In India, there is evidence that heat waves are linked with both suicide and psychiatric hospitalizations.17 This association has been noted worldwide.18 Higher temperatures can also provoke increased aggression. This manifests in many ways: from pitchers beaning batters during baseball games19 and drivers aggressively honking their horns,20 all the way to violent crime, particularly when combined with frustration over limited access to resources such as fresh water or arable land (Figure 9.2). One analysis suggests that climate change could lead to increases in murder and rape.21 A meta-analysis of studies examining the link between climate conditions and various types of violence found a causal relationship between heat and aggression: As temperature goes up, so does interpersonal violence (ranging from violent retaliation in sports to rape and other violent personal crime) and, as discussed in Chapter 8, largerscale intergroup violence.22 By bringing formerly separate communities into contact,

Figure 9.2 There is a clear association between temperature and aggressive or violent behavior, from violent crime (left), to rape (center), to retaliation during baseball games (right). Source: Adapted from Hsiang S, Burke M, Miguel E. Quantifying the influence of climate on human conflict. Science 2013;341(6151):1235367

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environmental displacement also forces them to compete for resources such as jobs and land and thus contributes to conflict. Finally, heat stress can increase economic pressures and uncertainty,23 an additional source of anxiety.

Air Pollution Air pollution depresses mood and social relations while increasing anxiety and suicide risk.24 Psychotic episodes also rise with deteriorating air quality (perhaps explaining some of the excess of psychotic illness in urban areas compared with rural areas).25 Across the United States, psychological distress rises with air pollution, even after many physical, behavioral, and socioeconomic factors are controlled for.26 Air pollution has direct effects on brain function. It may also have indirect effects by reducing people’s tendency to spend time outside, an issue discussed further below. Interestingly, research based on 9 years of archival data in China found that levels of air pollution could be linked to crime and to unethical behavior at the city level. Follow-up experimental research that presented participants with photographs of Beijing on a day with high levels of pollution or on a clear sunny day confirmed the relationship, suggesting that the effect was at least partly due to an increase in anxiety associated with the polluted scenes.27 Pollution may thus degrade community cohesion as well as individual wellbeing.

Drought Prolonged or repeated drought is associated with emotional distress, particularly among those in rural areas whose livelihoods are connected to the land.28 In addition to depression and anxiety, suicide rates among farmers increase during periods of drought, perhaps principally because of the economic impact, although there is also evidence for the influence of other factors such as social isolation (Figure 9.3).29

Population Dislocation and Migration Changing environmental conditions will force some communities to abandon their homes and seek out new places to live. Displacement due to environmental conditions is increasing, as described in Chapter 8. The movement of people into cities is a dominant demographic trend (see Chapter 13), with the majority of people now living in cities and most human population growth in coming decades expected to be urban. Environmental factors (and associated economic factors) probably drive some of the rural–urban shift. Involuntary migration is a significant risk factor for mental health problems.30,31 The conditions that lead to migration are stressful, and the process of migrating is full of risk and uncertainty. Beyond that, migrants may be unwelcome in their new locations, leading to social tensions or outright conflict. As a result, up to 30% of migrants have PTSD and up to 50% suffer significant emotional distress.32 Even when conditions are

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Figure 9.3 An Australian farmer viewing his starving sheep during the 2018 drought. Depression rises among rural populations during events such as droughts. Source: Shutterstock

less stressful, migrants face increased mental health burdens associated with the need to learn to fit in, to develop new skills and new occupations, and to redefine their identity. A study of Mexican immigrants found elevated rates of major depression, panic disorder, anxiety disorder, and substance abuse disorder associated with “post-migration living difficulties.”33 Not only do immigrants face new social stressors, but the disruption to their community also weakens social networks that might otherwise provide an important source of support and resilience.

Urbanization Living in an urban environment has been linked to poorer mental health in cities around the world, even with risk factors such as socioeconomic status and parents’ mental health controlled for.34,35 Possible reasons for the effect of urbanization include stress, noise, and pollution. Reduced social cohesion may also play a role; social capital has been identified as a protective factor that reduces the impact of urbanization on mental health.36

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Reduced Access to Nature One aspect of the urban challenge may be reduced contact with nature. Western societies are increasingly removed from nature, with fewer opportunities to encounter the natural world and shrinking interest in engaging with it.37 A few generations ago, a far greater proportion of people lived in rural settings, in close contact with nature. Now both children and adults spend more time in their cars and less time walking; more time in their homes and less time in their yards. The loss of time spent in nature represents a serious public health problem. Nature contact provides a variety of benefits to both physical and mental health.38–40 These benefits operate across the lifespan, across cultures, across time scales from brief to prolonged, and across health states; there is some evidence that the benefits are greater for people of low socioeconomic status than for the more privileged.41,42 Exposure may take a variety of forms, from vegetation to seashores, from views out a window to living in a neighborhood with trees to immersive nature experiences. Researchers are now working to understand better the link between specific interactions with nature and particular beneficial outcomes (Figure 9.4).43 One of the best-studied forms of nature contact is neighborhood greenness, usually measured as the density of vegetation near where people live. A systematic review

Figure 9.4 Residents relaxing in New York City’s Central Park. Time spent in such settings has been shown to improve social cohesion and physical and mental health. Source: Corey Harmon (Flickr), Creative Commons, license CC BY-ND 2.0

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of twenty-eight studies, mostly European, found evidence that adults living in greener places had better mental health, defined broadly to include reduced levels of self-reported mental distress, anxiety, depression, and other outcomes.44 Nor is that association static; moving from a less green to a more green place,45,46 or living in a place that becomes more green,47 is associated with improvements in mental health. Other forms of nature contact linked to mental health include brief visits to parks,48 exercise in natural settings,49,50 immersive experiences such as “forest bathing” and wilderness hiking,51,52 and access to “blue space” (seashores, rivers, and lakes).53 These effects operate across the lifespan. Children exposed to nature—in green schoolyards, in their neighborhoods, in parks, in nature programs—show greater resilience, higher self-confidence, fewer behavioral difficulties, better academic performance, and less anxiety and depression.51,54,55 Moreover, low levels of nature contact in childhood predict worse mental health in adulthood.56,57 At the other end of life, although evidence is less plentiful, it appears that exposure to greenery is associated with improved mental health in older adults.58 Several specific mental health diagnoses are linked to reduced nature contact, including the most common mental health ailments: depression,59–61 anxiety,62 PTSD,63 and severe mental illness such as schizophrenia and bipolar disorder.64 Several explanations for the health benefits of nature contact are possible.65,66 Two complementary theoretical frameworks, both invoking psychological mechanisms, have been proposed: stress recovery theory, which emphasizes the role of nature in relieving stress, and attention restoration theory, which emphasizes the role of nature in relieving mental fatigue. Other potential mechanisms include the increase in physical activity associated with greenspaces, the social interaction associated with outdoor activity, and the reduced noise and improved air quality associated with vegetation—all predictors of better mental health. Some psychotherapeutic approaches rely on increasing experience with nature to promote mental health. Although few of these programs have been rigorously evaluated, there is some evidence for the effectiveness of outdoor or wilderness therapy.67 Ecopsychology is a clinically oriented subfield of psychology that claims to link declining mental health to a deterioration of the relationship between humans and nature, a relationship that is rooted in our evolutionary history and that promotes mental health by encouraging an improved relationship between people and the natural world. Contact with nature may also offer indirect benefits. Time spent in nature, perhaps particularly in childhood, contributes to the development of an environmental identity—a sense of oneself as connected to and interdependent with the natural world.68 This environmental identity, in turn, is associated with life satisfaction and wellbeing, and even vitality and resilience.69,70 It is also associated with pro-environmental attitudes and concern, perhaps through a greater sense of solidarity with the environment. (It is

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possible, though, that a high degree of nature connectedness can also make people more vulnerable to anxiety about the state of the environment.71) Reconnecting with nature may therefore offer a range of direct and indirect mental health benefits.40,72 It is impossible to predict the extent to which increased separation and alienation from nature will impair mental health or the extent to which new ways of connecting to nature will be able to compensate. However, some have suggested that the ruptured relationship with nature has already contributed to the increased levels of depression that have been documented worldwide.73 More specifically, many, if not most, people form attachments to specific environments that increase their sense of wellbeing.74 We turn next to how damage to those environments threatens place attachment and/or the benefit to health that those attachments create.

Breaching the Human Relationship with Our Planet: Impacts on Mental Health One of the most important frontiers in understanding the mental health impacts of accelerating environmental change is exploring how awareness of environmental change itself may be a growing source of mental distress. A variety of terms have appeared in the literature, including solastalgia, pretraumatic stress disorder, ecoanxiety, climate distress, and ecological grief. Based on their research among Inuit communities in the far north and Australian farmers, Cunsolo and Ellis75 offer a framework for “ecological grief” that includes three broad categories: grief associated with physical ecological losses, grief associated with loss of ecological knowledge and identity, and grief associated with anticipated future losses. The first category is similar to the impacts of acute events and changing ambient environmental conditions that are discussed above. The second category includes the grief associated with changing conditions that make deep knowledge of a place and its rhythms obsolete, as occurs among Inuit elders who are no longer able to predict travel routes across the ice or the behavior of animals that contribute to traditional diets, or Australian farmers who are no longer able to predict weather, pests, and crop yields as conditions change around them. The third category is the least well studied but perhaps the most pervasive. What are the mental health effects for far northern communities of knowing that their way of life and cultural identity are losing viability in a rapidly warming Arctic? On low-lying island nations, what are the mental health implications of knowing that future generations will not be able to live in the place where their ancestors have always dwelled? Around the world, how are people coping with the knowledge, released in the 2019 Intergovernmental Panel on Biodiversity and Ecosystem Services (IPBES) global assessment report, that up to a million species face extinction, many in the next few decades?76 Although there are not yet answers to these questions, there are growing indications that the state and trajectory of Earth’s natural systems are causing distress, and not only among Australian farmers and Inuit communities. In 2019 alone, expressions of anxiety

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about the state of the global environment exploded in social action including walkouts by tens of thousands of schoolchildren around the world, a BirthStrike movement centered in the United Kingdom in which women signaled their unwillingness to bring children into a world in environmental chaos,77 and the Extinction Rebellion, with a presence in more than forty countries around the world (as of 2019), protesting government inaction on climate change and accelerating rates of species extinctions (Figure 9.5).78 Popular press accounts and early research suggest that couples around the world are putting off having children, at least in part because of concerns about accelerating environmental change. They worry that their children will further burden an overtaxed planet or that environmental collapse will make the world inhospitable to their children.79 And there is no reason to believe that these concerns are restricted to couples in their childbearing years. Qualitative research indicates that people experience feelings of frustration, powerlessness, fear, anger, and exhaustion in response to environmental changes.80 For example,

Figure 9.5 Climate activists with the Birthstrike movement protest on September 20, 2019 in London. Protesters are pushing baby strollers carrying oil barrels stamped with messages such as “Where’s our future?,” “Carbon or kids?,” and “Where my baby could be.” There is growing evidence that one impact of accelerating environmental change is distress at the prospect of bringing children into an uncertain future. Source: Courtesy of Sarah Cresswell

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a 2018 survey found that 49% of Americans believe they personally will be harmed by global warming, and 56% believe their family will be harmed; 69% reported feeling somewhat or very worried (Figure 9.6).81 In surveys across many countries, substantial proportions of respondents report feeling very worried—20% in the United Kingdom and Australia, 40% in France, and nearly everybody in the existentially threatened Solomon Islands.82–84 In a small, nonrandom European sample, only 9% said they did not have worrying thoughts about the environment. Those who reported worrying cited global warming, pollution, extinction of species, resource depletion, and deforestation. Significantly, worrying about the environment was not associated with a more generalized tendency to worry, suggesting that it is not merely the case that habitual worriers are extending their concerns to the environment.85 For some people, the negative emotions relating to climate change are likely to be intense enough to contribute to mental illness.86 As described above, Australian farmers experiencing local changes from a disrupted climate have a diminished sense of identity, resulting in increased self-perceived risk of depression and suicide.87 They also report an “intense and pervasive sense of loss” associated with observing the effects of drought on the land.88 In a U.S. sample, perceived ecological stress, defined as personal stress associated with environmental problems, predicted depressive symptoms.89 The impacts of awareness of environmental change on mental health remain poorly quantified, but the potential effects of a general sense of anxiety, insecurity, and loss across a broad swath of humanity are beginning to emerge. Climate change is already associated with increases in the rate of anxiety and mood disorders, stress disorders, substance abuse, suicidal ideation, and grief.90 Although someone with many sources of support may find these feelings tolerable, they may also be a tipping point for those who have fewer resources or who are already experiencing other stressors. For example, one study of obsessive–compulsive disorder (OCD) sufferers (with the OCD checking subtype) found that 28% of the sampled patient population reported climate change concerns as a motivation for their compulsions.90

Inequity The mental health impacts of environmental change are inequitably distributed. Aiming for equity is crucial for moral reasons, but it is also important as a strategy for promoting mental health. Mental health problems are three times as prevalent in the most unequal societies as in the most equal societies, according to one study. This is probably caused by the impact of inequality on the fabric of social relationships—further evidence of the interconnectedness of mental health and community wellbeing.91 As is stressed throughout this book, environmental harms are unequally distributed. Poor communities and communities of color are more likely to live in areas that are contaminated by environmental toxins, such as industrial waste and landfills, as well as less

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Figure 9.6 Trends in Americans’ views of climate change. Note increasing concern over the 5-year period 2013 to 2018. Source: Yale Program on Climate Change Communications and George Mason University Center for Climate Change Communications

likely to have access to environmental goods, such as parks, gardens, and urban trees. The impacts of large-scale, anthropogenic, environmental disruption are also inequitable, both because they are not equally distributed spatially or temporally and because their impacts are disproportionately experienced by those with the fewest resources to mediate them. In general, those who are financially disadvantaged are at greater risk because they

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have reduced access to health care and to the economic resources that could mediate their exposure and help them recover (see Figure 1.4 for mediating factors). Differential exposure, in turn, can increase vulnerability to environmental hazards. Indigenous communities are disproportionately affected by living in more geographically vulnerable areas and being more intimately connected with nature. These contacts with nature can be a source of health and wellbeing, for example by encouraging physical activity and promoting social connections and cultural identity, but they can also bring heightened awareness of environmental degradation and vulnerability to environmental hazards and thus cause anxiety about environmental changes.92 Indigenous communities in the far North and Oceania are already reporting social and psychological burdens associated with changing environmental conditions. Some Indigenous communities are forced to leave their traditional locations, and many communities can no longer engage in certain culturally significant practices, such as those associated with natural resource use, that have typically been passed down across generations. The result is a reduction in important social interactions and a decreased sense of cultural identity, contributing to higher levels of suicide and substance abuse.93 In Canada, Inuit communities report suicide rates as much as eleven times higher than the Canadian average, even higher among teenagers; this difference is not exclusively associated with environmental factors, but changing patterns of interaction with the environment play a role.86 Similarly, certain occupational groups are more threatened by environmental changes, particularly those who work in close contact with the land or who derive significant benefit from the use of natural resources, for example through hunting, fishing, or agriculture. Farmers are known to be at particular risk of depression,94 and as discussed above, droughts in several parts of the world (Australia, India) have led to spikes in farmer suicide,95 although the mechanism for this effect is debated. Vulnerability can also arise from social factors. The fact that Indigenous and minority communities tend to experience more environmental hazards is partly attributable to their lack of social, political, and economic power: They have been less able to advocate for their own interests in discussions of policies, zoning, and development. Women, similarly, are considered particularly vulnerable to climate change because of the ways in which gender roles have limited their autonomy and their access to information. Traditional roles, such as caregiving for children and responsibility for collecting firewood or water, mean that they will be more affected by environmental changes that limit resource availability and increase hazardous exposure. Children are especially vulnerable to environmental hazards—an important observation because of the way in which the consequences persist and spread into the future. Social factors contribute to children’s vulnerability, because their dependence on others

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makes them more likely to experience vicarious as well as direct impacts. In addition, they are physiologically vulnerable. The fact that their bodies and brains are still developing makes them both more susceptible to lasting impact and less resilient in their ability to recover from impact. The mental health consequences for children can also be disproportionate. They tend to show more extreme responses, such as PTSD and depression, in the aftermath of natural disasters and forced migration.3 Their dependence on caregivers means that separation from those caregivers, and the caregivers’ own negative emotions, can be additional sources of stress. Indeed, Juth et al.96 found that parents’ PTSD symptoms were associated with those of their children after a major earthquake in Indonesia, and they argue for thinking about the impacts of disasters on social units rather than on individuals, particularly for parent–child dyads. Of particular concern, environmental events may have irreversible impacts on children by stunting or modifying their natural development. The experience of significant stress during childhood may sensitize the brain, leading to more pronounced stress reactions later in life.97 Other groups are physiologically vulnerable to environmental impacts. People with preexisting mental illness are likely to be particularly affected because their coping systems are already taxed, and maintaining a regular daily routine is an important part of their functioning; because psychoactive medications may amplify the effects of heat; and because disruptions to the medical care system may prevent them from receiving needed care.18 Older adults are also more strongly affected by heat and are more likely to develop mental health problems after natural disasters.98 Like children, older adults face social as well as physiological vulnerabilities, with less flexibility to adapt to lifestyle changes in residence or occupation, and more social isolation; they also show more resistance to using mental health services.99

Mental Health in the Anthropocene: Toward a Positive Relationship between Humans and the Planet The magnitude and range of current and potential impacts of environmental degradation on mental wellbeing call for a significant effort to mitigate that degradation and to consider ways of adapting to new environmental realities. But the widespread tendency to ignore environmental impacts and even deny the reality of some changes, such as climate change, remains a barrier. Denial is motivated by a number of different factors: Cognitive and emotional distance from the phenomena of environmental change, emotional reluctance to confront the frightening implications, and ideological resistance can all lead people to ignore the evidence. Although political ideology is one of the strongest barriers, denial can also be motivated by religious belief, faith in technology, or simply support for a comfortable if high-consuming lifestyle. Thus disagreements (e.g., about climate

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change) are not usually about the facts but about “the implications the issue holds for society.”100 Attempts to convince people to respond appropriately to environmental challenges require attending to the understandings that each audience brings to the issue. Adaptation is an increasingly important part of the discussion about responses to environmental change. Adaptation emphasizes changes in the ways in which people interact with the natural environment, requiring changes not only in physical infrastructure, building codes, and agricultural practices but also in social relationships and individual behavior. For example, the negative effects of urbanization are not inevitable; contact with nature can be maintained, perhaps even enhanced, if cities are well designed to include parks, trees, and gardens, as discussed in Chapter 13. Society should consider the possibility of a “transformation of experience” rather than “extinction of experience.”101 Fortunately, efforts to address global environmental change can yield benefits for mental wellbeing. Two in particular are worth highlighting. First, individual involvement can contribute to a sense of meaning and purpose. Multiple studies have found correlations between sustainable behaviors and happiness, as people who feel that they are contributing to positive efforts feel better about themselves, their values, and their efficacy.69,102 Studies also show that engaging in behavior to mitigate climate change, even among those who perceive the threat as severe, is associated with reduced distress and depressive symptoms.89,103 Second, involvement in collective social action is likely to strengthen social ties, an important source of resilience in the face of both physical and mental risk factors (Figure 9.7). Not only does participation in group-level initiatives have the potential to strengthen a sense of efficacy and empowerment; it can also build feelings of belonging and collective identity that are associated with positive emotions as the group becomes a source of support that is linked to subjective wellbeing.104 Australian psychiatrist Helen Berry described a local initiative to improve the social functioning of a disadvantaged community during a drought, and she described a positive impact on mental health. She argued that such community-based interventions would be more effective than individually focused measures in alleviating the mental health consequences of drought and referred to this opportunity as a “pearl in the oyster.”105 As we look toward an uncertain and potentially frightening future in which harmful environmental impacts are likely to increase and beneficial impacts decrease, it is important to remember that individuals and communities are not just passive recipients of environmental influence. They have agency and can take steps to become more resilient to negative environmental changes.92 Individuals will be in a better position to the extent that they are informed and prepared, have strong social connections, believe in their own coping abilities, take part in collective action, and maintain a sense of optimism. Although characteristics such as being informed, connected, and optimistic are attributes of individuals, they can be fostered or undermined by the social context.

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Figure 9.7 A demonstration by Mothers Out Front, an advocacy group active in the fight against climate change. Collective action to address global environmental change by speaking out or building community resilience may offer mental health benefits. Source: Photograph by Emily Rose, used with permission

Communities can foster resilience by creating communication channels to provide people with information about future threats, current conditions, effective preparations, and available resources and by ensuring that these communication channels reach everyone. They should also create ways for citizens to participate in planning and policy decisions. Such community initiatives will also connect and empower individuals and make them more optimistic about the community’s ability to cope with coming challenges. Communities can do more than inform and connect individuals; they should consider how their own characteristics may constitute weaknesses as well as strengths in the face of environmental challenges. Asset and vulnerability analysis allows communities to inform themselves about the particular environmental risks they face and existing resources (social, economic, physical) that can be used to strengthen resilience. Significantly, one aspect of effective systems is diversity, which tends to increase flexibility and the ability to adapt to changing circumstances. Diversity can be defined in many ways, but it generally includes human variability. A range of experience, knowledge, skills, and vulnerabilities will help communities and societies recognize the potential impacts of environmental changes and develop potential solutions or accommodations.

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Conclusions There is strong and increasing evidence for the impacts of environmental change on mental health. In addition to the direct effects of discrete environmental events such as natural disasters, there is reason for concern about the more gradual changes in environmental conditions that affect how people experience the natural world. And the ways in which people understand their relationship with the natural world and anticipate future changes are relevant to their psychological wellbeing. As the research reviewed here shows, social context can be vital in promoting a positive relationship between humans and nature, as well as buffering the impacts of environmental stressors. Considering the connections between human and ecological wellbeing is important in order to understand the factors that inhibit, or alternatively promote, human flourishing. It is also important for encouraging the recognition of our interdependence with the natural world. Although environmental protection is sometimes seen as an altruistic act that overrides self-interest, in fact it is more accurately described as protection of the planetary system of which we are all a part, and thus it is fundamentally an act of selfpreservation. Paying attention to the relationship between humans and our planet will encourage us to design healthier built environments, to promote contact with nature, and to implement policies that protect both our planet and our physical and our mental health.

Author Susan Clayton, PhD is Whitmore-Williams Professor of Psychology at the College of Wooster in Ohio. She has written or edited six books, including most recently Psychology and Climate Change (2018; co-edited with Christie Manning). She is a lead author on the upcoming sixth assessment report from the Intergovernmental Panel on Climate Change.

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Iwata Y, Dhubháin ÁN, Brophy J, Roddy D, Burke C, Murphy B. Benefits of group walking in forests for people with significant mental ill-health. Ecopsychology. 2016;8(1):16–26.

65. Kuo M. How might contact with nature promote human health? Exploring promising mechanisms and a possible central pathway. Front Psychol. 2015;6. 66.

Frumkin H, Bratman GN, Breslow SJ, et al. Nature contact and human health: a research agenda. Environ Health Perspect. 2017.

67. Bettmann JE, Gillis HL, Speelman EA, Parry KJ, Case JM. A meta-analysis of wilderness therapy outcomes for private pay clients. J Child Fam Studies. 2016;25(9):2659–2673. 68. Rosa CD, Collado S. Experiences in nature and environmental attitudes and behaviors: setting the ground for future research. Front Psychol. 2019;10. 69. Olivos P, Clayton S. Self, nature and well-being: sense of connectedness and environmental identity for quality of life. In. Handbook of Environmental Psychology and Quality of Life Research. Berlin, Germany: Springer International Publishing; 2016:107e126. 70. Zelenski JM, Nisbet EK. Happiness and feeling connected: the distinct role of nature relatedness. Environ Behav. 2014;46(1):3–23. 71.

Dean JH, Shanahan DF, Bush R, et al. Is nature relatedness associated with better mental and physical health? Int J Environ Res Public Health. 2018;15(7):1371.

72. Ives CD, Abson DJ, von Wehrden H, Dorninger C, Klaniecki K, Fischer J. Reconnecting with nature for sustainability. Sustain Sci. 2018;13(5):1389–1397. 73. Hidaka BH. Depression as a disease of modernity: explanations for increasing prevalence. J Affect Disord. 2012;140(3):205–214. 74. Knez I, Butler A, Ode Sang Å, Ångman E, Sarlšv-Herlin I, Åkerskog A. Before and after a natural disaster: disruption in emotion component of place-identity and wellbeing. J Environ Psychol. 2018;55:11–17. 75. Cunsolo A, Ellis NR. Ecological grief as a mental health response to climate changerelated loss. Nat Clim Change. 2018;8(4):275–281. 76. IPBES. Summary for Policymakers of the Global Assessment Report on Biodiversity and Ecosystem Services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Bonn, Germany: IPBES Secretariat; 2019. 77. Hunt E. BirthStrikers: meet the women who refuse to have children until climate change ends. Guardian. 12 March, 2019. 78.

Feder JL. Extinction rebellion shut down London to shock people into facing the reality of climate change. That was just the beginning. BuzzFeed. 12 July, 2019.

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79. Scheinman T. The couples rethinking kids because of climate change. BBC, 1 October 2019. https://www.bbc.com/worklife/article/20190920-the-couples-reconsidering-kids -because-of-climate-change. Accessed April 2020. 80.

Moser SC. More bad news: the risk of neglecting emotional responses to climate change information. In: Creating a Climate for Change. Cambridge, UK: Cambridge University Press; 2007:64–80.

81. Leiserowitz A, Maibach E, Rosenthal S, et al. Climate Change in the American Mind. New Haven, CT: Yale Program on Climate Change Communication George Mason University Center for Climate Change Communication; 2018. http://climatecommunication .yale.edu/publications/climate-change-in-the-american-mind-december-2018. 82. Steentjes K, Pidgeon N, Poortinga W, et al. European Perceptions of Climate Change: Topline Findings of a Survey Conducted in Four European Countries in 2016. Cardiff, Wales: Cardiff University; 2017. 83. Asugeni J, MacLaren D, Massey PD, Speare R. Mental health issues from rising sea level in a remote coastal region of the Solomon Islands: current and future. Australas Psychiatry. 2015;23(6 suppl):22–25. 84. Reser J, Bradley G, Glendon A, Ellul M, Callaghan R. Public Risk Perceptions, Understandings, and Responses to Climate Change and Natural Disasters in Australia, 2010 and 2011. Southport, Australia: National Climate Change Adaptation Research Facility, Gold Coast; 2012. 85.

Verplanken B, Roy D. My worries are rational, climate change is not: habitual ecological worrying is an adaptive response. PLoS One. 2013;8(9):e74708.

86.

Bourque F, Willox AC. Climate change: the next challenge for public mental health? Int Rev Psychiatry. 2014;26(4):415–422.

87. Ellis NR, Albrecht GA. Climate change threats to family farmers’ sense of place and mental wellbeing: a case study from the Western Australian Wheatbelt. Soc Sci Med. 2017;175:161–168. 88. Polain JD, Berry HL, Hoskin JO. Rapid change, climate adversity and the next big dry: older farmers’ mental health. Aust J Rural Health. 2011;19(5):240. 89. Helm SV, Pollitt A, Barnett MA, Curran MA, Craig ZR. Differentiating environmental concern in the context of psychological adaption to climate change. Glob Environ Change. 2018;48:158–167. 90. Jones MK, Wootton BM, Vaccaro LD, Menzies RG. The impact of climate change on obsessive compulsive checking concerns. Aust N Z J Psychiatry. 2012;46(3):265–270. 91. Wilkinson R, Pickett K. The Spirit Level: Why Greater Equality Makes Societies Stronger. New York, NY: Bloomsbury Press; 2011. Accessed April 2020. 92. Durkalec A, Furgal C, Skinner MW, Sheldon T. Climate change influences on environment as a determinant of Indigenous health: relationships to place, sea ice, and health in an Inuit community. Soc Sci Med. 2015;136–137:17–26. 93. MacDonald JP, Willox AC, Ford JD, Shiwak I, Wood M. Protective factors for mental health and well-being in a changing climate: perspectives from Inuit youth in Nunatsiavut, Labrador. Soc Sci Med. 2015;141:133–141. 94. Truchot D, Andela M. Burnout and hopelessness among farmers: the Farmers Stressors Inventory. Soc Psychiatry Psychiatr Epidemiol. 2018;53(8):859–867.

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95. Parida Y, Dash DP, Bhardwaj P, Chowdhury JR. Effects of drought and flood on farmer suicides in Indian states: an empirical analysis. Econ Disaster Clim Change. 2018;2(2):159–180. 96.

Juth V, Silver RC, Seyle DC, Widyatmoko CS, Tan ET. Post-disaster mental health among parent–child dyads after a major earthquake in Indonesia. J Abnorm Child Psychol. 2015;43(7):1309–1318.

97. McLaughlin KA, Kubzansky LD, Dunn EC, Waldinger R, Vaillant G, Koenen KC. Childhood social environment, emotional reactivity to stress, and mood and anxiety disorders across the life course. Depress Anxiety. 2010;27(12):1087–1094. 98.

Parker G, Lie D, Siskind DJ, et al. Mental health implications for older adults after natural disasters: a systematic review and meta-analysis. Int Psychogeriatr. 2015;28(1):11–20.

99. Polain JD, Berry HL, Hoskin JO. Rapid change, climate adversity and the next big dry: older farmers’ mental health. Aust J Rural Health. 2011;19(5):239–243. 100. Markowitz EM, Guckian ML. Climate change communication: challenges, insights and opportunities. In: Clayton S and Manning C, eds. Psychology and Climate Change: Human Perceptions, Impacts, and Responses. Amsterdam, The Netherlands: Elsevier;2018:35–63. 101. Clayton S, Colléony A, Conversy P, et al. Transformation of experience: toward a new relationship with nature. Conserv Lett. 2017;10(5):645–651. 102. Howell AJ, Passmore H-A. The nature of happiness: nature affiliation and mental wellbeing. In: Keyes CLM, ed. Mental Well-Being: International Contributions to the Study of Positive Mental Health. Berlin, Germany: Springer Netherlands; 2012:231–257. 103. Bradley G, Reser J, Glendon AI, Ellul M. Distress and coping in response to climate change. In: Kaniasty K, Moore K, Howard S, Buchwald P, eds. Stress and Anxiety: Applications to Social and Environmental Threats, Psychological Well-Being, Occupational Challenges, and Developmental Psychology. Berlin, Germany: Logos Verlag; 2014:33–42. 104. Bamberg S, Rees JH, Schulte M. Environmental protection through societal change. In: Clayton S and Manning C, eds. Psychology and Climate Change: Human Perceptions, Impacts, and Responses. Amsterdam, The Netherlands: Elsevier; 2018:185–213. 105. Berry H. Pearl in the oyster: climate change as a mental health opportunity. Australas Psychiatry. 2009;17(6):453–456.

10 Climate Change and Human Health Howard Frumkin

The other chapters in this portion of the book explore the impacts of a broad range of environmental changes on specific dimensions of human health and wellbeing: nutrition, infectious disease, noncommunicable diseases, dislocation and conflict, mental health, and happiness. But in recent years, the health impacts of one particular environmental change—global climate change—have received great attention. In this short chapter, we break pattern and explore how one environmental driver, climate change, threatens nearly every dimension of human health. As described in the climate change section of Chapter 4 and illustrated in Figure 4.1, the combustion of coal, oil, and gas—which consist of carbon-based molecules—predictably releases the oxidation product carbon dioxide (CO2) into the atmosphere. Although the resulting changes in the composition of our atmosphere have been relatively modest—measured in hundreds of parts per million—the impacts on humanity and the rest of the biosphere are dramatic and far-reaching. Illustrating one of the core themes of planetary health, this modest change in the chemical composition of the atmosphere ripples through multiple physical and biological systems to affect nearly all of life on Earth. CO2 (together with other chemicals, such as methane, nitrous oxide, and chlorofluorocarbons) acts as a greenhouse gas, trapping radiant energy at the earth’s surface and functionally turning up the planet’s thermostat. The higher levels of trapped energy cause global average temperatures to rise. The warming itself is leading to more intense and frequent natural disasters including severe storms, droughts, heatwaves, floods, and wildfires. It is leading to thermal expansion of water and melting of land-based ice, particularly at the poles, causing sea-level rise. More trapped

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energy also changes hydrological cycles: There are more extreme precipitation events, wet areas become wetter, and dry areas become drier. In addition, higher CO2 levels in the atmosphere have direct effects independent of warming, including acidification of the oceans and alteration of growth patterns and chemical composition of many plants. These changes in turn have a wide range of impacts on oceans and rivers, on glaciers and land, on plants and animals—and on people. The impacts on people can be divided into several categories: temperature-related effects, the effects of severe weather and disasters, the impact of reduced air quality, aggravation of allergies, increased risk of infectious diseases, nutritional effects, population displacement, civil conflict, and mental health impacts. These occur through a range of complex and multilevel pathways, as shown in Figure 10.1. Some impacts are direct, such as the injuries that occur in a climate-related disaster. Some are indirect, such as nutritional challenges that result from climate impacts on crops. And some, such as conflict, are tertiary, mediated by social processes. The health effects of climate change have been extensively inventoried and reviewed by the Intergovernmental Panel on Climate Change1 and the World Health Organization,2 by the federal government,3,4 in academic journals,5–9 and in books.10–12 Accordingly, this chapter provides just a brief summary. Importantly, although everybody everywhere is vulnerable to some of the effects of climate change, not everybody is equally vulnerable. Wealthy nations are far more resilient than poor nations, which will be especially hard hit. Within any country or community, poor people are more vulnerable than those who are better off.13 Certain other subpopulations are especially vulnerable; these include children,14 older adults,15 and people with certain medical conditions. And future generations, given the trajectory of climate change, will be more vulnerable than those of us alive today.16

Temperature-Related Effects Excessive heat—both during severe heatwaves and as a long-term “new normal” (Figure 10.2)—threatens health and wellbeing in numerous ways. Medical consequences range from minor, self-limited conditions such as heat rash and cramping to severe and possibly fatal outcomes such as heat stroke. More consequentially from a population point of view, mortality rates rise during periods of heat, mostly because of increases in cardiovascular deaths.17 For example, the 1995 Chicago heatwave caused approximately 700 excess deaths,18 the 2003 European heatwave had an impact two orders of magnitude higher at an estimated 70,000 excess deaths,19 and the 2010 Russian heatwave caused 11,000 excess deaths.20 In addition to these lethal effects, heat is associated with a range of other impacts, from increased risk of kidney stones21 and chronic renal disease22 to impaired sleep,23 from increased violence24 and possibly suicide25 to substantial reductions in work capacity (with serious social and economic consequences).26,27 As more people settle in cities (see Chapter 13), their exposure to heat is aggravated by the urban heat

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Figure 10.1 Pathways from climate change to health outcomes, showing both direct impacts and indirect impacts mediated through complex environmental and social processes. The figure is not intended to be comprehensive. Source: Frumkin H, Haines A. Global environmental change and noncommunicable disease risks. Annu Rev Public Health. 2019;40:261–282, adapted from McMichael AJ. Globalization, climate change, and human health. N Engl J Med. 2013;368:1335–1343

island effect: the tendency of cities to be warmer than nearby rural areas because of the dark surfaces that absorb and reradiate heat, the loss of vegetation that would otherwise provide cooling through evapotranspiration, and the concentrated local generation of heat.28 Similarly, heat not only creates its own risks but also reduces air quality by driving ground-level ozone formation; ozone is a respiratory toxin.29 In coming years, warmer weather will reduce the number of cold-related deaths in some places but not enough

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Figure 10.2 With continued warming of the planet, higher temperatures will become the “new normal,” as suggested by the shifting temperature distribution shown in this diagram. Source: Battisti DS, Naylor RL. Historical warnings of future food insecurity with unprecedented seasonal heat. Science. 2009;323:240–244

to compensate for projected increases in heat-related deaths; a study of more than 200 American cities predicted a net increase of thousands of excess deaths each year by the end of this century without adaptation.30 Certain populations such as the poor, those who are socially isolated, people of color, the very young and very old, people with certain medical conditions, and outdoor workers are at especially high risk from severe heat.31–33

Severe Weather and Disasters Severe weather events have been rising in frequency in recent decades, and continued increases are predicted.34–36 Such events are dangerous. Floods, forest fires, hurricanes, and severe storms can cause traumatic injuries and death at the time of their occurrence. Other health impacts can persist well beyond the acute phase. In the short term, for example, before power is restored, people who use propane burners and generators risk carbon monoxide poisoning.37 Disasters often disrupt medical care and can destroy clinical facilities, interfering with acute and chronic medical care.38,39 After floods, homes can experience extensive mold growth, posing respiratory risks.40 Large-scale fires cause precipitous drops in air quality.41 In contrast to fires and severe storms, droughts unfold more slowly, over months to years, threatening health in a range of ways: crop failures and malnutrition, infectious disease risks due to reduced water quality and quantity, respiratory risks due to reduced air quality, and mental health risks.42 In the aftermath of disasters, people’s lives may be upended and their livelihoods compromised, and they may be forced to relocate; these outcomes increase the risks of infectious diseases and malnutrition (in resource-poor areas)43 and threaten mental health, as reflected in elevated rates of anxiety, depression, posttraumatic stress disorder,

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substance abuse, and domestic violence following disasters.44 Deprived populations, such as poor and minority communities, and communities located in vulnerable places, are at greater risk from disasters caused or intensified by climate change,13,33 as are children.14

Air Quality As explained in Chapter 12, the combustion of fossil fuels—a root cause of climate change—is also a leading source of many air pollutants. Climate change affects air quality in at least two other important ways.45 First, warmer temperatures drive the formation of ground-level ozone.46 Higher ozone levels are reflected in increases in respiratory symptoms, lost work and school days, hospital and emergency department visits, and premature deaths. Second, drier, hotter weather and degraded forests (due to such factors as pest infestations) result in more frequent wildfires (Figure 10.3).47 Wildfires release large amounts of smoke, a cardiopulmonary risk for those downwind.48 Children and people with respiratory conditions such as asthma are especially susceptible to the effects of air pollutants.

Figure 10.3 The Camp Fire, northern California, in a November 2018 satellite image. This was the deadliest wildfire in California history. The toll was 85 deaths, more than 18,000 buildings destroyed, and total damages of more than $16 billion. Air quality in San Francisco and California’s Central Valley was seriously affected, increasing cardiopulmonary risk for people living there. Source: Photo by Joshua Stevens (NASA)

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Allergies Climate change can exacerbate allergies in several ways. First, some allergenic plants such as ragweed and certain allergenic trees experience faster growth and a prolonged growing season, a trend that has been documented in many parts of the United States.49,50 Second, these plants can produce more pollen (Figure 10.4).51 Third, the amount of allergenic proteins contained in pollen can increase.52,53 The result is increased suffering for people with allergies.54

Infectious Diseases Climate change is likely to increase the risk of infectious diseases in many places.55 Two main categories of disease are especially salient: vector-borne diseases and waterborne and foodborne diseases. Vector-borne diseases are those that are spread by mosquitoes, ticks, and similar organisms.56 Mosquitoes transmit such diseases as dengue fever,57 malaria,58 and West Nile

Figure 10.4 Rising ragweed pollen counts with rising CO2 levels. Source: Adapted from Ziska L, Caulfield F. Rising CO2 and pollen production of common ragweed (Ambrosia artemisiifolia), a known allergy-inducing species: implications for public health. Aust J Plant Physiol. 2000;27:893–898.

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virus,59 and ticks transmit such diseases as Lyme disease.60 As discussed in more detail in Chapter 6, many features of climate change can promote disease spread: changes in rain patterns that enhance mosquito habitat; changes in temperature that accelerate vector metabolism, breeding, and feeding; and changes in vegetation that favor tick proliferation.61 Some vector-borne diseases, such as Lyme disease, have expanded their geographic range or seasonal distribution in recent years, a trend that is expected to continue in coming decades.60,62 Vector-borne disease spread is complex and depends on many factors other than climate change, such as land use changes and the use of protective strategies (such as window screens and insect repellant). But continued climate change is likely to increase risks. Also important are infectious diseases transmitted by water and food, such as cholera,63 salmonella, and campylobacter.64 The risk of these conditions may increase because of changes in hydrology, pathogen biology, and other factors. Two cardinal features of climate change drive increases in waterborne diarrheal diseases: warm weather65 and heavy rainfall.66 This suggests that continued climate change will increase the risk of waterborne infections. Foodborne diseases and waterborne diseases are closely linked, because food is often contaminated by water and because the conditions that promote one also promote the other. Accordingly, climate change is expected to increase the risk of foodborne diseases as well.67

Nutrition Although climate change will bring increased agricultural productivity to some regions, such as northern Canada and Russia, many more places will suffer declines. Climate change threatens agriculture through complex pathways, including the effects of extreme heat, storms, droughts, and flooding; pests and weeds; and rising ozone levels,68–70 a topic explored in more detail in Chapter 5. Compounding these impacts on crops themselves is reduced work capacity among farmers.27 The quantity of crops produced is not the only concern; quality also suffers. The protein and micronutrient content of some grains and legumes, including wheat, rice, corn, and soy, declines with rising atmospheric concentrations of CO2.71 Modeling studies indicate that hundreds of millions of people will experience increased risk of micronutrient and protein deficiencies as a result.72 Dietary quality may suffer in another way: through higher levels of salt in the drinking water (and therefore the food) of some coastal populations. In Bangladesh, for example, the combination of sea-level rise and poor water resource management has led to saltwater intrusion into coastal aquifers. The increased groundwater salinity raises the risk of high blood pressure for those drinking the water and using it for cooking73 and also increases the risk of preeclampsia and gestational

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hypertension in pregnant women.74 Yet another pathway from climate change to food quality operates through chemical contamination. Farmers may increase their pesticide use in response to more intense insect infestations75 and increase their herbicide use in response to greater competition by weeds and reduced herbicide efficacy.76 In addition to crops, climate change also threatens animal-based foods. Fish are a substantial source of dietary protein for many populations, but global fisheries, already compromised by overfishing,77 are threatened by climate change, especially at low to mid-latitudes,78,79 and aquaculture—potentially an important adaptation—is particularly threatened by ocean acidification.80,81 Livestock production, including animal growth and milk production, declines with hot weather and other features of climate change.82 When food supplies fall short of demand, prices rise, a special hardship for people who are food-insecure, including nearly one in eight households in the United States.83 Families that have difficulty making ends meet tend to purchase less costly, less nutritious, calorie-dense foods,84,85 which contribute to a range of chronic diseases.

Population Displacement In much of the world, human habitation is concentrated in places that are vulnerable to climate change: along coasts and rivers and in warm climates. As explored in Chapter 8, some populations may be displaced by climate change as drought, sea-level rise, and severe weather events create localized shortages of food, water, and habitable land and exacerbate underlying social, political, and economic stressors.86,87 People may relocate urgently, such as after a major disaster, or more deliberately and over a longer time, as their communities become progressively less habitable (or as it becomes prohibitively expensive to keep them habitable).88–90 According to the UN High Commissioner for Refugees, as of 2019 there were 68.5 million displaced people worldwide, more than half of them children—the highest total yet recorded.91 Many of these people were forced to relocate by conflict or persecution; environmental change contributed in many circumstances. Key health risks among displaced populations relate to infectious diseases, nutrition, reproductive health, and mental health and psychosocial stressors.92,93

Civil Conflict Worsening pressure on increasingly scarce resources, displaced populations, and other destabilizing forces are risk factors for civil conflict,94-96 a topic explored in more detail in Chapter 8. Changing weather patterns due to climate change may have contributed to the Darfur conflict in the first decade of the twenty-first century97 and to the uprisings in Syria and Egypt in the next decade98 (although these are complex processes, and other factors played a role as well). The implications for health are both direct, threatening combatants and civilians caught up in conflicts, and indirect, diverting funds from health

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and other essential human services. At a more granular scale, warming temperatures are associated with higher levels of interpersonal violence,24 resulting in injuries and fatalities, lasting psychological damage, and other harms.99

Mental Health Impacts As described more fully in Chapter 9, climate change and environmental degradation can threaten mental health in several ways. Disasters such as floods and hurricanes often result in large population burdens of depression, anxiety, and other manifestations of posttraumatic stress.100 The ongoing interruption of place attachment; the loss of accustomed weather patterns, biodiversity, and other environmental features; and the insecurity that comes with uncertainty about the future can trigger grief, distress, anxiety, and other mental disorders.101,102 People with mental illnesses are also more susceptible to heat because of the side effects of certain medications, inappropriate behavioral responses, or abnormal physiological homeostatic mechanisms.103

Surprises One of the recurring themes in planetary health is that modest changes in one system— the chemical composition of the atmosphere, in this case—can lead to a cascade of effects across other physical and biological systems, with consequences that are hard to predict. That more trapped energy on the planet would lead to rising temperatures, causing ice melting and thermal expansion of water, had long been predicted. But that the resulting sea-level rise would cause saltwater intrusion into coastal aquifers and increase the risk of preeclampsia and gestational hypertension among Bangladeshi women was something nobody anticipated. Nor would it have been easy to anticipate that modest increases in atmospheric CO2 would make our food less nutritious and put hundreds of millions of people at increased risk of micronutrient deficiencies. The complexity of Earth’s systems and their even more complex interactions make it highly likely that we will continue to encounter unanticipated health impacts of climate change and other types of anthropogenic environmental change.

Conclusions Although many global environmental changes can threaten human health, climate change is one of the best understood. The links between climate change and health exemplify several principles. First, climate change increases the risk of almost every form of human suffering: infectious diseases, chronic diseases, poor mental health, injuries, disrupted lives. Second, the effects operate through many pathways, some direct and others indirect. Third, not everybody is equally vulnerable; some populations are at especially high risk, for a variety of reasons. Fourth, although the health threats are manifesting now,

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they are certain to worsen in the future as climate change progresses. Finally, although some adaptation is possible and necessary to protect people from climate impacts, the only definitive solution is primary prevention: reversing climate change and achieving a stable climate. This mandate brings with it a host of opportunities to promote health, a theme explored more fully in Chapter 18.

Author Howard Frumkin, MD, DrPH is professor emeritus of environmental and occupational health sciences, and former dean, at the University of Washington School of Public Health.

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33. Gamble JL, Balbus J, Berger M, et al. Populations of concern. In: Crimmins A, Balbus J, Gamble JL, et al., eds. The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment. Washington, DC: U.S. Global Change Research Program; 2016:247–286. 34. Donat MG, Lowry AL, Alexander LV, Ogorman PA, Maher N. More extreme precipitation in the world’s dry and wet regions. Nat Clim Change. 2016;6(5):508–513. 35. Tippett MK, Lepore C, Cohen JE. More tornadoes in the most extreme U.S. tornado outbreaks. Science. 2016;354(6318):1419–1423. 36. Vitousek S, Barnard PL, Fletcher CH, Frazer N, Erikson L, Storlazzi CD. Doubling of coastal flooding frequency within decades due to sea-level rise. Sci Rep. 2017;7(1):1399. 37. Iqbal S, Clower JH, Hernandez SA, Damon SA, Yip FY. A review of disaster-related carbon monoxide poisoning: surveillance, epidemiology, and opportunities for prevention. Am J Public Health. 2012;102(10):1957–1963. 38. Bell JE, Herring SC, Jantarasami L, et al. Impacts of extreme events on human health. In: Crimmins A, Balbus J, Gamble JL, et al., eds. The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment. Washington, DC: U.S. Global Change Research Program; 2016:99–128. 39. Ryan B, Franklin RC, Burkle FM Jr., et al. Identifying and describing the impact of cyclone, storm and flood related disasters on treatment management, care and exacerbations of non-communicable diseases and the implications for public health. PLoS Curr Disast. 2015;7. 40.

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41. Balmes JR. Where there’s wildfire, there’s smoke. M Engl J Med. 2018;378(10):881–883. 42. Stanke C, Kerac M, Prudhomme C, Medlock J, Murray V. Health effects of drought: a systematic review of the evidence. PLoS Currents Disasters. 2013;5. 43. Abbas M, Aloudat T, Bartolomei J, et al. Migrant and refugee populations: a public health and policy perspective on a continuing global crisis. Antimicrob Resist Infect Control. 2018;7:113. 44. Neria Y, Galea S, Norris FH. Mental Health and Disasters. New York, NY: Cambridge University Press; 2009. 45. Fann N, Brennan T, Dolwick P, et al. Air quality impacts. In: Crimmins A, Balbus J, Gamble JL, et al., eds. The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment. Washington, DC: U.S. Global Climate Research Program; 2016:69–98. 46. Fiore AM, Naik V, Leibensperger EM. Air quality and climate connections. J Air Waste Manag Assoc. 2015;65(6):645–685. 47. Harvey BJ. Human-caused climate change is now a key driver of forest fire activity in the western United States. Proc Natl Acad Sci. 2016;113(42):11649–11650. 48.

Reid CE, Brauer M, Johnston F, Jerrett M, Balmes JR, Elliott CT. Critical review of health impacts of wildfire smoke exposure. Environ Health Perspect. 2016;124(9):1334–1343.

49. Zhang Y, Bielory L, Mi Z, Cai T, Robock A, Georgopoulos P. Allergenic pollen season variations in the past two decades under changing climate in the United States. Glob Chang Biol. 2015;21(4):1581–1589.

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50. Ziska L, Knowlton K, Rogers C, et al. Recent warming by latitude associated with increased length of ragweed pollen season in central North America. Proc Natl Acad Sci U S A. 2011;108(10):4248–4251. 51. Ziska LH, Makra L, Harry SK, et al. Temperature-related changes in airborne allergenic pollen abundance and seasonality across the northern hemisphere: a retrospective data analysis. Lancet Planet Health. 2019;3(3):e124–e131. 52. Ziska LH, Beggs PJ. Anthropogenic climate change and allergen exposure: the role of plant biology. J Allergy Clin Immunol. 2012;129(1):27–32. 53. D’Amato G, Pawankar R, Vitale C, et al. Climate change and air pollution: effects on respiratory allergy. Allergy Asthma Immunol Res. 2016;8(5):391–395. 54. Sheffield PE, Weinberger KR, Kinney PL. Climate change, aeroallergens, and pediatric allergic disease. Mt Sinai J Med. 2011;78(1):78–84. 55. Altizer S, Ostfeld RS, Johnson PT, Kutz S, Harvell CD. Climate change and infectious diseases: from evidence to a predictive framework. Science. 2013;341(6145):514–519. 56. Beard CB, Eisen RJ, Barker CM, et al. Vector-borne diseases. In: Crimmins A, Balbus J, Gamble JL, et al., eds. The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment. Washington, DC: U.S. Global Climate Research Program; 2016:129–156. 57.

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85. Rehm CD, Monsivais P, Drewnowski A. Relation between diet cost and Healthy Eating Index 2010 scores among adults in the United States 2007–2010. Prev Med. 2015;73:70–75. 86. McLeman RA. Climate and Human Migration: Past Experiences, Future Challenges. New York, NY: Cambridge University Press; 2014. 87. McAdam J, ed. Climate Change and Displacement: Multidisciplinary Perspectives. Oxford, UK: Hart Publishing; 2010. 88. Koslov L. The case for retreat. Public Cult. 2016;28(2 79):359–387. 89. Dannenberg AL, Frumkin H, Hess JJ, Ebi KL. Managed retreat as a strategy for climate change adaptation in small communities: public health implications. Clim Change. 2019. 90.

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11 Happiness on a Healthier Planet John F. Helliwell and Jon Hall

Is planetary health linked to a satisfying life characterized by happiness and wellbeing? This would be a very good thing, as it would represent a double victory, with both people and the planet better off. And the positive narrative of a better, happier future might help propel the transition to a sustainable planet. People are drawn far more to the promise of fulfilling lives than to the grim prospect of deprivation and sacrifice. In this chapter we sketch a number of links between happiness and planetary health, some direct and others indirect. First, a society focused on increasing its happiness will have a smaller environmental footprint than one focused on increasing its economic output, because some of the key determinants of happiness draw little or nothing from the planet’s carrying capacity. Second, happier people are healthier, both mentally and physically, and healthier people are happier. Many causal pathways contribute to this virtuous cycle. Third, when societies are happier they are better able to cooperate to tackle pressing environmental problems. Humanity has been thinking about wellbeing and happiness for a long time and in different ways. The Buddha and Aristotle were among the early happiness philosophers. The Buddha’s thinking on achieving happiness (which he framed in terms of escaping suffering) is summarized in the Four Noble Truths and the Noble Eightfold Path. He believed that people look for sensual pleasures, possessions, and attachments. The impermanency of such goals, he argued, inevitably lead to unhappiness, from the disappointment of Any views expressed in this chapter are of the authors and do not represent views of the United Nations Development Programme, the Human Development Report Office, or any other organization, agency, or programme of the United Nations.

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loss and envy of others.1 Aristotle had a different viewpoint, arguing that humans are social animals, with individual happiness secured only within a political community, or polis. The polis should organize itself to promote virtuous behavior. As in Buddhist teaching, virtue is conducive not only to individual wellbeing but also to social harmony.1 Both these strands of early teaching resonate in current wellbeing research and underlie the compatibility between happiness and planetary health. But before considering these links, we need to define some terms and clarify how happiness is measured in modern research.

Defining and Measuring Happiness Defining Terms: Wellbeing, Subjective Wellbeing, and Happiness The concepts of happiness and wellbeing are closely related. Wellbeing is often taken to refer to all aspects of human existence (economic, social, emotional, and physical). Happiness, in contrast, focuses on how people feel, which is why it is often more formally described as “subjective wellbeing.” There are three main types of happiness measures: measures of positive emotions (positive affect), measures of negative emotions (negative affect), and evaluations of life as a whole.2 Happiness is often used to describe both measures of positive affect and life evaluation. The same word is therefore used to describe two different things: happiness as an emotion (“Are you happy now?”), reflecting a person’s mood, and happiness as a life assessment (“Are you happy with your life as a whole these days?”), reflecting a cognitive judgment. This distinction is variously described as hedonic versus eudaimonic3 or as the accumulation of net momentary pleasures versus a life full of meaning and good purpose.4 The two meanings bring a risk of confusion, because people might assume that all happiness measures are equivalent, although the evidence is increasingly clear that these two different ways of measuring happiness are distinct in ways that support the credibility of both. We argue below that life evaluations provide an umbrella measure of subjective wellbeing, broad enough to encompass the effects of positive emotions, good health, income, friendship, and virtue in the Aristotelian and Buddhist senses.

Beyond the Gross Domestic Product “What we measure affects what we do,” wrote renowned economists Joseph Stiglitz, Amartya Sen, and Jean-Paul Fitoussi. “If we have the wrong metrics, we will strive for the wrong things. In the quest to increase GDP, we may end up with a society in which most citizens have become worse off.”5 In pursuing societal goals such as happiness, health, and environmental sustainability, it is critical to use the right performance metrics because the way we measure success shapes our actions.

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The most widely used measure of societal performance is the gross domestic product (GDP), the total market value of a country’s output (all the goods and services produced) over a defined time period. But this measure has numerous shortcomings, which have long been recognized. Simon Kuznets, one of the fathers of the system of national accounts, showed remarkable prescience, writing nearly a century ago that “the welfare of a nation can scarcely be inferred from a measurement of national income.”6 More recently, the French Commission on the Measurement of Economic Performance and Societal Progress pointed to both the limitations of GDP as a metric of wellbeing and the dangers of using it in that way.5 The limits of the GDP are explored in detail in Chapter 15. Could social metrics be more people centered, shifting the focus from economic activity toward human wellbeing? One step in this direction came in 1972, when King Jigme Singye Wanchuk of Bhutan said that gross national happiness is more important than gross national product. In the intervening years, Bhutan has continued to make gross national happiness the focus of its internal policymaking and inspired global efforts through a series of gross national happiness conferences (Figure 11.1). In June 2011, the United Nations General Assembly passed a resolution, introduced by Bhutan, inviting

Figure 11.1 An elderly woman and a baby in Bhutan. Source: Photo by Jon Hall

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member countries to measure the happiness of their people and to use these measures to help guide their public policies. This was followed, in April 2012, by a UN high-level meeting on happiness and wellbeing, chaired by the prime minister of Bhutan. The first World Happiness Report was prepared for and released at that conference. Its purpose was to review available data and scientific research and to support national efforts to understand and use happiness as a policy tool. Interest generated by the UN meeting was sufficient to lead to subsequent World Happiness Reports, now released annually on March 20, World Happiness Day, by the UN Sustainable Development Solutions Network. Drawing heavily on data from the Gallup World Poll, each report ranks national happiness based on the three most recent years of answers to a life evaluation question posed to roughly 1,000 people per year in each of more than 150 countries. The annual data are used to probe differences in happiness, both across countries and over time, in term of six key variables: healthy life expectancy, GDP per capita, having someone to count on in times of need, generosity, trust (as measured by the absence of corruption), and a sense of freedom to make key life decisions. Because the last four variables contribute so importantly to happiness, and because they entail much less use of material resources than required by a typical increase of GDP, a shift from income to happiness as the measure of progress would immediately lessen the link between human progress and material consumption. This would obviously be beneficial for planetary health.

A Multidimensional Index or a Single Measure? Most people would agree that wellbeing is multidimensional, in the sense of depending on many different things, but there are many views on what those dimensions are and how they should be defined. Even if consensus can be reached on what the contributors to wellbeing are and how each should be measured, the resulting dashboard of indicators, which might include such measures as health, education, income, crime, and air quality, does not lend itself readily to political decision making or public debate. One reason for the continued use of GDP as a progress indicator is that it is just one number. It is much easier to interpret changes in GDP (with an increase seen as good and a decrease as bad), or to rank countries according to their GDP, than to summarize changes in a multitude of separate indicators that might be moving in different directions. This suggests that any competing candidate for policy attention should also share GDP’s features of being a single indicator, providing a more compelling focus for public attention. What number might serve that purpose? The most widely known approach is a composite indicator, which aggregates the various dimensions of wellbeing into a single

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number. The UN Development Programme’s Human Development Index, for example, combines life expectancy, education, and per capita income. But composite indicators remain open to criticism because they must use arbitrary weighting to combine the component indicators, which are usually measured in different units, such as life expectancy (in years), income (in purchasing power), and air pollution (in particles per volume of air). Combining these units poses a fundamental methodological (and ethical) problem: Any composite indicator is based on some judgment about the relative weights to be applied to the components. And there is a danger that political discussion will focus more on the choice of weights than on the overall indicator, thereby generating more heat than light in the attempt to quantify wellbeing.7 A solution to this dilemma is to use a single measure: subjective life evaluations. People’s ratings of their own wellbeing are unvarnished measures of what people actually think about the quality of their lives. Box 11.1 presents some reasons why self-assessments might be better than an index as an overall measure of wellbeing.

Subjective Wellbeing: A Valid Measure So subjective assessments of wellbeing have conceptual strength. But can happiness be meaningfully quantified? Does the ambiguity of the word happiness, discussed above, impede valid measurement? Fortunately, respondents to surveys know the difference between being asked about their happiness right now (their emotions) and being asked about their happiness with the overall course of their lives. Survey answers show that people recognize the context in which the question is being asked and answer appropriately. When asked about their happiness yesterday, people in the Gallup U.S. Poll report having been happier on weekend days than on weekdays.8 Furthermore, research on large samples of these answers show that these weekend boosts in happiness depend on the quality of people’s social lives both on and off the job. Those who think of their immediate superior at work as a partner, rather than a boss, have weekdays just as happy as their weekends. Their emotional responses thus vary from day to day depending on the quality of their lives that day.9 Questions asking people how satisfied they are, or how happy they are, with their lives as a whole elicit the same answers whether they are asked on weekdays or weekends. This is just what philosophers would argue should be the case. People recognize that the meaning of the word happiness depends on the conversational context, giving an emotional answer when that is asked for and an evaluative one when that is appropriate. As the World Happiness Reports have shown, national average answers to questions about emotions are determined by different factors than answers about life evaluation. There is a hierarchy of a sort predicted by Aristotle; positive emotions are just one predictor

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Box 11.1. Six Conceptual Advantages of Subjective Self-Assessment over Composite Measures of Wellbeing • One can attach fundamental importance to the evaluations people make of their own lives. This gives them a reality and power that no expertconstructed index could ever have. For any measure that strives for objectivity, it is crucial that the rankings depend entirely on the basic data collected from population-based samples of individuals, not on what experts think might or should influence the quality of their lives. • Life evaluations represent primary facts about the value people attach to their lives. This means one can use the data as a basis for research designed to show what helps to support better lives. • The fact that the data come from population-based samples allows one to calculate and present confidence intervals about the estimates. • Any index depends (to an unknown extent) on the index makers’ opinions about what is important. This uncertainty makes it hard to treat an index as an overall measure of wellbeing or even to work out the extent to which variations in individual components affect overall scores. Even where this decomposition is done, there is no way of establishing its validity, because the index itself is just the sum of its parts, not an independent measure of wellbeing. • Measures of subjective wellbeing, and especially life evaluations, or judgments by individuals about how happy they are with their lives as a whole, can be treated as encompassing social indicators. Only life evaluations, among all the variety of social indicators, meet the two primary tests for an encompassing measure. First, they have good claims to be themselves global assessments of the quality of life, without any further construction or manipulation. Second, because they are primary measures and also encompassing in their scope, they provide the research base for answering the fundamental quality of life question: What tends to lead to a better life, as seen by those doing the living? • Subjective wellbeing is measured at the individual level and hence can be averaged over any selected area or segment of the population, something not possible with aggregate measures.

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of a higher life evaluation, alongside other factors such as good health and sufficiency of material supports. Although short-term positive emotions are certainly a part of a good life, the hierarchical relation between emotions and life evaluations makes the latter more suitable as an encompassing measure of wellbeing.

Happiness and Planetary Health How might shifting policy attention from specific material goals to wellbeing more generally, and especially to happiness, help to improve planetary health? There are at least three direct and two indirect pathways. First, the main supports for happiness require fewer scarce planetary resources than do many types of economic growth, promoting the planetary side of planetary health. Second, happiness is a source of good physical and mental health, and vice versa, promoting the human health side of planetary health. Moreover, these positive linkages are good not only for human health but also for the health of ecosystems: Promoting happiness is a less resource-intensive way to promote health than treating an illness once it occurs. Third, because healthy ecosystems are important to human happiness, societies that pay more attention to happiness as a goal will want to pay greater attention to environmental protection, promoting both the human and the planetary sides of planetary health. Indirect pathways from happiness to planetary health are also important. There are at least two. First, happiness is both a cause and a consequence of prosocial norms and behaviors, which can in turn support social identities that extend caring across countries, other species, and other generations, all important ingredients of planetary health. Moreover, trust provides a social glue that keeps people working together for a bigger cause such as planetary health, which itself is an important source of happiness beyond its role in fueling social progress. A second indirect benefit is that happiness research is unlocking better policies in specific areas relating to planetary health, such as how social services are delivered.

Happiness Production Is Not Resource-Intensive It is widely recognized that social relations are the cornerstone of happy lives. But it is less often appreciated that social relations—and several other vital supports for happiness—typically require little or nothing by way of material and energy resources, whose increasing use is threatening the planet’s sustainability. The Gallup World Poll data, reported in successive World Happiness Reports, show that emotions, whether positive or negative, depend little on the material aspects of life; social factors are far more important.* The same is true of life evaluations, which vary between *Of course, for societies plagued by poverty, instability, and conflict, achieving a minimum level of prosperity and stability is an important foundation of happiness.

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individuals and across nations based on six factors. Four factors account for more than half of the explained differences: having someone to count on, generosity, freedom to make life choices, and absence of corruption. These draw little or nothing from the planet’s carrying capacity. Two other factors, income and health, account for the balance of explained differences; although these both draw on material inputs, they also depend importantly on social context. Predictors of happiness vary between the individual and aggregate levels. The main difference is that at the national level, the effect of social factors rises relative to the effect of income. The reason for this is that an important part of the psychological gains from income are derived from relative income effects (“keeping up with the Joneses”), and these gains disappear when all incomes rise together. By contrast, people are happy if they themselves are more trusting and have a strong sense of belonging, and they are even happier when others feel the same way. Put simply, there is a negative happiness effect from other peoples’ material consumption but not from their trust, good health, or most other nonmaterial supports for wellbeing. Shifting emphasis to the importance of the social context of life—how people support and value each other, whether within or across communities, countries, and generations—thus lowers the energy and material footprint of national progress.

Happiness and Human Health Are Intertwined Human health is central to planetary health. In this context, it is important to understand the strong links between happiness and human health. Both mental and physical health are key determinants of people’s happiness.10 This association operates in both directions; studies have also shown that happiness contributes to good health.11–14 Some of this benefit is mediated by behavioral choices; happy people tend to eat healthier diets and exercise more frequently than do unhappy people.15,16 But there are fascinating direct biological pathways as well. Levels of happiness influence the body’s ability to avoid or recover from many conditions, from the common cold to more serious ailments. For example, positive emotions are associated with enhanced immune responses to infection,17,18 whereas adversity and stress in childhood predict elevated markers of inflammation a few years later, which in turn can signal cardiovascular risk.19,20 And so, other things equal, happier people also enjoy healthier, longer lives.

Natural Environments Make People Happy Let us imagine you are a politician, perhaps a mayor, convinced of the need for policies that increase citizens’ happiness. There are at least six policy spaces within which you can work to achieve that goal: the economy, education, health, society and culture, government services and governance, and environment and infrastructure. We focus here on environment and infrastructure.

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Both the built and natural environment can contribute substantially to happiness. For example, access to green space within urban environments, a topic explored further in Chapter 13, can directly boost people’s happiness (Figure 11.2). In one study, people assigned to walk along a tree-lined riverside path in Ottawa were happier than those who walked between the same two points via an underground tunnel system, and the gains in happiness were much higher than participants expected.21 In another study, more than 20,000 participants were prompted at random moments during the day by a smartphone app and asked to rate their level of happiness. Their responses were correlated with the land cover type (e.g., woodland, grassland, urban) of their location at the time they responded. People were substantially happier when outdoors in green or natural habitat types than when indoors or in continuous urban settings.22 Similar findings have been reported in many other studies.23 Perhaps more importantly, long-term nature contact is associated with increased life satisfaction (corresponding to the idea of subjective well-being discussed above). A survey of 18,441 people in 281 cities across China revealed an association between life satisfaction and the extent of the city’s vegetative cover (and a negative association with levels of air pollution),24 results that replicated earlier findings in Australia,25,26 Japan,27 and the

Figure 11.2 Social bonds with family and friends, and contact with nature, both predict happiness. Source: Photo by Jove Duero (Unsplash)

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United Kingdom.28 People who report feeling more connected with nature also report being happier.29 The links between nature contact and happiness may operate not only directly but also indirectly by boosting social connectedness, a benefit observed in neighborhoods and parks.30–32 Social connectedness, in turn, promotes both happiness and health. Much of the available evidence linking nature contact and health comes from urban settings, where more than half the world’s population lives. But the largest expanses of nature are outside cities and towns. Could the conservation of large ecosystems contribute to human happiness, and could a greater emphasis on happiness contribute to saving such places? Two lines of thinking suggest that the answer is yes. First, rural areas are home to many people, especially Indigenous communities, around the world (Figure 11.3). The impact of protecting these environments would be significant for both for happiness and many aspects of planetary health. For instance, Indigenous peoples own or inhabit massive ecosystems in several countries. Indigenous land holdings in Australia cover one fifth of the country, and in Canada, twenty-nine comprehensive land claim or self-government agreements, in almost all cases including extensive resource management provisions and covering more than 40% of Canada’s land mass, have been ratified and brought into effect over the past 40 years.33 Although studies

Figure 11.3 Indigenous village of the Kogi in the mountains of the Sierra Nevada de Santa Marta in Colombia. Source: Shutterstock

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are few, it seems reasonable to believe that conservation of natural places would yield particularly profound benefits for the happiness of Indigenous peoples, given the close bonds—economical, spiritual, and cultural—many have with the land and sea. For example, researchers at Australian National University found that “living on one’s homelands or traditional country and undertaking harvesting activities was found to be associated with a higher level of self-reported happiness for Indigenous Australians.”34 Second, beyond these direct links, biodiversity and ecosystems have, for at least some people, an existence value, the benefit people receive from knowing that something exists.35 The value stems from the pleasure you or I may get from knowing that African elephants still roam the Serengeti or that the Amazon rainforest survives, even if we will never see them for ourselves. The strength of this value doubtless varies significantly, but it is well established (and was used in the legal assessment of damages after the Exxon Valdez oil spill in 1989, for example).36 These direct and indirect pathways from natural environments to human happiness are sometimes called cultural ecosystem services.37,38 It seems reasonable to speculate that if nations get serious about improving life evaluations among their citizens, they will soon after pay greater attention to such services—to the more-than-economic benefits provided by the natural environment. Moreover, they will consider a wider set of benefits than those that normally feature in the policymaker’s calculus. And this would be good for planetary health. If you care about happiness, you should care about the environment.

Prosocial Behavior, Happiness, and Trust Prosocial behavior is kind or generous behavior intended to help others. In this section we first explore evidence of the links between prosocial behavior and happiness. Next, we show how these two attributes, together with a third, trust, are linked in the creation of broader social identities—identities that promote pro-environmental policies and behavior while increasing happiness. A starting point is the fact that humans are prosocial beings. This may not be self-evident; a dominant and pervasive narrative, grounded in classic philosophical theories and economic models, suggests that humans are cold, calculating, and selfish. But a large and growing body of research challenges this assumption and argues that we are naturally a prosocial species. Young children provide help to others, even strangers, and are willing to do so both spontaneously and anonymously (Figure 11.4). Indeed, young children show signs of physiological arousal when seeing others in need, and this state is calmed when the child or a third party can assist. Importantly, prosocial tendencies appear before several signs of high-level executive control, suggesting that prosocial acts are not premeditated to facilitate future gains but instead reflect a genuine interest in the wellbeing of others.39,40 Well beyond childhood, adults routinely engage in prosocial behavior. Each year, people donate billions of dollars to charitable organizations and volunteer countless hours

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Figure 11.4 Prosocial behavior develops early in children. Source: Shutterstock

to helping others in need. In addition, people give of themselves physically by donating blood and organs. Such generosity is not limited to high-income countries and can be seen across a wide span of human cultures from around the world. Consistent with the developmental evidence reported above, adults’ prosocial action may reflect an intuitive or automatic response. For instance, in some experiments people forced to make fast economic decisions (in less than 10 seconds) were more generous than people forced to make slow economic decisions (in more than 10 seconds), especially if they are prosocially oriented people.41 This may help explain why some people are willing to pay more money to decrease harm to a stranger than they are to decrease harm to themselves. Not only are people prosocial beings, but prosocial behavior makes people happy. Toddlers under the age of 2 given edible treats and asked to share their resources with others smiled more when giving treats away than when receiving treats themselves. Moreover, their smiles were rated as significantly larger when they were giving away their own treat (that is, when engaging in costly giving) than when giving away an identical treat that was provided by the experimenter (that is, when engaging in noncostly giving), suggesting not only that giving is rewarding for young children but that it may be especially rewarding

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when costly.42 Among adults, people donating money to charity or making a public pledge to donate in the near future show greater activation in areas of the brain typically associated with reward processing than those receiving various forms of self-benefit.43 Similarly, participants randomly assigned to spend money on others report higher levels of happiness afterward than those randomly assigned to spend money on themselves, a finding that has been replicated in rich and poor countries around the world.44 Large data sets tell a similar story. Mirroring the importance of social connections for wellbeing, data from the Gallup World Poll indicate that giving to others (measured as donations to charity in the last month) is one of the six main predictors of life satisfaction around the globe.45 It isn’t just the act of giving that makes people happy. Prosocial behaviors also come with positive externalities, or spillovers. In other words, if you live in a community with high levels of volunteering, even if you do not volunteer, your subjective wellbeing will still tend to be increased by all that goodwill around you, and greater strength of local social norms is likely to increase your own future generosity. Whereas anger may beget anger, kindness triggers future benevolence. So, happiness and prosocial behavior reinforce each other.46 Another attribute, trust, is closely related to both prosocial behavior and happiness. In fact, a virtuous circle links them all. People who believe that others are trustworthy are happier, are more likely to cooperate with each other, and are substantially protected against the loss of happiness that otherwise comes with unemployment, ill health, and discrimination.47 High trust itself has been associated with good physical health,48 and decades of experiments and field trials have shown that those with closer social connections are more likely to trust others and to develop cooperative solutions for using and preserving scarce planetary resources.49 Societies with higher trust and positive social connections are happier places in which to live. And, in the other direction, people living in happier societies are more likely to behave in prosocial ways. Interestingly, people often underestimate the level of trustworthiness in their communities. Figure 11.5 shows survey data results from the Statistics Canada General Social Survey in Toronto. Respondents were asked to assess the probability that a lost wallet (containing $200) would be returned if found by a neighbor (the left bar) or by a stranger (the middle bar). The Toronto Star then conducted an experiment by dropping twenty cash-containing wallets on streets; the result is shown on the bar on the right.50 Strangers were significantly more trustworthy than people expected. Recent research shows that these experimental results are also applicable in a global context. The Gallup World Poll asked people in 132 countries how likely return of their lost wallets containing valuables would be if the wallet were found by a stranger. A recent experiment in forty countries asked people to return wallets to fictional owners.51 Our subsequent research comparing

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Figure 11.5 Survey estimates of trustworthiness (the probability of a lost wallet being returned) versus the observed probability that a lost wallet is returned. Source: John Helliwell

the Gallup and experimental data for wallets containing money shows that international differences in the rate of actual wallet return are highly correlated with expected wallet return (+0.83) across the 16 countries in both samples, and the average actual rate of return is significantly higher than expected (42% compared with 20%). If people are inherently prosocial, and if prosocial behavior increases happiness and trust, can prosocial behavior be encouraged? Examples from around the world suggest that the answer is yes. Campaigns successfully increase blood and charity donations, and tax breaks successfully encourage people to give more. Other campaigns have targeted environmental behavior, such as a cleanup campaign that removed 5.3 million kilograms of rubbish from a Mumbai beach in less than 2 years.52 But there is much to be discovered. The Mumbai campaign raises a final question: How might a more prosocial society benefit planetary health?

Harnessing Prosocial Behavior to Build Happiness and Planetary Health Many of the most pressing environmental concerns today involve protecting commonpool resources (e.g., fish stocks or forests). These may be national, regional, or global in scope. Economists understand that such goods suffer from classic free-rider problems,

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a market failure that occurs when people take advantage of using a common resource or collective good without paying for it.53 Such problems occur when people, either as individuals or in corporations, behave individualistically and consider only the costs and benefits that directly affect themselves, without considering their impact on others or on the sustainability of the common pool resource. My choice to spend the weekend fishing may fill my freezer, but it will reduce what is available for my neighbors to catch and even perhaps reduce the long-term sustainability of the fishery. There are numerous potential solutions to free-rider problems. Conventional environmental economic policymakers often find themselves arguing about and choosing between taxes, regulations, subsidies, and tradable pollution permits and the level and structure of utility prices. Although these tools, especially those that enable users to know the overall social and environmental costs of the resources they are consuming, are an essential part of the story, they are based on the idea of Homo economicus, the premise that people are largely interested in themselves rather than others. Indeed, it is these behaviors that lead to free-rider problems in the first place. But these tools fail to exploit the power of social norms to create better solutions. Yes, people, companies, and communities show self-interest sometimes. But they also exhibit reciprocity in the right circumstances. Even more importantly, empathy and generosity can fuel behavior that benefits people in distant lands and far-future generations, well beyond the boundaries of communities linked by reciprocity. And the fact that such behaviors promote happiness suggests that they can be readily promoted. As our understanding of planetary systems grows and as attitudes change, the possibility of creating and harnessing new environmental norms grows. This means there are other ways to approach environmental degradation, especially if enough people in a society do not behave—or do not want to behave—as free-riders. This may be because they learn that prosocial behavior makes them happy or because they come to adopt more prosocial (and pro-environmental) norms. As we have argued, subjective wellbeing rises when people are offered and accept the opportunity to do things for others. Actions to improve local and global environments for the benefits of others in current—and very importantly future—generations fall right into that sweet spot. As political scientist Elinor Ostrom and her co-authors argued in 1999, “reciprocal cooperation can be established, sustain itself, and even grow if the proportion of those who always act in a narrow, self-interested manner is initially not too high.”54 People enjoy doing things with and for others, and under the right circumstances they are willing to subsume their own personal interests for the sake of a broader shared purpose. What are the conditions necessary to harness this potential to support planetary health? Although it may be useful to seek national or global consensus or guidelines, local circumstances matter greatly. Evidence suggests that people are happier acting in

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prosocial ways if the choice is theirs and if they are neither coerced nor offered payment to do so. They are also happier if and when they are convinced that their actions serve a good purpose.55 Prosocial actions can happen anywhere. Virtuous circles can be started as simply as through random acts of picking up sidewalk litter. For the benefits of these activities to spread more widely, and to create broader prosocial norms, we need more systematic evidence that such actions work, and we need wide distribution of compelling, effective narratives. In settings where self-interest is considered normal or even desirable, even more evidence of the prevalence and power of prosocial actions may be needed. Simply persuading people’s conscious minds to accept what their unconscious might already know is an important first step, because people appear to underestimate systematically the positive impact that giving will have on themselves and others. This was powerfully illustrated in an experiment in which people were given $20 and randomly asked to spend it on themselves or someone else. When asked to predict which of the two options would make them feel happier, most people predicted that it would be spending on themselves. In fact, the opposite was true.56 The “Green Gyms” initiative of the South Tyneside Metropolitan Borough Council in northeast England, centered in the most deprived wards of the borough, provides a good example.57 These community-led projects include allotment development, nature reserve conservation, and restoration of community gardens and public open spaces. Similarly inspired neighborhood gardens are starting to appear, or reappear, in urban areas throughout the world.58 These activities require leadership and supporting social norms to get started, but the individual and community-level rewards they provide—ending or reducing social isolation, building connections that increase both current wellbeing and community capacity, increasing physical activity, and promoting pro-environmental attitudes—are likely to make them self-sustaining.59,60 With luck they provide beacons for others to adopt and improve. To broaden social norms to apply more broadly over space and time, as needed to address major global challenges such as CO2 emissions, will require altruism and trust that extend beyond the borders of one’s own country (let alone community) and to future generations. This is likely to be more difficult for many reasons, not least because evidence suggests that groups of people who can identify one another are more likely than strangers (in Ostrom’s words) to “draw on trust, reciprocity and reputation”54 to develop norms that limit resource use.61 There are also concomitant challenges, which Ostrom describes, of cultural diversity. Diversity may bring more ideas about how to solve problems, but cultural diversity can increase the complexity of finding shared interests and understandings.61 In earlier generations this complexity limited the size and diversity of groups that could cooperate. But

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now the Internet and social media can enable large numbers of people to connect with one another and to learn more easily what works and what does not work in the search for sustainable futures. That said, these same technologies provide an equally powerful tool for those bent on spreading suspicion, hate, and distrust. The net social and environmental effects of these technological changes thus remain in question. What is certain is the need for broader social identities, solidarity, and shared values to provide a basis for long-term planetary health to become a central value for individual and collective human behavior. These shared social identities and values themselves build life satisfaction, as we have shown. The needed transformation may not happen overnight, but a fundamental first step is appealing to humanity’s inherent prosociality. Unlocking that requires empowering people while recognizing that people are more likely to develop prosocial and environmentally responsible norms under governments that, in Ostrom’s words,54 “facilitate their efforts [rather] than in regimes that ignore resource problems entirely or that presume that central authorities must make all decisions.” It is also useful to abandon, or at least sideline, fatalism in the interests of developing more productive, optimistic, and realistic views about the motives and behavior of others. We are struck by evidence that even in the more trusting and happier countries there are prevailing and falsely pessimistic beliefs about the goodwill and prosocial behavior of their fellow citizens. Social norms, especially where they are supported by broader social identities that encompass global populations and future generations, can play a vital role in sustaining the planet’s health. By creating a wider sphere of empathy—a larger “us”—these broad social identities can help bridge what might otherwise be cleavages that result in conflict and selfish behavior and threaten both the human and environmental aspects of planetary health.

Changing How Policies Are Designed and Delivered The ways in which public and private services are designed and delivered matter. Inclusive community involvement fosters social norms that favor the long term over the short, the future over the present, and others over the self. Collaboratively designed and delivered services yield happier lives for both providers and recipients of the services. In 2004, for instance, the government of Singapore introduced a “No Wrong Door” (NWD) initiative designed to ensure that every request for information or services from a government employee would trigger best efforts either to deal directly with the request or to find someone who can help. This government-wide policy aimed to redesign the social relationships between citizens and their government by changing the “how” rather than just the “what” of public services. The purpose was no doubt to increase the quality of life for citizens.62

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NWD policies have subsequently been implemented in many places, from Durham, Ontario (for children and youth services) to Sydney, Australia (for mental health services) to the state of Virginia (for senior services). Few such initiatives have been rigorously evaluated; an exception was a youth services program in North Yorkshire (in the United Kingdom).63 The evaluation, 2 years into the program, revealed significant improvements in overall scores on the Strength and Difficulties Questionnaire, which screens for behavioral and emotional problems in children and youth. Central to this and other successful applications of the NWD policy are more collaborative and forward-looking linkages between government departments and agencies. The effects of this closer cooperation on the happiness of the care workers are probably positive but remain to be properly evaluated. Similarly, although the children and families kept out of trouble and treatment by these early positive interventions almost surely have happier lives as a consequence, these effects are still unstudied. The lessons gradually emerging here could surely translate into human services policy more generally and, beyond that, into many other policies aimed at caring for the planet’s health. Although evidence is scant, it seems entirely reasonable to assume that citizens and businesses will be more likely to offset or reduce their carbon emissions, dispose responsibly of toxic waste, or follow any environmental directive if the process is straightforwardly effective and they are treated with respect, courtesy, and even friendliness.

Conclusion Happiness ought to be a central measure of a society’s progress, because it would promote planetary health through a variety of routes. Some of these gains are direct and well understood: Societies focused on growing happiness instead of GDP would focus less on consuming energy and materials, and happier people are generally healthier. Some mechanisms are indirect and as yet untested in policy applications. But there is a wealth of experimental evidence that a happier, more prosocial citizenry would have—or develop— the encompassing social identities, with their matching trust networks, needed to build planetary health and tackle formidable planetary challenges.

Authors John Helliwell, DPhil is with the Vancouver School of Economics at the University of British Columbia. Since finding out some 25 years ago about the availability and validity of people’s evaluations of their own lives, he sees himself as Aristotle’s research assistant, using these life evaluations to explore what makes for better lives, especially the social context. He has since 2012 been co-editor of the now annual World Happiness Reports, published by the United Nations Sustainable Development Solutions Network.

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Jon Hall, MS works for the United Nations Development Programme in New York. He has also worked for the British and Australian governments and the OECD. He’s spent the past 20 years trying to encourage societies around the world to have broader conversations about national progress in ways that go beyond economic growth to encompass sustainable wellbeing.

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Part 3 Pivoting from Threat to Opportunity

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12 Energy and Planetary Health Ajay Pillarisetti and Kirk R. Smith

Humanity cannot thrive without universal access to energy. Basic needs (such as producing and preparing food and heating homes) and more modern concerns (including communications, manufacturing, and transportation) depend on access to energy. As with the design of food production systems, urban environments, and businesses and industries, choices made about energy sources are now understood to be pivotal for planetary health. Today, these choices are driving two enormous planetary health challenges, air pollution and global climate disruption, while inadequate access to clean energy is still an urgent problem for more than a billion people. But careful choices could bring a very different future than the one that now seems imminent, a future in which every person has access to clean, reliable energy and where a postcombustion energy system no longer produces greenhouse gases that fuel climate change or the air pollution that claims millions of lives annually. Although energy supports healthy communities and enhances livelihoods, all forms of energy use have negative consequences for health and the environment to different degrees. Figure 12.1 shows major linkages between energy and health. It separates fuels and their processing from intermediate energy forms, such as electricity, and highlights various end-use energy services, such as lighting and transportation. There are potential implications for health at each stage of this conceptual pathway. The current global energy landscape relies heavily on the combustion of fossil fuels, including coal, petroleum, and natural gas, for electricity generation and transportation. Between 1973 and 2016, total energy consumption more than doubled.1 Although the fraction generated by renewable sources—including geothermal, solar, wind, and

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Figure 12.1 A conceptual pathway linking energy use and health. Sources: Updated, revised, and adapted from Jaccard M. Sustainable Fossil Fuels: The Unusual Suspect in the Quest for Clean and Enduring Energy. Cambridge, UK: Cambridge University Press; 2005; and Wilkinson P, Smith KR, Joffe M, Haines A. A global perspective on energy: health effects and injustices. Lancet 2007;370(9591):965–978.

hydropower—increased dramatically over the same time period, renewables still represent a small fraction of total consumption, approximately 4%.1 This provides tremendous opportunity for continued growth of clean energy and perhaps equally tremendous peril in the form of continued reliance on fossil fuels, which pose a significant risk to both the environment and human health. Because burning fossil fuels and biomass drives global climate change and most healthdamaging air pollution, an ideal, aspirational future world would involve little or no fuel

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combustion for energy needs—a so-called postcombustion world.2 This is in stark contrast to the historical and ongoing use of primary fossil energy sources (Figure 12.2). In this aspirational future, energy services would be met through electricity provided renewably with a combination of wind, solar, geothermal, tidal and hydropower, and (potentially) nuclear power and would rely on robust decentralized storage systems to help smooth

Figure 12.2 Primary global energy sources (1800 to 2017). New renewables have appeared in recent decades. Note that biomass energy has remained roughly constant as other forms take larger roles. Wind, solar, and other renewables (including biofuels) are so small at present as to be barely visible but are growing rapidly. Source: Generated from data compiled by and available from Our World in Data (ourworldindata. org/energy-production-and-changing-energy-sources). From Our World in Data: All data prior to the year 1965 are sourced from Smil (2017). All data from 1965 onwards, with the exception of traditional biomass, are sourced from BP Statistical Review. Smil’s estimates of traditional biomass have been used for the full series, with interpolation of annual changes by Our World in Data between reported 5-year increments by Smil. From the BP Statistical Review of World Energy: The primary energy values of nuclear and hydroelectric power generation, as well as electricity from renewable sources, were derived by calculating the equivalent amount of fossil fuel required to generate the same volume of electricity in a thermal power station, assuming a conversion efficiency of 38% (the average for OECD thermal power generation). Fuels used as inputs for conversion technologies (gas-to-liquids, coal-to-liquids and coal-to-gas) are counted as production for the source fuel and the outputs are counted as consumption for the converted fuel.

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demand-related problems. Imagining such an electrified world allows us to consider both the benefits of a postcombustion world from climate and health perspectives and the emergent challenges that may arise (e.g., sufficient energy for manufacturing, vehicle recharging infrastructure, siting of renewable resources, waste and resource management, equitable distribution of benefits, and global grid management). This chapter, which draws on a previous review,3 begins with an overview of energy use and its relationship to three core planetary health challenges: ensuring access to clean energy for all, controlling air pollution, and stopping global climate disruption. It then shifts focus to the implications of fossil fuel, nuclear, and renewable sources of energy, including a discussion of emergent issues related to changing paradigms in energy generation, transmission, and storage. The chapter features two boxes: a case study focused on new policies that address household energy poverty and air pollution in India and a case study of unconventional oil extraction and its impact on health and safety in the United States.

Ensuring Access to Clean Energy for All Today’s energy sources include the range of those found throughout human history, from animal power and biomass to processed biofuels, fossil fuels, and renewables including hydropower, solar, and wind. Access to modern forms of these energy sources enables healthier households and communities, increases economic opportunity and inclusion in markets, and promotes human development.4 In 2015, the United Nations adopted the Sustainable Development Goals (SDGs) as a successor to the Millennium Development Goals (MDGs). Seventeen SDGs, across a breadth of domains including health, water, food, climate, and energy were established. Unlike the MDGs, which did not, in their final form, address energy, SDG 7 explicitly seeks to “ensure access to affordable, reliable, sustainable and modern energy for all” by 2030, with three distinct and ambitious targets: 7.1  Ensuring universal access to affordable, reliable, and modern energy services 7.2  Increasing substantially the share of renewable energy in the global energy mix 7.3  Doubling the global rate of improvement in energy efficiency SDG 7 has tight linkages with a number of other SDGs, including SDG 1 (Poverty and development), 3 (Health and well-being), 5 (Empowering women and girls), 8 (Decent work and economic growth), 13 (Combat climate change), and 15 (Sustainably manage forests and halt land degradation). Indeed, an argument can be made that each SDG is affected by energy5 and choices made about energy sources, which in turn play a role in promoting healthy environments and lifestyles.

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Although the links between energy and development are well accepted,4 pathways for providing reliable, clean, and sustainable energy to the approximately 1.1 billion people without electricity6 and 2.5 billion without access to clean cooking fuels7 remain contentious and will be further complicated by growing populations. Planning future energy access and use trajectories in a world with around 7.8 billion people in 2020 and an estimated 9.8 billion in 20508 requires broad-ranging conversations on far-reaching, multistep pathways toward clean energy for all, within constraints imposed by climate change.

The Impacts of Energy on Health Indoor and Household Air Pollution A defining feature of modern humanity that separated it from our prehuman ancestors was the harnessing and control of fire to cook food between 250,000 and 2 million years ago.9,10 Despite widespread global development in the ensuing period, however, billions of people—mainly in low- and middle-income countries (LMICs) and rural areas—continue to rely on biomass burned in open fires and simple stoves as their primary energy source for cooking and heating (Figure 12.3).7,11,12 As a result, significant concentrations of various pollutants—including particulate matter with an aerodynamic diameter of ≤2.5 or ≤10 microns (PM2.5 and PM10), carbon monoxide (CO), nitrogen dioxide (NO2), polycyclic aromatic hydrocarbons, dioxins, and known carcinogens (see Naeher et al.13 for a review of pollutants released from woodsmoke)—are released into the household environment. According to the 2017 Global Burden of Disease estimate,* this household air pollution (HAP) is the thirteenth leading risk factor contributing to global mortality and is responsible for approximately 1.6 million deaths per year.7,14,15 In terms of healthy years of life lost, measured in disability-adjusted life years (DALYs), HAP was directly responsible for 60 million DALYs (2.4% of the total) in 2017 but also contributed to the impact of ambient air pollution. The Institute for Health Metrics and Evaluation7 estimated that in 2016 approximately 2.5 billion people (33.7% of the global population) relied on unclean solid fuels—including *Global Burden of Disease estimates are generated every year by the Institute for Health Metrics and Evaluation and every few years by the World Health Organization. There is regular variation in the methods and data streams used to generate these numbers, resulting in sometimes dramatic year-to-year changes in estimates of the burden of disease. Therefore, the exact numbers are less consequential than the clear burden of disease associated with exposure to both household and ambient air pollution. Nevertheless, variability in estimates probably results from a number of factors, including changes in background mortality and disease rates and changes in exposure response functions. For a sensitivity analysis investigating drivers of variability in burden of disease estimates, see Kodros et al.14

Figure 12.3 Biomass cookstoves. (a) Traditional biomass cookstove and (b) an advanced semi-gasifier, fan-assisted cookstove in North India; (c) chimney stove and (d) traditional open fire in the western Guatemalan highlands. Source: Photos by Ajay Pillarisetti

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wood, dung, crop residues, coal, and charcoal—for basic household energy needs. India, China, and Sub-Saharan Africa account for approximately 70% of the population using solid fuels (23%, 17%, and 32%, respectively). Use of wood in high-income countries (HICs) persists in some areas, where it serves primarily as a heating fuel in the winter. Patterns of solid fuel use vary within and between countries and depend on seasonal needs, fuel availability, geography, and a variety of other factors. For example, in North India, households use a combination of wood and dung for specific tasks16–18 in distinct appliances. In Ghana,19 households rely on a combination of wood and charcoal. This type of mixed fuel and appliance use, also known as stacking,20–22 mirrors trends in highincome countries, where households may have a natural gas stove, oven, and charcoalfueled outdoor grill; electric appliances such as rice cookers and kettles; and biomassfueled fireplaces, all of which meet specific needs. Cultural allegiances toward biomass burning can impede transitions to cleaner fuels in both higher- and lower-income settings independent of rising income. The most commonly measured pollutants from biomass combustion are PM2.5 and CO, although studies have characterized other pollutants, including black carbon23 and polycyclic aromatic hydrocarbons.24 Three broad classes of measurements occur in studies of HAP: emission measurements from the stove’s plume, concentrations measured in rooms (e.g., kitchens and living areas), and exposures, measured by placing a sensor on a person that follows him or her through time and space. Between 1980 and 2016, more than 200 studies evaluated HAP concentrations and exposures.25,26 Available data show that levels of PM2.5 are highest during cooking in homes that burn dung (mean 7.8 ± 11.2 milligrams per cubic meter), followed by charcoal (3.9 ± 8.4 milligrams per cubic meter) and wood (2.1 ± 2.9 milligrams per cubic meter). Despite high spatiotemporal variability in emissions and exposures, households in LMICs are estimated to have annual average concentrations greater than both the World Health Organization Air Quality Guidelines27 and national air quality standards set by individual countries. Air pollution arising in the household escapes the indoor environment and can lead to substantial local and downstream exposure. For example, recent studies in India28–30 and China28,29,31 estimate that a large fraction of outdoor air pollution results from household combustion. In India, it is the largest single category contributing to outdoor pollution, and in China it is the second after industry. These studies suggest that cleaning up energy sources in rural homes benefits both the households themselves and their neighbors in urban areas, which is why cleaning up household energy sources is part of the Chinese national air pollution control strategy. Beyond air pollution, use of biomass fuel can lead to deforestation, and the burden of gathering fuel—a form of unpaid work—often falls on women and children. An estimated 30% of collected biomass is harvested nonrenewably, with large geographic variation,32

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potentially putting pressure on forests and other biomass resources. Daily fuel collection times range between 1 and 5 hours.33–35 In some contexts, these fuel collection practices also make people more susceptible to natural hazards and gender-based violence.33,36

Reducing Household Air Pollution The majority of household energy interventions to date have focused on burning biomass more cleanly and efficiently in cooking stoves. Although this has been shown to be possible in the laboratory using fairly sophisticated, highly engineered stoves with specific fuels, real-world performance has been suboptimal.37,38 This paradigm—making available biomass fuels “clean”—dominated traditional stove programs run by both nongovernment and government organizations. The largest of these programs occurred in India and China in the early 1980s, although only the program in the latter was considered successful at saving fuel. Figure 12.4 shows the relationship between HAP (and other forms of air pollution) and health. The most striking feature of the risk–response relationships39 is that they are nonlinear. This has profound implications for air pollution control measures, especially in the context of HAP; if the curves are correct, they imply that HAP must be reduced to very clean levels to reduce the burden of disease associated with exposure. Cleaner biomass stoves may simply not be clean enough to make a significant difference even if used. Thus, focus has shifted to making clean technologies (fueled by electricity or natural gas, liquefied petroleum gas, ethanol, or biogas) more broadly available.40 This shift mirrors fuel use in HICs, where few people rely on solid fuel for cooking and heating and instead use gas and electricity. Although gas and electricity are clean at the household level, these clean fuels pose other challenges—including cost, reliability of supply, accessibility, and cultural acceptance—that slow their full adoption. The government of India is implementing policies to accelerate the transition to clean cooking (Box 12.1); other countries, including Ecuador and Indonesia, have implemented broad, innovative policies to scale large fuel transitions in the past with varying degrees of success.

Outdoor Air Pollution Just as the primary driver of household air pollution is biomass burning, a primary driver of outdoor air pollution is fossil fuel combustion, with additional contributions from burning household biomass fuels and agricultural waste. And just as household air pollution claims millions of lives each year, outdoor air pollution has become responsible for an even larger toll, claiming an estimated 4.2 million lives in 2015 with a projected rise to 6.6 million deaths annually by 2050 unless current trends can be altered.7,41 Fossil fuels are the dominant form of energy used today (Figure 12.2). They include coal, oil, and natural gas and account for approximately 67% of total global energy

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Figure 12.4 Integrated exposure–response (IER) curves. The IERs describe the relationship between annual exposure to PM2.5 and relative risk of lower respiratory infection (LRI) in children and adults and, in adults, chronic obstructive pulmonary disease (COPD), ischemic heart disease (IHD, shown for adults age 25 to 30), lung cancer (LC), type 2 diabetes mellitus (T2DM), and stroke (shown for adults age 25 to 30). Relative risk is the ratio of the probability of an outcome occurring in those exposed to a given concentration of PM2.5 to the probability of that outcome among those unexposed. Curves were based on exposure and risk estimates from ambient air pollution, secondhand tobacco smoke, household air pollution, and active tobacco smoking studies. The modeling exercise used to generate these curves makes a number of assumptions, among which is that PM2.5 from all sources is equitoxic. Source: Burnett RT, Pope CA, Ezzati M, et al. An integrated risk function for estimating the global burden of disease attributable to ambient fine particulate matter exposure. Environ Health Perspect. 2014;122:397-403

consumption and 65% of electricity generation globally.1 Across their life cycle—from mining and extraction, to processing and refining, to transport, combustion, and waste management—they have impacts on human health and the environment at vast temporal and spatial scales. When combusted, fossil fuels release primary particles and other health- and environment-damaging pollutants into the environment. The primary pollutants of concern for health are PM2.5 and the pollutants that convert to ozone (O3) or secondary aerosols (particulates) downwind from sources. Of all fossil fuels, coal is the dirtiest and makes the largest contribution to air pollution. Direct byproducts of coal combustion include CO2, carbon monoxide (CO), sulfur oxides (SOx), nitrogen oxides (NOx), organic compounds, particulate matter, and mercury.

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Box 12.1. Subsidy to Social Investment in India: A Health Intervention Kirk R. Smith and Ajay Pillarisetti Liquefied petroleum gas (LPG), a hydrocarbon fuel composed mainly of propane and butane, is a byproduct recovered during the extraction and processing of most natural gas resources or during refining of crude oil. Unlike natural gas, under modest pressure LPG changes to liquid and can be transported safely in cylinders at ambient temperature, increasing its utility as a cooking fuel in areas where electricity and natural gas are not available or feasible. Recent increases in unconventional extraction of oil and gas resources has resulted in increased availability and lower prices of LPG on global markets, seeming to enable its use as a clean transition fuela over the next decades in many places that currently rely on biomass for cooking. One location where such a transition is rapidly occurring is India. Through innovative policy changes implemented from the top to the bottom of its government and facilitated by creative use of information technology (IT), India was able to provide access to LPG to approximately 95% of its households by 2019. Basically, by focusing public expenditures on the poor, India transformed the common pejorative term of subsidies into more aspirational social investments. Both mechanisms deploy taxpayer funds, but the second has an entirely different and more positive connotation.b Fuel subsidies have been common worldwide in many countries. Economists dislike them, considering them expensive to the government, an incentive for wasteful use, and a support mainly for the better off rather than the poor. In recent years some reforms have been successfully implemented, driven partly by the concern that subsidies may lead to excess use of fossil fuels that increase climate change risk. Indeed, India has made progress in eliminating fuel subsidies in the transport sector. LPG subsidies have been morphing through new programs that help them focus better on achieving social goals. To a great extent, the impetus for these policies arose from the government’s decision to take account of growing scientific knowledge of the health impacts of biomass fuel, the major fuel used by the poor. The long-term goal is a transition to electric cooking, but as an intermediate solution, LPG is healthier than biomass for the world’s poor.c India’s transformative policies began with a scheme called PAHAL (the Hindi acronym for Pratyaksh Hanstantrit Labh, or direct benefit transfer), through which all LPG came to be sold at market prices. Subsidies were paid directly to individual electronic bank accounts instead of reducing the price at the point of sale. This immediately became

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the largest bank transfer in human history from a government. With the expansion of digital identification cards known as Aadhar cards, cross-checking of data bases became possible, helping prevent fraudulent or redundant payments. This allowed both a substantial reduction in “ghost” and otherwise illegal accounts and decreased leakage of household cylinders into the commercial sector. Thus, the advantage of subsidized LPG was restricted, mostly, to individual households that were the intended beneficiaries of the program. Second, in 2015 came the Give It Up (GIU) campaign, an innovative approach to solve the challenge of withdrawing subsidies once they are no longer needed. Although the current middle class might have relied on the LPG subsidy 20 years ago, the roughly US$35 per year of public money per LPG connection today is no longer needed to keep them using the fuel. However, withdrawing the subsidy has two drawbacks: It is challenging to determine who truly does not need it, and people tend to treat long-term subsidies as entitlements (something they deserve) and forget the original intention of the programs that provide them (to help move them to clean fuel from dirty fuel). Instead of taking away the LPG subsidy, the GIU campaign asked people to voluntarily give it up with the proviso that the subsidy would be transferred to a poor household. Millions did—nearly 11 million households by mid-2018. The use of IT allows a donor to look up on a government-run website the name of the poor person who received a new LPG connection. Other features of GIU included wide use of social and conventional media campaigns and a coordinated promotional effort from the prime minister’s office on down. Unusually, the prime minister pushed clean cooking in dozens of speeches every month. Although not easily calculated, a conservative estimate is that US$330 million was being transferred annually by 2018 by the middle class to increase LPG use among the poor.d In 2016, the Pradhan Mantri Ujjwala Yojana (PMUY) campaign was initiated to bring 50 million new connections to poor households by 2019. New connections were provided only to women—an effort both to improve the status of women and to target the subsidies toward only one household member. In addition, 10,000 new LPG distributors were hired to supplement the existing 18,000. Such a major increase was needed because many poor households were in remote areas beyond the reach of existing distributors. Being ahead of schedule, in 2018, the government announced that the target had been expanded to 80 million households before 2021, some 500 million people. This target was reached in early September 2019. Notably, the cost to the Indian taxpayer decreased as the program continued, with a net savings estimated at more than US$3 billion by better targeting to the poor.

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Provision of an LPG connection does not instantly make everyone a full user. The refill rate of PMUY households that have had their connection for at least a year seems to be about four cylinders, 60% of the expected full usage for a rural household. This is consistent with introduction of other new health-promoting technologies that require behavioral change, such as latrines, bednets, condoms, and institutional labor and delivery facilities. Provision of the better technology is just half the battle; the next portion is to encourage proper usage. From a health perspective, of course, the LPG stove must be used nearly all the time and the biomass stove not used in order for the air pollution benefits to accrue.e Thus, although more work is needed, a remarkable start has occurred. References a. Shen G et al. Evaluating the performance of household liquefied petroleum gas cookstoves. Environ Sci Technol. 2018;52(2): 904–915. b. Smith KR. Pradhan Mantri Ujjwala Yojana: transformation of subsidy to social investment in India. In: Debroy B, Gangul A, Desai K, eds. Making of New India: Transformation under Modi Government. New Delhi, India: Dr. Syama Prasad Mookerjee Research Foundation and Wisdom Tree; 2018:401–410. c. Goldemberg J, Martinez-Gomez J, Sagar A, Smith KR. Household air pollution, health, and climate change: clearing the air [Editorial]. Environ Res Lett. 2018;13:030201. d. Mittal N, Mukherjee A, Gelb A. Fuel subsidy reform in developing countries: direct benefit transfer of LPG cooking gas subsidy in India. CGD Policy Paper 114. Washington, DC: Center for Global Development; 2019. e. Harish S, Smith KR, eds. Ujjwala 2.0: from access to sustained usage. Policy Brief CCAPC/2019/03. New Delhi, India: Collaborative Clean Air Policy Centre; 2019.

Coal combustion also contributes to the formation of secondary organic aerosols and ozone, which affect areas downwind of where primary pollutants are released. The health impacts of coal combustion are substantial and vary widely between countries. In China, coal combustion was estimated to be the most important source of ambient PM2.5 concentrations, contributing approximately 40% of population-weighted exposure and resulting in an estimated 366,000 deaths in 2013.31 In India, coal combustion contributed approximately 16% of the total population-weighted PM2.5 exposure and was responsible for approximately 169,000 deaths in 2015.30 Petroleum combustion yields a variety of byproducts similar to those of coal combustion, including CO2, CO, NOx, SOx, and particulate matter. One of the largest uses of petroleum is as a fuel for personal transportation, the direct and indirect health impacts of which have been well described.42–44 Other uses of petroleum—for heating45,46 and for

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sea-based transport47—have been implicated in recent years in both emissions of hazardous pollutants and health effects. All in all, household air pollution from biomass burning and outdoor air pollution associated with fossil fuel combustion for electricity generation, heating, and transportation are responsible for enormous global burdens of disease, primarily from heart disease, stroke, lung disease, and cancer. The specific health effects are more fully explored in Chapter 7. Transitioning away from these fuel sources toward clean and renewable sources would save millions of lives each year.

Climate Change In addition to its large contribution to illness and death from air pollution, the combustion of fossil fuels is also the primary driver of global climate change (see Chapter 4 for an introduction to the science of climate change). Burning fossil fuels releases climate-altering pollutants, including CO2, methane, and black carbon (the main component of soot, produced by the incomplete combustion of fossil fuels). Different fossil fuels have varying impacts on global climate because the amount of these pollutants released per unit of energy produced varies from fuel to fuel (sometimes called their “carbon intensity”). This has important implications for how best to address climate change. The numerous health impacts of climate change are reviewed in Chapter 10.

Climate Implications of Different Energy Sources Fossil Fuels Coal Coal supplied 27% of global primary energy and was used as fuel for 38% of global electricity generation in 2017.1 In the same year, China, India, and the United States were the world’s largest producers of coal, producing about 45%, 10%, and 9% of the world’s total, respectively. Globally, coal combustion was responsible for approximately 44% of anthropogenic CO2 release.1,48 Coal is thus a significant contributor to global climate change, with the highest overall life cycle emissions in grams of CO2-equivalent per kilowatt hour among major alternatives (Figure 12.5).

Petroleum Petroleum is a liquid mixture of aliphatic and aromatic hydrocarbons that, when refined, yields a variety of products, from lubricants to asphalt, but most becomes fuel.3 Globally, petroleum accounts for 41% of primary energy consumption,1 approximately 94% of transportation fuel use,49 and 4% of electricity generation;1 it results in approximately 35% of global CO2 emissions.50 It has a slightly lower carbon intensity than coal, which

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Figure 12.5 An overview of life cycle emissions of CO2 by currently available electricity generation technologies. The colors represent the source of the emissions. Source: Adapted from data available in Appendix Table A.III.2 of Bruckner T, Bashmakov IA, Mulugetta Y, et al. Chapter 7: Energy Systems. In: Edenhofer O, Richs-Madruga R, Sokona Y, et al, eds. Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK: Cambridge University Press; 2014.

despite a similar share of total energy contributes a larger proportion of total CO2 emissions. When refined, a 42-gallon barrel of crude oil yields approximately 20 gallons of gasoline, 9 gallons of diesel fuel and heating oil, 3 gallons of jet fuel, and smaller amounts of other products such as liquefied petroleum gas and propane, some of which goes to heating and power generation.4 The decrease in easily accessible traditional crude oil has shifted focus to extraction of oil from tar sands, a mixture of sand, water, and the hydrocarbon bitumen, which can be processed into oil. Between 2010 and 2014, global investment in oil sands and other nontraditional extraction methods increased from 20% to 30% of total investment; production from these methods increased to approximately 12.2 million barrels per day, or 16% of total global crude oil production.51 Between 2015 and 2040, it is estimated that overall oil production will continue to increase, with more than half coming from nontraditional sources (unless there is rapid electrification of the world’s vehicle fleet). The climate impacts of such extraction are profound; the energy intensity needed for

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extraction, separation, and enhancement of oil sands compared with traditional crude extraction methods contributes perhaps three to four times more emissions of climatealtering pollutants.52,53 Beyond climate impacts, tar sands production is one of the largest contributors to secondary organic aerosol formation in North America54 and can lead to dramatic local environmental and ecosystem degradation.53,55 For example, by 2013 it was estimated that the Athabascan tar sands operation had cleared or disturbed approximately 813 square kilometers of forested land in the Canadian province of Alberta (see section 4.3 of McIntosh and Pontius56 for details on the scale of the impacts). The total energy industry footprint in Alberta is significantly larger, at approximately 12,000 square kilometers.57 As with byproducts of coal mining, much of the waste from tar sands processing, known as tailings, is stored in ponds that can leach chemicals into the local watershed.58

Natural Gas Natural gas is a colorless and odorless hydrocarbon mixture (primarily methane) formed under the earth’s surface from one of three processes: thermogenic (the slow decomposition of organic material), biogenic (through processes of methanogenic bacteria), and abiogenic (from the reduction of carbon dioxide during the cooling of magma).59 Natural gas production and recovery have been increasing steadily over the past decade; it now accounts for 23% of electricity generation and 22% of total primary energy supply globally.1 It has been considered a promising transitional energy source to a sustainable world energy system because its carbon intensity is lower than that of traditional fossil fuels such as coal (Figure 12.5), although leaks of methane into the environment and the energy intensity of unconventional gas recovery diminish the magnitude of that advantage.60–62 Natural gas demand has increased rapidly in recent years, with the United States and China leading growth.63 Increases in production have been led by the United States, which accounts for 30% to 40% of global production.63 American production, in turn, has been driven by increases in horizontal drilling and hydraulic fracturing in shale and sandstone, which accounted for approximately 50% of all dry natural gas production in 2015 and is estimated to account for about 70% of all production by 2040.64 It remains an area of active debate whether promoting electricity generation through natural gas combustion is an important step in our transition away from more carbon-intensive fossil fuels or whether the construction of infrastructure such as pipelines and gas-fired power plants threatens to increase long-term reliance on fossil fuels while providing only modest climate benefits.

Additional Occupational and Environmental Health Impacts of Fossil Fuels In addition to the negative impacts on air quality and the global climate, the production of fossil fuels is also associated with occupational hazards and local environmental impacts. In 2012, approximately 7 million people globally—about 0.2% of the global

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workforce—were employed by the coal industry,65 and the International Labor Organization estimates that 8% of workplace fatalities occur among these workers (Figure 12.6).66–68 Occupational exposures during coal mining activities can result in respiratory illness, including silicosis and coal mine dust lung disease.69,70 Mining additionally disrupts ecosystems, alters environmental flows, and can contaminate local water supplies and soil. To prepare mined coal for combustion or industrial processes, it is washed in a mixture of chemicals to reduce impurities that include clay, rocks and minerals, and heavy metals. The chemicals used in processing coal include carcinogens and substances linked with heart and lung damage.71 Exploration, drilling, and extraction of oil also pose numerous occupational hazards and risks to local environments. Workplace harms include ergonomic hazards, noise,

Figure 12.6 Deaths per million tons coal produced in China, India, and the United States. Although the numbers in India and China are decreasing, they are much higher than in the United States, which has seen an uptick in recent years. Sources: Jennings N. Mining: an overview. In: Stellman J, ed. Encyclopedia of Occupational Health & Safety. Geneva, Switzerland: International Labor Organization; 2011. Chu C et al. Statistical analysis of coal mining safety in China with reference to the impact of technology. J South Afr Inst Min Metall. 2016;116:73–78. Wang L, Cheng YP, and Liu HY. An analysis of fatal gas accidents in Chinese coal mines. Saf Sci. 2014;62:107–113.

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vibration, chemical exposure, and physical strain from long working hours.72,73 Largescale leaks and spills both of petroleum and of waste materials are fairly common; since the beginning of 2017, spills have been reported near Chennai, India; in the Alaskan Arctic; near Greece; in the Gulf of Mexico; in the East China Sea; and in Indonesia. Large spills, such as the 2010 Deepwater Horizon incident,74 cause considerable ecological damage and affect human health both directly and indirectly (for a summary of marine oil blowouts, tanker oil spills, and other oil-related environmental contamination incidents, see Jernelöv 201075). Exposures to spilled oil, its byproducts, and various chemicals used for cleanup have been shown to result in high concentrations of various aromatic compounds in blood months after exposure,76 altered profiles of hematological, hepatic,77 and respiratory function,78–80 and other adverse outcomes.81 As with coal, a number of potential exposures may occur throughout the petroleum processing life cycle. Cohort studies82 have shown increases in cancer among petroleum workers,83 including exposuredependent associations with multiple types of cancer.83,84 Occupational risks associated with gas exploration and recovery are similar to those experienced by oil workers. Chemicals used throughout the conventional and unconventional gas recovery process pose risks to workers and potentially to nearby communities.85,86 Broader health implications of unconventional gas development are described in Box 12.2.

Nuclear Energy In 2016, approximately 450 nuclear reactors were active globally, with a total generation capacity of approximately 390 GW, accounting for approximately 10% of global energy supply and 11% of electricity generation.1 Only France (approximately 73%) and Ukraine (approximately 50%) sourced 50% or more of their total domestic energy generation from nuclear. In the United Kingdom, the United States, and Russia, nuclear provided approximately 20% of total domestic generation. Major benefits of nuclear power are that it produces energy without generating either the air pollution or greenhouse gases associated with fossil fuels. Despite this, growth rates of nuclear power have fallen short of projections and expectations, in large part because of fuel security issues related to terrorism, uncertainties about disposal of nuclear waste, and safety concerns following the Fukushima accident, and the extra costs and financial risks borne by utilities as a result. The complexities of the nuclear fuel cycle are beyond the scope of this chapter, but each step in the process of producing nuclear energy—from mining ore to radioactive waste disposal—can lead to exposure to radioactivity and chemical and radioactive waste. Health risks related to nuclear power fall into four broad categories. First, there are occupational risks for workers in nuclear facilities and as part of mining operations. The primary concern for those working in the nuclear industry is elevated cancer risk87–90 arising from chronic, low-level exposure to radiation.91 Relatedly, there are risks to communities surrounding nuclear power plants. Uranium mining generates large amounts of

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Box 12.2. The Environmental Health Dimensions of Oil and Gas Development Lee Ann L. Hill and Seth B. C. Shonkoff Oil and gas development poses known hazards to human health through the release of contaminants to air, water, and soil. Innovations in hydraulic fracturing and directional drilling technologies, accompanied by political demands for decreased reliance on internationally sourced fossil energy, have led to a significant increase in oil and gas production in the United States over the past decade. Much of the increase in production is called “unconventional,” referring both to the sources (e.g., shale and other low-permeability geological formations) and the techniques used to extract the oil and gas (e.g., hydraulic fracturing, or “fracking”). This rise in production has catalyzed a rapid expansion of scientific study of the human health impacts of oil and gas development. Air Pathways, Proximity, and Density Human exposure to oil- and gas-attributable air pollutants can occur via unintentional releases (e.g., leaks and blowouts) and intentional emissions during operations and maintenance (e.g., venting and blowdowns to relieve pressure, and oil–water separation and processing). Many of these emissions contain carcinogens and hazardous air pollutants that may pose health risks to nearby communities.a Both epidemiological studies and risk assessments find adverse health impacts associated with unconventional oil and gas development. High well density and residential proximity to unconventional gas development are associated with high-risk pregnancies and various poor birth outcomes, including congenital heart defects, preterm birth, and intrauterine growth restriction.b–g Proximity to oil and gas development has also been associated with increased cancer incidence and prevalence,h hospital visits for cardiovascular and neurologic outcomes,i and asthma exacerbation.j Finally, risk assessments have shown increases in both noncancer and cancer risks with increasing proximity to unconventional oil and gas development. In some cases, these risks exceed the U.S. Environmental Protection Agency acceptable levels of risk of 1 case per 10,000 individuals by approximately eightfold.k,l Noise Proximity to unconventional oil and gas development is also associated with elevated noise exposure. During well construction and drilling, noise in nearby residential areas has reached levels associated with nausea, headaches, sleep disturbance, and cardiovascular disease.m,n Compressor stations used in oil and gas development and transport can produce noise at levels associated with sleep disturbance.o

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Chemical Use and Water Pathways Oil and gas activities have the potential to contaminate both surface water and groundwater through various mechanisms. Water contamination attributed to oil and gas development is primarily from subsurface migration of fluids and lack of isolation of wellbores from groundwater, the use of chemical additives and stimulation fluids, and the handling, discharge, and reuse of wastewater (produced water and flowback). Spills, leaks, and intentional discharge of wastewater at the surface can contaminate soil, surface water, and groundwater. In key oil- and gas-producing states, half of reported spills related to unconventional development are associated with the storage and transport of fluids via flowlines; however, reporting requirements vary by state, suggesting that spill frequency and spill volumes are probably underreported.p Chemicals used in stimulation fluids and for well drilling, routine maintenance, and wellbore cleanouts and their derivative products partially drive the composition of produced water. A number of these compounds are associated with a variety of cancersq and noncancer health effects.r–v Assessing the health impacts of and potential exposures to these chemicals is complicated given that the chemical composition of stimulation and other injectate fluids and produced water varies across geography, geology, and time. Many emerging chemicals lack basic toxicological information, and constituents and toxicological profiles of proprietary compounds are often not publicly disclosed. Groundwater can also become contaminated when wastewater is disposed of and injected into aquifers that are or could be sources for municipal or domestic consumption.w Additionally, disposal of produced water into unlined pits and impoundments has been documented to affect underlying and nearby groundwater resources and domestic water wells.x This disposal practice is occurring on a large scale in California’s San Joaquin Valley.y Emerging Issues One key emerging issue surrounding human health and oil and gas development is the management of waste in general and the reuse of liquid waste in particular. Produced water from oilfields is increasingly used to irrigate food crops for human and livestock consumption,z for the watering of livestock, and for de-icing and dust suppression on roads. The potential human health implications of these practices are still largely unknown and are under investigation.aa,bb Produced water is generally highly saline and includes mixtures of naturally occurring chemicals, chemical additives, and their daughter products and synergistic byproducts. Depending on the petroleum geological formation, produced waters may also contain naturally occurring radioactive materials (including radium-226, radium-228,

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and uranium). In Pennsylvania, the practice of spreading produced water salts for deicing releases a greater quantity of radium to the environment than all treatment facilities and wastewater spill events statewide combined, raising questions about environmental fate and transport and potential human exposures.cc Conclusions Although health hazards, risks, and impacts associated with oil and gas development continue to be studied, approximately 17.6 million Americans currently live within 1 mile of an active oil or gas well.dd Key consideration should be given to protecting groundwater resources designated for federal protection near oil and gas development, especially those that are currently or may be used for future domestic, municipal, and agricultural consumption.ee Approaches that safeguard ground and surface water quality, reduce emissions of health-damaging air pollutants, and require minimum setbacks separating oil and gas operations from where people live, work, and play are key strategies to reduce environmental degradation and human exposures to health-damaging pollutants from the development of oil and gas. References a. Garcia-Gonzales DA, Shonkoff SBC, Hays J, Jerrett M. Hazardous air pollutants associated with upstream oil and natural gas development: a critical synthesis of current peer-reviewed literature. Ann Rev Public Health. 2019;40(1):283–304. b. Casey JA, Savitz DA, Rasmussen SG, et al. Unconventional natural gas development and birth outcomes in Pennsylvania, USA. Epidemiology. 2016; 27(2):163–172. c. McKenzie LM, Guo R, Witter RZ, Savitz DA, Newman LS, Adgate JL. Birth outcomes and maternal residential proximity to natural gas development in rural Colorado. Environ Health Perspect. 2014;122(4):412–417. d. Whitworth KW, Marshall AK, Symanski E. Maternal residential proximity to unconventional gas development and perinatal outcomes among a diverse urban population in Texas. PLoS One. 2017;12(7):e0180966. e. Stacy SL, Brink LL, Larkin JC, et al. Perinatal outcomes and unconventional natural gas operations in southwest Pennsylvania. PLoS One. 2015;10(6):e0126425. f. Currie J, Greenstone M, Meckel K. Hydraulic fracturing and infant health: new evidence from Pennsylvania. Sci Adv. 2017;3(12):e1603021. g. Whitworth KW, Marshall AK, Symanski E. Drilling and production activity related to unconventional gas development and severity of preterm birth. Environ Health Perspect. 2018;126(3):037006. h. McKenzie LM, Allshouse WB, Byers TE, Bedrick EJ, Serdar B, Adgate JL. Childhood hematologic cancer and residential proximity to oil and gas development. PLoS One. 2017;12(2):e0170423. i.

Jemielita T, Gerton GL, Neidell M, et al. Unconventional gas and oil drilling is associated with increased hospital utilization rates. PLoS One. 2015;10(7):e0131093.

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j. Rasmussen SG, Ogburn EL, McCormack M, et al. Association between unconventional natural gas development in the Marcellus Shale and asthma exacerbations. JAMA Intern Med. 2016;176(9):1334–1343. k. McKenzie LM, Witter RZ, Newman LS, Adgate JL. Human health risk assessment of air emissions from development of unconventional natural gas resources. Sci Total Environ. 2012;424:79–87. l. McKenzie LM, Blair BD, Hughes J, et al. Ambient non-methane hydrocarbon levels along Colorado’s Northern Front Range: acute and chronic health risks. Environ Sci Technol. 2018;52(8):4514–4525. m. Hays J, McCawley M, Shonkoff SBC. Public health implications of environmental noise associated with unconventional oil and gas development. Sci Total Environ. 2017;580:448–456. n. Blair BD, Brindley S, Dinkeloo E, McKenzie LM, Adgate JL. Residential noise from nearby oil and gas well construction and drilling. J Expo Sci Environ Epidemiol. 2018;28:538–547. o. Boyle MD, Soneja S, Quirós-Alcalá L, et al. A pilot study to assess residential noise exposure near natural gas compressor stations. PLoS One. 2017;12(4):e0174310. p. Patterson LA, Konschnik KE, Wiseman H, et al. Unconventional oil and gas spills: risks, mitigation priorities, and state reporting requirements. Environ Sci Technol. 2017;51(5):2563–2573. q. Elliott EG, Trinh P, Ma X, Leaderer BP, Ward MH, Deziel NC. Unconventional oil and gas development and risk of childhood leukemia: assessing the evidence. Sci Total Environ. 2017;576:138–147. r.

Webb E, Bushkin-Bedient S, Cheng A, Kassotis CD, Balise V, Nagel SC. Developmental and reproductive effects of chemicals associated with unconventional oil and natural gas operations. Rev Environ Health. 2014;29(4):307–318.

s. Kassotis CD, Bromfield JJ, Klemp KC, et al. Adverse reproductive and developmental health outcomes following prenatal exposure to a hydraulic fracturing chemical mixture in female C57BI/6 mice. Endocrinology. 2016;157(9):3469–3481. t. Webb E, Moon J, Dyrszka L, et al. Neurodevelopmental and neurological effects of chemicals associated with unconventional oil and natural gas operations and their potential effects on infants and children. Rev Environ Health. 2018;33(1):3–29. u. Webb E, Hays J, Dyrszka L, et al. Potential hazards of air pollutant emissions from unconventional oil and natural gas operations on the respiratory health of children and infants. Rev Environ Health. 2016;31(2):225–243. v. Kassotis CD, Klemp KC, Vu DC, et al. Endocrine-disrupting activity of hydraulic fracturing chemicals and adverse health outcomes after prenatal exposure in male mice. Endocrinology. 2015;156(12):4458–4473. w. California Council on Science and Technology. Impacts of well stimulation on water resources. In: An Independent Scientific Assessment of Well Stimulation in California. 2015. https://ccst.us/wp-content/uploads/160708-sb4-vol-II-2.pdf x. DiGiulio DC, Jackson RB. Impact to underground sources of drinking water and domestic wells from production well stimulation and completion practices in the Pavillion, Wyoming, field. Environ Sci Technol. 216;50(8):4524–4536.

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y. DiGiulio DC, Shonkoff SBC. Potential impact to groundwater resources from disposal of produced water into unlined produced water ponds in the San Joaquin Valley. An assessment of oil and gas water cycle reporting in California. Preliminary evaluation of data collected pursuant to California Senate Bill 1281, Phase II. In press. z. California State Water Resources Control Board. Food Safety Expert Panel recycled oilfield water for crop irrigation: fact sheet. 2019. https://www.waterboards .ca.gov/centralvalley/water_issues/oil_fields/food_safety/data/fact_sheet/of_food safety_fact_sheet.pdf aa. DiGiulio D, Shonkoff SBC. Is reuse of produced water safe? First, let’s find out what’s in it. EM Magazine. August 1, 2017. bb. Shonkoff SBC, Domen JK, Stringfellow WT. 2016. Hazard assessment of chemical additives used in oil fields that reuse produced water for agricultural irrigation, livestock watering, and groundwater recharge in the San Joaquin Valley of California: preliminary results. PSE Healthy Energy. September 2016. https://www .psehealthyenergy.org/our-work/publications/archive/hazard-assessment-of -chemical-additives-used-in-oil-fields-that-reuse-produced-water-for-agricultural -irrigation-2/ cc. Tasker TL, Burgos WD, Piotrowski P, et al. Environmental and human health impacts of spreading oil and gas wastewater on roads. Environ Sci Technol. 2018;52(12):7081– 7091. dd. Czolowski ED, Santoro RL, Srebotnjak T, Shonkoff SBC. Toward consistent methodology to quantify populations in proximity to oil and gas development: a national spatial analysis and review. Environ Health Perspect. 2017;125(8):086004. ee. DiGiulio DC, Shonkoff SBC, Jackson RB. The need to protect fresh and brackish groundwater resources during unconventional oil and gas development. Curr Opin Environ Sci Health. 2018;3:1–7.

waste material, which may contain low-level radioactivity, metals, and acids. Its release into the environment can harm ecosystems and lead to exposures from consumption of contaminated drinking water and food.3 Additionally, during routine operation, nuclear reactors release radioactive gas into the atmosphere and liquids into nearby bodies of water. However, the resulting doses are small compared with exposures from natural or medical sources.3 The relationship between nuclear power and cancer in communities downwind of plants is controversial. A 2014 meta-analysis of fourteen studies found no association between childhood leukemia and living within 25 kilometers of a nuclear power plant; however, a secondary analysis indicated a weak but statistically significant excess of leukemia in children under 5 living within 5 kilometers of nuclear power plants, consistent with the findings of other studies.92 If countries continue to move away from nuclear power, as is the projected trend, this concern may be minimized over time; furthermore, governments will need to weigh the uncertainty of the described evidence with issues of public perception and clean energy needs.

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Second, there are risks associated with nuclear accidents, the most publicly visible risks of nuclear power, despite their relative infrequency and low mortality overall. Major incidents to date include accidents at Three Mile Island (United States, 1979), in Chernobyl (Ukraine, 1986), and at Fukushima (Japan, 2011). Only the second of these caused significant human health impact, however. For a review of past disasters, see Hasegawa et al.93 Third, there is the challenge of nuclear waste storage and disposal. An estimated 12,000 tons of high-level waste that consists primarily of uranium is generated yearly, in addition to an estimated 250,000 tons of existing material.94 Current storage plans include seclusion of highly radioactive material deep underground, in artificial storage vessels surrounded by natural features that prevent leakage into the environment.95 There are few such facilities, and siting them can be contentious because of local opposition. Lastly, nuclear materials capable of being used as radioactive weapons or developed into nuclear weapons can be diverted from the nuclear power fuel cycle to subnational (terrorist) groups. To date, this has apparently not happened because of international agreements and stringent controls applied throughout the world,96 but if the nuclear power enterprise becomes large enough to significantly offset climate impacts, the amount of dangerous materials in circulation would be more difficult to keep under strict control. The risks in these cases are hard to quantify, and success to date, though encouraging, does not guarantee future success.

Renewable Energy Renewable sources present numerous advantages over fossil fuels and, to some extent, nuclear energy. They do not deplete finite resources, produce little air pollution, and have negligible climate impacts compared with fossil fuels. They enable nations and communities to envision an aspirational future in which electricity from clean sources powers most, if not all, energy needs of households, villages, cities, and civilizations—from lighting, cooking, and heating to local and long-distance travel. Before that vision becomes a reality, however, renewables mixed with cleaner fossil fuels, such as natural gas and liquified petroleum gas (LPG), may provide a path forward. Renewables are not a panacea; they present issues of land use and ownership and material and energy inputs, and they often necessitate energy storage, which can have broad economic and environmental health impacts.

Solar Photovoltaic (PV) cells are the dominant method by which electricity is generated from solar radiation. Between 2005 and 2016, solar PV electricity production increased globally from approximately 4 terawatt hours (TWh) to 330 TWh (approximately 1% of total energy production), led by China (75 TWh, 1.2% of national energy production), Japan (51 TWh, 5%), the United States (47 TWh, 1.1%), and Germany (38 TWh, 6%).1 Other forms of solar power generation exist but are much less widely deployed. Solar thermal power systems

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heat a transfer fluid, which is used to produce steam and then converted into mechanical energy in a turbine, in turn powering a generator and producing electricity. Solar towers use an array of mirrors to focus sunlight on a central location and store heat energy in molten salts, which are used to boil water, produce steam, and turn turbines.97 The health and environmental concerns from solar power relate largely to the life cycles and recyclability of PV cells and battery storage technologies. PV panel waste is expected to reach approximately 10 million tons in 2050.98 A review of end-of-life options for PV cells found that no specific solar panel recycling plants exist yet.99 The extraction and mining of compounds used in PV panels and their fabrication pose occupational risks to workers. Solar thermal and solar tower power plants require sophisticated components but are estimated to have much lower lifetime environmental impacts than fossil fuel power sources.100,101 Solar power has additional consequences for the environment, including alterations to landscapes and land usage and, in the case of solar thermal plants, water usage.97 Overall, however, the environmental and health impacts of PV are low, probably far less than those from any fossil fuel.

Wind Worldwide, wind electricity production reached approximately 960 TWh in 2016 (3.8% of total global production), up from 104 TWh in 2005.1 Global wind potential is high, with limited impacts on human health and numerous benefits, including the absence of direct production of climate-altering pollutants and no regular waste stream.102 As with other renewable sources of energy, climate-altering pollutants are emitted during equipment production, but given the long lifetime of wind turbines, these emissions are minimal per unit of electricity produced. Health and environment concerns associated with wind fall into a few broad categories. First, wind, like solar, operates at low energy density and so requires expanses of land or sea where turbines can be placed. Unlike solar, however, the area surrounding wind turbines may be usable for other purposes. Offshore wind turbines may have impacts on marine ecosystems from noise, vibration, and electromagnetic currents. Studies of people living near wind turbines have found associations between the turbines and annoyance, changes in psychological state, sleep perturbation, and decreased quality of life.103–105 Overall, wind power poses limited climate- and health-related threats to the population when compared with conventional fossil fuel alternatives.

Hydroelectric Hydropower is generated when falling or flowing water strikes the blades of a turbine, which in turn generates electricity.3 In 2016, approximately 4,200 TWh of electricity was generated from hydropower, approximately 17% of the world’s electricity supply.106 The

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size of hydropower installations ranges widely, from small-scale, community hydroelectric installations to enormous installations, such as China’s Three Gorges Dam. Larger hydroelectric plants feature dams that create large reservoirs for electric power generation, flood control, water storage for households and communities, recreation opportunities, as well as other industrial and agricultural uses. Hydropower is growing rapidly worldwide, with thousands of new installations expected to be built and come online in the next few decades.107 Recent reviews estimate that more than 200 large dams (60 meters or higher) are planned in forty-nine countries explicitly for hydropower,108 and more than 80,000 small hydropower plants are operating or under construction in 150 countries.109 This growth reflects widespread acceptance of hydropower as a clean source of energy but may neglect environmental impacts on river ecosystems, including altered water flow, temperature, and quality (including chemical contamination and alterations in turbidity), and disruption of fish migratory patterns and potential for extinction of some species.110–112 Furthermore, recent estimates of the climate impact of hydropower indicate that although over the lifetime of an installation emissions are lower than for traditional fossil fuels, dam-created reservoirs can be a significant emitter of greenhouse gases (Figure 12.5).107 Health impacts of hydropower fall into three broad categories: population displacement, infectious disease risk, and disasters related to dam failure.3 An estimated 40 to 80 million people have been involuntarily displaced by dam construction,113 and approximately 470 million people live in regions affected by dam development.114 Often, these populations are poor, depend on rivers for livelihoods, and confront numerous other social and health challenges.115–118 Relocation of such populations can result in wide-ranging social and health impacts, including impoverishment, homelessness, stress, worse self-rated health, and depression.119–121 By altering hydrology, water flow, and habitats for disease vectors, hydroelectric dams can have an impact on infectious disease by altering patterns of contact between vectors and hosts.122–125 For example, dams in West Africa have been responsible for large increases in prevalence of schistosomiasis (the vector is a freshwater snail). Epidemics of malaria and other vector-borne diseases have followed dam construction in other parts of the world.126,127 This topic is covered in more depth in Chapter 6. Dam failures can occur as a result of engineering flaws, collection of sediment in reservoirs, or aging materials used in their construction.128 Failures can be catastrophic. In 2018, heavy rain and flooding caused the collapse of an auxiliary dam at the Xe-Pian XeNamnoy hydroelectric project in Laos, releasing 170 billion cubic feet of water.129 Severe rainfall events, which are becoming more frequent in some places because of climate change, may contribute to dam failures.

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Biofuels Biofuels are derived from recently formed biomass and have been categorized as falling into four basic generations.130 First-generation biofuels convert the sugar and starch portions of feedstocks such as sugarcane, corn, and cassava into ethanol. Second-generation biofuels convert agricultural and forest residues and feedstock such as trees, straw, and bagasse into ethanol and methanol; these fuels use the entire plant. Third-generation biofuels use advanced biotechnology to manipulate algae to act as a high-energy and renewable feedstock that can be produced at low cost. Fourth-generation biofuels are under development and rely on advanced synthetic biology.130 Currently, first- and second-generation biofuels are available and used primarily as liquid transportation fuels, usually as gasoline additives. The development of second-, third-, and fourth-generation biofuels focuses on reducing use of food crops for fuel production in order to prevent distortion in global food prices, maintain land for food production, and reduce water and fossil fuel use. Global biofuel production has increased substantially since 2000, when approximately 4.5 billion gallons of bioethanol was produced. In 2013, approximately 23.4 billion gallons was produced, with the majority of production being in the United States, Brazil, and Europe.131 For comparison, total production of liquid fuel is about 4.2 billion gallons per day.132 Growth in biofuels is spurred in part by two health benefits: reduction of greenhouse gas emissions and reduction of air pollution.133 Both of these benefits have come under scrutiny in recent years. Life cycle analyses of first- and second-generation biofuels show that their climate advantage may be minimal or net negative,130,134-136 largely because of carbon released during the conversion of land to facilitate crop growth and the application of nitrogen-based fertilizers.137 The magnitude of the impacts is highly dependent on the assumptions about feedstocks, planting, harvesting, and processing methods.130,138 Similarly, both measured and estimated emission reductions from the use of blended fuels (ethanol and gasoline) are inconsistent, varying with pollutant, operating conditions, vehicle age and type, and possibly the fuel’s feedstock.139 In general, however, life cycle ambient air quality estimates made for increased use of ethanol in the United States as a transportation fuel indicate that emissions of PM and CO are higher for ethanol than for gasoline.130,133,138 Tailpipe emissions of blended fuels have lower CO and PM emissions but higher emissions of other combustion byproducts, including volatile organic compounds, which may contribute to ozone-forming potential.130,139 A related use of biomass and biofuels is the production of feedstocks that absorb CO2 during their growth and are subsequently combusted in facilities that capture and sequester carbon (carbon capture and sequestration). This technology is attractive because of its theoretical potential to be carbon negative; by absorbing CO2 during plant growth and then capturing it during combustion, the process has the potential to remove more CO2

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from the atmosphere than it produces. Existing infrastructure for such projects is limited and considered technologically immature.140 However, potential for CCS at existing biofuel plants is high and may pave the way for larger-scale biofuel-based carbon capture and sequestration.140 A number of other potential issues arise with biofuels throughout their life cycle. From an occupational standpoint, agricultural work (including manual sugarcane harvesting, as is still practiced in some parts of Brazil) and exposure to biological and chemical agents are of concern. Little exact quantification of these risks has been undertaken, but common components of ethanol manufacturing include sodium hydroxide, ammonia, sulfuric acids, antibiotics, and yeasts.139,141 Additionally, in Brazil, for example, burning of sugarcane fields is common practice and has affected local and regional air quality and health. Land transitioned to production of feedstock crops may suffer nutrient and water depletion or water pollution. Finally, use of crops typically reserved for food may disrupt global food markets and poses a “food versus fuel” dilemma—an excellent example of the complex issues that emerge in the field of planetary health. A rich literature debates the extent to which biofuels affect food prices and supplies.142-145 In the United States, for example, biofuels are thought to have decreased fuel prices and led to slight increases in food prices that disproportionately affect the poor.142 Volatile food prices are thought to affect net importers of food, often in low-income countries, most adversely.143,146 Establishing the proper role for biofuels in current and future global energy mixes will require more in-depth evaluation of their total life cycle impacts on climate and health. Further development of second-, third-, and fourth-generation biofuels may allay many of these concerns and allow productive use of land for both food and fuel needs. Policies focused on biofuel development will need to continue to balance competing concerns about climate, health, and food system sustainability.

Emerging Issues Wind and PV power provide intermittent energy (only when the wind blows or the sun shines), sometimes limiting the reliability of power systems. For example, in February 2008, meteorological changes in west Texas resulted in decreased output from wind farms, resulting in brownouts in thousands of homes.147 A number of technologies that store energy exist. Pumped storage hydropower, where water is pumped uphill to a reservoir with excess electricity and released downhill when needed, is the oldest and most common form of storage. Compressed-air energy storage relies on pumping air during low demand periods into large underground caverns and releasing it through turbines as needed. Although fairly efficient, it has not been widely used. Flywheels store electrical energy as kinetic energy by accelerating a flywheel at very high speeds; as the flywheel slows down, electricity can be produced in a generator.

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Perhaps the most promising form of storage is batteries, as battery technology has advanced greatly in recent years because of the mobile phone and portable electronics industries and the growing development of electric vehicles.148,149 Advanced batteries offer reasonable lifetimes and storage densities but remain expensive to deploy at scale. From a health perspective, many of these batteries pose a future challenge; small batteries in electronics have an average lifespan of 2–4 years and rapidly growing global use.148 Therefore, they will contribute substantially to global electronic waste streams. Lithium-ion batteries, in particular, are promising energy storage solutions for electric vehicles and renewable energy systems. By 2040, annual waste flows of these batteries may reach as much as 340,000 metric tons,149 indicating a need to evolve significant global facilities to recycle components and retrieve and repurpose elements and compounds used in their manufacture and assembly. Mining for heavy metals needed in batteries is also a major local polluter, and calls are being made for an international convention on environmental and worker projection.150 One potential alternative is the use of retired electric vehicle batteries. These batteries can no longer be used in vehicles when capacity falls to approximately 80% of their original amount, but they may still be useful as second energy storage systems for homes, commercial facilities, and potentially the grid.151 A robust global tracking system for these batteries could help ensure their optimal use until a point of depletion, at which time they could be recycled. A complementary approach to storage is to enforce better supply and demand management through a so-called smart grid. Smart grids would regulate demand during peak use periods by, for instance, temporarily turning off or reducing demand from noncritical appliances such as air conditioners, heat pumps, and refrigerators across a range of communities. When used at scale, such a system could substantially smooth out peak demand. The combination of smart grids and batteries could help resolve problems of supply and demand.152,153

Energy Efficiency and Conservation Energy conservation is the act of reducing energy use by using less of an energy service (e.g., less driving) or using energy more efficiently (e.g., driving more efficient vehicles).3 It is estimated that only 14% of primary energy is converted into services; that is, increasing the energy efficiency at the service level (e.g., from a vehicle or heater) by 1 unit yields a reduction in primary energy input of 7 units.154 These reductions in primary energy input—whether from clean, renewable sources or from fossil fuels—offset associated risks, including ecosystem damage during production, occupational hazards, release of climatealtering pollutants, and impacts on human health. Conservation improvements that could have benefits across health, climate, and ecosystems include an economy-wide reduction in carbon intensity, improved fuel efficiency

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for transportation, distributed energy generation and smarter, optimized distribution, and improvements in building efficiency.155 A recent modeling exercise found that concerted efforts to improve efficiency of end-use energy services could lower global energy demand by 40% compared with today, thereby helping to achieve global climate goals by 2050.154 The analysis focused on improved efficiency in three key domains of energy use: thermal comfort, consumer goods, and transportation. The scenario described, though ambitious, falls within other modeled scenarios seeking to stabilize mean global temperature increase at 1.5ºC through primarily supply-side control mechanisms.

Toward Energy for Planetary Health Energy use, planetary health, and development share inextricable and complex linkages. Much of the impact of energy use comes from the extraction, gathering, processing, and combustion of two classes of fuels: biomass and fossil fuels. Approximately 35% of humanity still relies on simple burning of wood, dung, crop residues, and charcoal for their household energy needs, resulting in high levels of exposure to numerous hazardous air pollutants. The gathering of these fuels imposes time and safety burdens on households—particularly for women and girls—and, in some contexts, puts pressure on forest resources. Most significantly, the use of these fuels results in a large health burden, typically on the poor, and is estimated to contribute to between 2 and 4 million deaths per year. When these households have electricity or access to clean fuels, it is often either unreliable, of inadequate intensity, or too expensive to use for the most basic household energy needs: cooking and heating. Progress toward clean household energy is under way in many countries as part of “normal” development. Although the transitions are occurring, for the most part they are proceeding slowly and are plagued by issues of consistent supply, affordability, and continued use of traditional fuels. Placing a priority on speeding up near-complete transitions away from biomass to cleaner fuels such as electricity, LPG, ethanol, or biogas could greatly benefit human health with a minimal impact on climate. This aspirational goal affords a basic level of clean energy to all households to ensure that routine tasks do not contribute to ill health. Providing clean fuels in these contexts should be considered an important transition solution, with the ultimate goal being clean household energy, probably via electricity generated from renewable sources. Almost everyone on Earth—including many biomass users—experiences air pollution associated with the combustion of fossil fuels for power generation and for transport. The implications of this combustion are vast and have both immediate (health effects, occupational harms, and pollution of ecosystems and communities) and long-term consequences, including climate change. The impacts of climate change are already being experienced by populations around the world and are expected to grow significantly in coming decades (see Chapter 10).

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For long-term protection of planetary health, dramatic reductions in emissions of climate-altering pollutants need to occur through a broad set of diverse solutions. Many, though not all, of these transitions may turn out to have co-benefits; that is, they may be wins for both global climate and human health. Any such set of solutions will need to balance national and international agendas and consider how best to optimize between the often-competing priorities of equity, climate, health, environment, and energy. For large-scale energy production, this means increasing reliance on renewable sources of energy, including solar, wind, and hydropower while continuing, at least in the near future, to use natural gas efficiently to ensure continuous and regular supply. Where fossil fuels continue to be used, carbon capture and sequestration may mitigate some of their impacts. Regardless of energy source, a concerted effort to maximize efficiency at both the supply side and at the level of energy services is necessary. As technology advances, changes to management of the grid and electric appliances— including regulation of some appliances centrally and increased dispersal of storage and generation capacity at the household and community level—may lead to an optimal solution of energy provided by clean sources and managed to maximize efficiency. The health consequences of renewable energy are much lower in the short term than those of fossil fuels, but the full lifespan of renewable energy generation technologies must be considered carefully. Other energy sources, including nuclear power, may play a role in the future energy mix, depending on how risk perception and policy play out over the coming decades. Exploration of the global energy system reveals that, as with so many aspects of society, humanity is at a crossroads. The current energy system has profound flaws and cannot be extended into the future without devastating consequences. An alternative path is available, one that emphasizes access to clean energy for all, dramatically reduces the global scourge of air pollution, and addresses one of the greatest threats of the century, global climatic disruption. For some areas of the energy system, such as electricity generation, existing technologies for wind and solar generation are inexpensive enough to support a vision of a world dominated by renewable electricity. But there is still an enormous challenge, because current production capacity for solar PV panels and wind turbines is only a small fraction of what would be needed to produce even half of the world’s electricity from renewable energy by mid-century. Replacing oil in the transportation sector is also a large challenge, because existing technologies such as electric vehicles and hydrogen-powered fuel cell trucks are still far more expensive than existing internal combustion engine vehicles, with additional challenges of battery supplies and new infrastructure for charging or fueling stations. However, the potential to reduce air pollution, vehicle crashes, and GHG emissions through the “3 Revolutions”—electrification, IT-based shared mobility, and

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driverless vehicles—is large.156 With investment in research, development, and deployment, the global energy transformation beyond fossil fuels is feasible but will take many decades of deep commitment and global political will to achieve the necessary scale of mobilization. The choice is ours.

Authors Ajay Pillarisetti, PhD, MPH is an assistant professor of environmental health at Rollins School of Public Health, Emory University. He collaborates on household energy, health, and climate-related research and capacity building in India, Nepal, Mongolia, Ghana, and elsewhere. He develops software and hardware tools to enable household energy-related impact evaluations. Kirk R. Smith, PhD, MPH is professor of global environmental health in the School of Public Health, UC Berkeley, and holds honorary professorships in China, India, and Mongolia. He founded and ran the Energy Program at the East–West Center in Honolulu before moving to Berkeley and is now director of the Collaborative Clean Air Policy Centre in New Delhi. He was on the Executive Committee and headed the health and environment chapter of both the World Energy and Global Energy Assessments and was co-leader of the Health Chapter of the fifth assessment of the Intergovernmental Panel on Climate Change.

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138. Hoekman SK, Broch A, Liu X. Environmental implications of higher ethanol production and use in the U.S.: a literature review. Part I: impacts on water, soil, and air quality. Renew Sust Energ Rev. 2018;81:3140–3158. 139. Scovronick N, Wilkinson P. Health impacts of liquid biofuel production and use: a review. Glob Environ Change. 2014;24:155–164. 140. Sanchez DL, Johnson N, McCoy ST, Turner PA, Mach KJ. Near-term deployment of carbon capture and sequestration from biorefineries in the United States. Proc Natl Acad Sci. 2018;115(19):4875–4880. 141. Schlünssen V, Madsen AM, Skov S, Sigsgaard T. Does the use of biofuels affect respiratory health among male Danish energy plant workers? Occup Environ Med. 2011;68(7): 467. 142. Hochman G, Zilberman D. Corn Ethanol and US Biofuel Policy Ten Years Later: Am J Agricult Econ. 2018;100(2):570–84. 143. Serra T, Zilberman D. Biofuel-related price transmission literature: a review. Energy Econ. 2013;37:141–151. 144. Filip O, Janda K, Kristoufek L, Zilberman D. Food versus fuel: an updated and expanded evidence. Energy Econ. 2017. 145. Zhang Z, Lohr L, Escalante C, Wetzstein M. Food versus fuel: what do prices tell us? Energy Policy. 2010;38(1):445–451. 146. de Gorter H, Drabik D, Just DR, Kliauga EM. The impact of OECD biofuels policies on developing countries. Agric Econ. 2013;44(4-5):477–486. 147. Lindley D. Smart grids: the energy storage problem. Nature News. 2010;463(7277):18– 20. 148. Kang DH, Chen M, Ogunseitan OA. Potential environmental and human health impacts of rechargeable lithium batteries in electronic waste. Environ Sci Technol. 2013;47(10):5495–5503. 149. Richa K, Babbitt CW, Gaustad G, Wang X. A future perspective on lithium-ion battery waste flows from electric vehicles. Resour Conserv Recy. 2014;83:63–76. 150. Initiative for Responsible Mining Assurance. 2019. https://responsiblemining.net/. Accessed April 2020. 151. Hu Y, Cheng H, Tao S. Retired electric vehicle (EV) batteries: integrated waste management and research needs. Environ Sci Technol. 2017;51(19):10927–10929. 152. Fox-Penner P. Smart Power: Climate Change, the Smart Grid, and The Future of Electric Utilities, Second Edition. Washington DC: Island Press; 2014. 153. Hui L, Li H, Jiang Y. Using air source heat pump air heater (ASHP-AH) for rural space heating and power peak load shifting. Energy Procedia. 2017;122:631–636. 154. Grubler A, Wilson C, Bento N, et al. A low energy demand scenario for meeting the 1.5°C target and sustainable development goals without negative emission technologies. Nat Energy. 2018;3(6):515–527. 155. Haines A, Smith KR, Anderson D, et al. Policies for accelerating access to clean energy, improving health, advancing development, and mitigating climate change. Lancet. 2007;370(9594):1264–1281. 156. Sperling D. Three Revolutions: Steering Automated, Shared, and Electric Vehicles to a Better Future. Washington, DC: Island Press; 2018.

13 Urban Places and Planetary Health Ana V. Diez Roux, Adriana C. Lein, Iryna Dronova, Daniel A. Rodríguez, Rosie Mae Henson, Olga Sarmiento

The word city may conjure up dueling images in our minds. On one hand, it can evoke dystopian images of throngs of people wearing surgical masks as they wade through thick smog that obscures surrounding buildings. We might picture slums built of cardboard and corrugated tin, clinging to steep slopes or crammed into floodplains, without provision for clean water, sanitation, or solid waste management. We might imagine generations who live their lives isolated from nature. We might also picture sprawling metropolitan areas, navigable only by automobile and seemingly built to discourage the simple pleasures of walking or the social interactions promoted by welcoming public places. But cities are also places of hope and excitement. They can be centers of culture, education, and commerce where inhabitants walk, bike, and take public transport to work and mix and mingle in parks, greenways, and town centers. They can be centers of innovation, with eco-friendly and health-promoting buildings, food systems, and water management. Cities can have far smaller environmental footprints and be far better settings for human thriving than today’s cities. Urbanization will be the dominant global demographic trend of the twenty-first century, and the types of buildings, neighborhoods, and cities we create will go a long way in determining both the ecological footprint and the health and wellbeing of humanity. The places in which we live, work, and play (including our homes, our neighborhoods, and our cities) have a profound impact on our health. They affect our exposure to environmental hazards, determine our vulnerability to violence and disaster, shape our behaviors, and frame our social interactions. The places we build for ourselves also have 325

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significant impacts on regional ecosystems and, collectively, on global environmental trends. Regional ecosystems and global environmental trends in turn affect our health. Because the built environment, the natural environment, and population health are deeply intertwined, place-based policies and interventions can have both environmental and health consequences. For example, urban policies to promote health (e.g., strategies to increase active transportation and physical activity, improve air quality, or decrease consumption of meats and processed foods) can have important impacts on the natural environment. Analogously, policies or interventions aimed at protecting the natural environment (e.g., reducing urban sprawl and greenhouse gas emissions) can have important effects on health. Thus, interventions in one domain may have major implications for the other domains—sometimes beneficial, sometimes not. With careful planning based on systems thinking, this interrelatedness can be leveraged to optimize both sets of goals: improving health and protecting the natural environment. This is a core principle underlying planetary health.1,2 In this chapter we apply a planetary health lens to the links between urban places, the environment, and health. We review how urban places affect the environment and are in turn affected by environmental change and how urban places affect health. We then discuss a few examples of place-based policies and interventions emphasizing known or potential environmental and health co-benefits. We conclude with a review of research opportunities to advance place-based approaches to planetary health.

Urban Places and the Future of the Planet Just over half the world’s population now lives in cities, and that proportion is projected to grow to two thirds by 2050.3 Nearly all population growth during this period will take place in urban areas, particularly in low- and middle-income countries (LMICs) of Africa and Asia.4 Although megacities with populations above 10 million command much attention, most urban growth in coming decades will occur in medium-sized cities with fewer than 1 million inhabitants.5 Cities are major drivers of the global economy and account for more than 80% of global gross domestic product. Because people and economic activities concentrate in urban areas, cities are major consumers of energy, water, and other natural resources and are major producers of greenhouse gas emissions, pollutants, and waste.4 In addition, urbanization is linked to major social and cultural shifts with implications for health, quality of life, and equity. Cities are places where social interactions and connections are magnified and their effects potentiated, often with global implications.6 Cities exert important governance and policy functions that affect health and the environment in complex ways. They often have more nimble governance structures than countries, allowing them to innovate and experiment in ways that nations cannot. In addition, cities are often home to people who are progressive and globally oriented. More

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horizontal and less hierarchical modes of administration in urban governance can facilitate innovative decision making.7 Cities are also able to foster collaborative partnerships across sectors and directly engage with residents, promoting citizen participation and engagement in policy development and implementation.8 For all these reasons, cities present important opportunities for actions to leverage the interrelatedness of health and environmental systems in order to promote planetary health.

The Impact of Urban Places on Natural Ecosystems Urban places have a major impact on the global biosphere.9 A principal pathway is the expansion of urban land footprints and the consequent threats to natural habitats (via reduction or fragmentation) and loss of biodiversity.9–11 This impact is increasing as urbanization accelerates and affects new regions of the world; for example, expanding urban footprints in Africa and Asia will probably threaten previously protected high-value ecosystems.9 Cities are often located on and near especially rich land, such as along river valleys, or near biodiversity hotspots and protected natural areas. As a result, the impact of urban growth can be disproportionate to the geographic extent of expansion.9 Growing urban land footprints reduce biomass (with consequences for the global climate) and area available for agricultural production.9,12 These environmental impacts extend beyond the space occupied by urban areas themselves. For example, increasing urbanization and the reduction in available farmland create pressure to convert new land to crops and pasture in other regions, with potential adverse environmental impacts.13 Urban areas also have major impacts on hydrologic and biogeochemical cycles.9 For example, rapid urban growth has been linked to dramatic changes in precipitation at scales of hundreds of square kilometers—sometimes resulting in rainfall deficits in cities14 and sometimes resulting in increased rainfall (such as more than a threefold increase in Manila’s rainy season rainfall compared with areas 25–100 kilometers outside the city).15 In addition to reducing area available for farmland, the increase in impervious surfaces, especially in the context of greater urban sprawl, also increases exposure to floods.16 Cities are also major contributors to global climate change and pollution. This results from multiple factors, including the simple fact that population and economic activity are concentrated in cities. Cities account for more than 80% of the global gross domestic product,17 and between 71% and 76% of energy-related CO2 emissions.18 Urban expansion also contributes to global warming through loss of vegetation biomass.19 There is growing evidence that urbanization leads to complex changes in the cycling of water, carbon, aerosols, and nitrogen, with important implications for the climate system.20 Industrial activities and energy generation as well as traffic-related emissions in and around cities are major sources of air pollution.21 Approximately 80% of people living in urban areas are exposed to air that does not meet World Health Organization (WHO) guidelines.22

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In addition to the impact of urban places on global climate change and air quality, urban areas directly affect local temperatures. Cities are often warmer than their surrounding landscapes—a phenomenon known as the urban heat island effect.23 The relative warming of 1–3°C (and sometimes up to 12°C) in cities results from many factors.24 Dark surfaces such as rooftops and roadways absorb solar energy and release it as heat, heat sources such as furnaces and boilers are concentrated in urban settings, urban structures (e.g., street canyons) can trap heat and atmospheric pollutants, and cities (or particular neighborhoods within cities) often suffer from a paucity of landscape features that promote cooling, such as vegetation and water.25 The life cycles of housing and other buildings, which include design, construction, operation, maintenance, demolition, and waste management,26 affect the environment in many ways. Greenhouse gas emissions from the building sector are a leading contributor to climate change.27 When buildings are in their operational phase, their activities and primary energy use contribute 30%–40% of energy-related global greenhouse gas emissions. The construction phase of buildings alone accounts for 10% of energy consumption worldwide, and construction and demolition are important sources of solid waste. Excessive energy use, energy inefficiencies, and reliance on fossil fuels exacerbate the environmental impacts of the building sector in urban places.28,29 The need to access fresh water and dispose of wastewater and stormwater are additional important elements of the environmental impact of cities. The quality of urban water management systems has a major influence on the efficiency of resource usage and the natural environment.30,31 Over the past century global water use has been growing at more than twice the rate of population increase.32 Urban expansion, especially in dryland regions, has put increasing pressure on limited water resources, severely limiting water access both for essential residential and municipal uses and for outdoor heat mitigation, biodiversity enhancement, and irrigation.33 Management strategies and land use decisions that affect water retention and drainage are becoming increasingly vital to offset flood risks in urban areas and ensure adequate water supplies during dry periods. Urban wastewater also threatens the environment. As much as 80% of urban wastewater is released to the environment without adequate treatment.34 Although water and sanitation access are generally higher in urban than in rural areas, in many cities, especially the rapidly growing cities of LMICs, infrastructure has been unable to keep up with the rapid pace of urbanization. As a consequence, about 700 million urban residents live without improved sanitation.35 In addition to being an important contributor to urban flooding, runoff from the extensive impervious surfaces of cities is a major source of contamination of waterbodies and has important impacts on aquatic ecosystems.36 The consumption patterns associated with urban living can also have adverse environmental impacts. Although the higher population density of cities relative to rural areas should theoretically allow more efficiencies, urban residents on average consume

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more resources and energy than rural residents, nullifying that advantage. For example, cities generate extraordinary amounts of solid waste. Waste generation is growing faster than urbanization itself and is expected to double in low-income countries in the next 20 years.37 Solid waste is an important source of methane, a greenhouse gas, and waste also contributes to flooding as well as to air and water pollution. The food consumption patterns that often characterize cities, including high consumption of meats and processed foods, also have adverse environmental consequences related to land use and greenhouse gas emissions (see Chapter 5).38,39 Cities designed and organized around automobiles tend to create sprawl, with consequences for land use, traffic-related pollution, and higher greenhouse gas emissions.18,40,41 Each of these types of urban environmental impact—on land use and water resources, on biodiversity, on air quality and climate change, on heat islands, and on waste generation—represents both threat and opportunity. Because of the sheer scale of urban populations globally, the environmental impacts of continuing business-as-usual practices in cities would be devastating to the rest of the biosphere and to humanity. But for the same reason, transforming cities to be more efficient in their use of land, energy, and water and smarter in their treatment and recycling of wastes, production and consumption of food, and protection of green spaces has enormous potential to advance planetary health.

Impact of Environmental Change on Cities In addition to having major impacts on natural ecosystems, cities are highly influenced by and dependent on the regional and planetary ecosystems in which they are embedded. All of the regional and global environmental impacts of cities described in the previous section in turn have major effects on urban environments and on the lives of urban residents, creating a cycle in which cities affect broader ecosystems, and these broader ecosystems affect cities and their residents. These dynamic relationships between cities and the natural ecosystems also have major implications for population health. In this section, we review a few of the major ways in which cities are affected by regional and global environmental trends. In addition to being driven by economic and social processes, urbanization can also be strongly influenced by regional environmental factors that can drive rural–urban migration (as explored in Chapter 8). Water scarcity is often a factor, but disasters and heat can also motivate rural residents to migrate to cities. This phenomenon has been well documented in the cities of sub-Saharan Africa42 but has also occurred in other regions such as Latin America.43 Climate change has a direct and major impact on cities. One pathway is through increasing temperatures and extreme heat events. Even if greenhouse gas emissions are reduced, the proportion of the world’s population exposed to life-threatening temperatures is expected to increase from 30% to nearly 48% by 2100, with many of those exposed

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living in urban areas.44 As with other environmental vulnerabilities, marginalized groups, including poorer populations, immigrants and migrants, and nonwhite populations, are disproportionately harmed.45–47 Extreme heat also amplifies the dangerous effects of air pollution.48 The urban heat island effect can also contribute to and magnify the impact of extreme temperatures on cities. Many cities are redoubling efforts to minimize the adverse impacts of rising temperatures.25,49 Cities are highly vulnerable to environmental disasters. For example, the UN estimates that in 2014, 56% (944) of 1,692 cities with at least 300,000 residents were at high risk of exposure to at least one of six types of natural disaster (cyclones, floods, droughts, earthquakes, landslides, and volcano eruptions).50 These cities were home to 1.4 billion people. In addition, around 15% of cities were at high risk of exposure to two or more types of natural disaster; twenty-seven cities—including the megacities Tokyo, Osaka, and Manila—faced high risk of exposure to three or more types of disaster.51 Flooding is a major environmental hazard that affects many cities. Coastal cities are especially vulnerable to flooding. Roughly 2.4 billion people (40% of the global population) live within 60 miles of the coast. Urban flooding is expected to become more frequent as a result of the “triple threat” of more intense rainfall evens and storms, sea-level rise, and the loss of coastal barrier systems such as mangrove forests, coral reefs, vegetated dunes, and wetlands.52–54 The quantity of urban lands at risk for flooding is projected to double from 2000 to 2030.55,56 Preventing and reducing flood impacts has become a critical urban planning emphasis worldwide, stimulating novel and diverse strategies for water interception, detention, and storage, such as low-impact development57 and “sponge cities.”58 Management strategies and land use decisions that affect water retention and drainage are becoming increasingly vital to offset flood risks in urban areas. A dramatic example arose in 2019 when the Indonesian government announced plans to relocate its capital from Jakarta to Kalimantan, the Indonesian portion of the island of Borneo. Jakarta had been sinking for years—a result of massive withdrawals of groundwater by a growing population and of rising sea levels.59 Parts of the city were several meters below sea level, and flooding had become a regular event, with enormous human and financial costs (Figure 13.1). These problems were projected to worsen in coming decades, forcing the hard decision to relocate. However, the solution—developing a new city on a sparsely populated island with large stretches of intact rainforest—may bring its own ecological and health challenges related to deforestation and pollution. Cities around the world are also threatened by water scarcity linked to increasing demand coupled with changing environmental conditions, as illustrated by the recent water crises in cities around the world.60 This has been recently illustrated by the growing number of water crises in cities around the world. Between 2015 and 2017, Cape Town, South Africa experienced chronic urban water shortages and fears of a “Day Zero” when residential water services would be suspended due to low levels, prompted by a record

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Figure 13.1 Jakarta has suffered increasing flooding, which led to the 2019 announcement of the relocation of Indonesia’s capital. Source: Photo by Seika (Flickr), Creative Commons, license CC BY-2.0

severe drought,61 a catastrophe that was averted by rainfall in the nick of time. Water shortages are a challenge in many other areas worldwide. In India, water shortages bedevil an estimated 600 million people, and twenty-one cities have been identified as at risk of depleting their groundwater supplies by 2020.62 In many coastal cities, the combination of groundwater withdrawals and rising sea levels has led to saltwater intrusion into groundwater aquifers, threatening potable water supplies.63 Affected cities include Miami, Los Angeles, Manila, and Shenzhen. Other features of cities that directly affect natural ecosystems also affect cities themselves. Excessive waste and untreated wastewater promote disease transmission and exposure to environmental toxins. The extension of urban footprints and mismatch of residential locations, services, and jobs creates the need for long commutes and increases traffic, resulting in noise and air pollution. The growth of the built-up areas of cities reduces green spaces and vegetation. All these factors have major implications for population health.

Urban Places and Health Urban places affect health through multiple mechanisms involving the physical and social environments of cities and neighborhoods within them. Many, if not all, of the environmental impacts of cities have important implications for health in cities. Figure 13.2

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Figure 13.2 Cities and health. Conceptual model of key drivers of urban health, equity, and sustainability. Source: Diez Roux A, Slesinski S, Alazraqui M, et al. A novel international partnership for actionable evidence on urban health in Latin America: LAC-Urban Health and SALURBAL. Global Challenges. 2018;3(4):1800013.

highlights a few of the dynamic relations through which cities and their environmental consequences influence population health. Land use and transportation are two key features of cities that affect health. Urban sprawl and increased reliance on motorized transportation can reduce daily physical activity.64 Features of the neighborhood built environment, including greater land use mix (when residential, retail, educational, recreational, and other uses are co-located), separated lanes for public transportation, and features such as sidewalks and bike lanes that encourage walking and cycling, can reduce car use and promote physical activity. Greater use of motorized transportation, especially cars and buses, leads to higher levels of air pollution65 and its adverse health consequences,66 as well as greater exposure to noise and high rates of injuries and deaths (threatening both those in vehicles and pedestrians and cyclists).67 Thus, in addition to their ecosystem benefits, urban strategies that promote density and mixed land use, and that reduce reliance on automobile transportation and promote public transit, cycling, and walking, can improve health through multiple pathways including the promotion of physical activity, reduced exposure to noise and air pollution, and lower injury rates.

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Urban sprawl and fewer natural and green spaces may also have important impacts on stress, mental health, and quality of life in general. For example, long commute times are associated with more stress and adverse mental health outcomes.68,69 In contrast, access to natural environments and green space reduces stress and improved mental health (see Chapter 9).70–72 Proximity to green space encourages physical activity and reduces risk of chronic diseases.73–75 Mixed land use and welcoming green public spaces may also have important benefits for social interactions, possibly resulting in greater social cohesion with beneficial consequences for health.76 Urban diets feature greater consumption of processed, packaged, and fast foods, often high in calories, sugar, and salt, and lower consumption of fruits and vegetables compared with traditional diets.38,77,78 Factors driving these patterns include food availability, advertising, and cost; changes in cultural norms; and long work hours and commute times, leaving less time to prepare foods in the home.78 Together with more sedentary lifestyles, these dietary patterns have been linked to multiple adverse health outcomes, including the growing global burden of obesity and noncommunicable diseases.79,80 The ways in which urban places provide access to water and dispose of waste also have major health implications. An estimated 20% of the world’s urban population lacks access to improved sanitation, and as many as 50% of city residents of LMICs have been affected by water- or sanitation-related infectious illnesses.22 Solid waste in turn contributes to greenhouse gas emissions, flooding, and air and water pollution, all of which have health consequences. Urban policies that promote access to clean water and environmentally sustainable sewage treatment, while promoting reuse and recycling and reduction in the production of solid waste, will have significant environmental and health and cobenefits.81,82 A good example, the use of biofactories in Chile for wastewater treatment, is presented in Chapter 16. Rising temperatures magnified by the urban heat island effect have major implications for population health in cities. Heat exposure increases morbidity and mortality from cardiovascular, respiratory, and renal diseases.83 Older adults, children, and those who are socially isolated or economically disadvantaged are at greatest risks of adverse health effects of heat.84,85 Increases in temperature coupled with more rainfall and presence of urban standing water have helped drive the emergence of infectious diseases such as Zika and dengue as major urban health problems.86,87 Heatwaves are also associated with mental health problems and episodes of urban violence, a problem discussed in more detail in Chapters 8–10. Addressing health threats associated with rising temperatures will require broad rethinking of the ways in which buildings, neighborhoods, and cities are designed and built. But these are not just engineering challenges; civic arrangements that protect the most vulnerable citizens are also essential.

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Reimagining Our Cities: An Opportunity to Promote Planetary Health We have reviewed the many health and environmental impacts of cities, mediated through land use patterns, encroachment into natural ecosystems, and patterns of urban consumption and energy and material use. Each of these potentially negative impacts of cities also represents an important opportunity to reduce their ecological footprint. Well-managed urbanization can yield multiple environmental benefits. For example, high-density urban areas tend to have lower per capita energy use and greenhouse emissions than low-density suburban development.88 Higher-density development can also minimize the impacts of urbanization on loss of biomass, biodiversity, and land available for agricultural production.16,19 Increasing density is only one promising urban strategy. We can build better buildings with much higher energy efficiency and solar panels to generate their own power. Buildings can capture, purify, and store rainwater and incorporate vertical or rooftop gardens to reduce the urban heat island effect, produce food, and create social gathering spaces (Figure 13.3). Zoning that mixes residential, commercial, and work spaces, reliable and inexpensive mass transit, high-quality pedestrian and cycling infrastructure, and ample green spaces will reduce automobile use, create stronger community, improve mental health, and encourage physical activity. Municipal waste management systems can turn solid waste and sewage into energy, water, compost, and fertilizer, reducing harmful runoff and energy consumption and creating valuable resources for local agriculture. Overall, a combination of design elements and policies at the building, neighborhood, and metropolitan scales could collectively and dramatically reduce humanity’s total ecological footprint if used across most of our urban centers globally. In addition, many of these strategies have significant health co-benefits. Thus, cities create sustainability challenges, but they also hold the key to achieving environmental sustainability.89 In this section we focus on a few examples of policies and strategies implemented by cities that can have significant environmental and health co-benefits.

Integrated Green Urbanism Green urbanism, an urban development strategy, seeks to promote zero-emission and zero-waste urban design in order to build cities that benefit people and the planet. Key areas of focus include compact urban form, energy efficiency, environmentally friendly transportation, and urban greening.90,91 An excellent example of green urbanism is Copenhagen (Figure 13.4). Copenhagen’s remarkable urban transformation is recognized for its environmental and social benefits, with the city being considered among the greenest in the world.92–94 The most recent 2015 Municipal Plan aims to reach carbon neutrality by 2025 through green energy while simultaneously promoting “higher level of growth and quality of life.” Copenhagen’s

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Figure 13.3 Green roofs in cities, such as this one in Singapore, can provide many services, including cooling, rainwater management, pleasant places for people, habitat for flora and fauna, and even food production. Source: Photo by Jimmy Tan (Flickr), Creative Commons, license CC BY-2.0

urban policy has prioritized green and resident-oriented cities, social cohesion, quality of life, economic growth and jobs, and regional leadership.94 The plan calls for the construction of 45,000 sustainable new homes by 2027; the achievement of a distribution of traffic that is one third bicycle, one third public transportation, and at most one third car; a

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Figure 13.4 Copenhagen is widely recognized for its many sustainable and healthy features, including pedestrian and bicycle infrastructure and its environmentally sensitive waste management. Source: Pixabay

20% increase in public housing; increased social programs in disadvantaged areas; reductions of emissions and particulate pollution; and the support of health equity through improvements in mobility and environmental quality.95 Copenhagen has also implemented actions toward becoming a “zero-waste city,” a goal achieved by recycling 100% of municipal solid waste and recovering 100% of resources from waste.96 Copenhagen’s innovation in waste management encourages sustainable design, reuse, maintenance, repair, and refurbishing of resources with the goal of tripling the use of recycled material and developing technology for waste management and surveillance97,98 Many other cities across the globe are embracing green urbanism. Notable examples include Curitiba, Brazil;94 Helsinki, Finland; Paris, France; Venice, Italy; London, England; and Vitoria-Gasteiz, Spain.99

Healthier and Environmentally Sustainable Urban Transportation Driven by public and private sector innovation, cities and private firms across the globe have begun implementing novel mobility approaches that serve as alternatives to more traditional modes of travel such as the automobile, standard public buses, or metro-based public transport systems. These innovations have the potential to increase access to

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destinations, promote active travel and physical activity, decrease per capita energy consumption, lower greenhouse gas and other emissions, reduce road injuries, and decrease air pollution–related morbidity and mortality. Beyond physical and environmental health outcomes, these innovations can also have myriad impacts on mental health and wellbeing, for example by influencing social capital, community cohesion, and personal stress. Next, we describe three examples of urban mobility strategies that may have significant environmental and health co-benefits.

Bus Rapid Transit Bus rapid transit (BRT) is a bus-based transit system characterized by dedicated street lanes, traffic signal priority, fare collection off the bus, and improved stations (Figure 13.5). Globally, there are BRT lines in 168 cities: 55 in Latin America, 44 in Europe, 43 in Asia, 18 in North America, 4 in Africa, and 4 in Oceania.100 What makes BRT unique relative to rail is its modularity: Buses emulate rail in dense urban environments but can also operate like regular buses in lower-density areas. Studies of BRT impacts have shown benefits such as travel time reductions,101 densification and land use change,102 and lower

Figure 13.5 Bus rapid transit, as shown here in Curitiba, Brazil, features dedicated lanes and efficient loading and unloading. Source: Photo by Mario Roberto Duran Ortiz (Wikimedia), Creative Commons, license CC BY-SA 3.0

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motorization rates, particularly when land uses around stops support the BRT.103–105 BRT has been credited with increases in physical activity, reductions in carbon emissions, and improvements in road safety.104,106,107 Despite these positive results, BRT has also brought some challenges to urban and planetary health. For example, some studies have found that BRT users can have high exposure to pollutants including PM2.5, black carbon, and ultrafine particles.108 Because land values increase, gentrification pressures can also accompany BRT investments, decreasing housing affordability and potentially reinforcing patterns of advantage and segregation.109,110 Taken together, these mixed results highlight the importance of considering the broader system in which innovative urban transport initiatives are embedded. Concerns over these negative outcomes underscore the need to incorporate equity considerations and the voices of vulnerable communities into planning processes.

Promoting Bicycle Use Although European cities including Copenhagen, Amsterdam, and Freiburg remain leaders in bicycle use, dozens of cities worldwide, in both the Global North and South, have begun promoting bicycle use for travel and recreation. Physical activity from bicycling has important protective effects for bicyclists, including decreased all-cause mortality and reduced obesity, diabetes, cardiovascular disease, and hypertension.111–113 Bicycling for transportation also reduces pollutant emissions, an important health benefit. To encourage bicycle use, communities have focused on infrastructure projects, policies such as education and enforcement of traffic laws, programs such as community cycling days and periodic traffic exclusions, bike share programs, and promotion to make bicycling more appealing to current and potential users. Infrastructure projects focus on investments such as trails, bicycle lanes that separate users from road traffic (and pedestrians), and street devices aimed at slowing down automobiles. The benefits of these improvements for cyclists (safety, increased physical activity, lower travel times in congested conditions) and noncyclists (improved safety and lower emissions) have been well documented.114,115 Policies aimed at educating drivers and cyclists, lowering vehicle speed limits, and providing bicycle parking infrastructure tend to be effective in encouraging bicycling. Programming such as Bogotá’s Ciclovía, which turns city streets most Sundays of the year into car-free community spaces for recreation and physical activity,116 are also likely to increase bicycle use. As with BRT, bicycle infrastructure investments in many cities have focused on common destinations. Because access to these destinations is at a premium, middle- and higher-income residents tend to live in and use these spaces. By contrast, lower-income residents living in peripheral areas have limited access to this infrastructure because of physical barriers such as slopes and hillside conditions, distance to activity centers, or

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simply because they are not taken into account in the decision-making process. A parallel concern is related to gentrification induced by investments in bicycle infrastructure, with local residents expressing concern about housing price increases and displacement.117,118

Shared Vehicles, Electric Cars, and Autonomous Vehicles Revolutionary private sector–led mobility innovations are reshaping the landscape of urban transportation. Vehicle sharing (from shared bicycles to shared scooters and automobiles), cleaner vehicle propulsion systems (electric bicycles, scooters, and cars), and vehicles that drive themselves are all likely to have important impacts on urban sustainability and planetary health. Although the time horizon for implementation and full market penetration vary by innovation (some innovations such as electric motors and shared vehicles are being actively deployed globally, whereas others such as autonomous vehicles are more futuristic), these innovations have direct impacts on the urban environment and indirect impacts on the quality of urban living. Direct impacts are related to changes in fossil fuel emissions, air quality, land use change, and safety. Sharing vehicles could mean that each vehicle will be used more intensively, reducing the need for parking, although evidence suggests that some people shift from active transport and mass transit to use shared vehicles, contributing to increased traffic volume and congestion.119 Shared vehicles also bring flexibility in getting to and from mass transit modes. Vehicular electrification is likely to result in considerable air quality improvements,120 especially as electrical energy originates from renewable sources. Finally, safety is likely to be one of the greatest contributions of automated vehicles, given the heavy burden of global traffic-related mortality. Vehicular automation could contribute to smoother traffic flow and substantially lower emissions. Vehicular automation could contribute to smoother traffic flow and substantially lower emissions.121,122 A less positive impact of more efficient travel is that, without careful planning, urban areas could continue to grow in peripheral locations, expanding the footprint of cities. Similarly, because making travel easier begets more travel,123 time in motor vehicles is also likely to increase, exacerbating sedentary patterns of physical activity and its associated adverse health outcomes. Impacts of shared, electric, and autonomous vehicles can also be indirect, affecting quality of life and raising equity concerns. For example, peripheral growth means that transit service may be hard to sustain in those locations because of low population densities. Furthermore, at low densities walking and bicycling become difficult because distances are longer.124 This raises a recurring question in the field of planetary health: Who will benefit from the improvements brought by these innovations, and who will pay the costs? Will we reproduce a landscape of disadvantaged groups bearing the burdens of mobility innovations and more advantaged groups enjoying their fruits?

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Because the private sector has led many of these innovations, equity considerations have not been at the forefront. Ensuring that mobility innovations don’t create more urban sprawl and do benefit everyone equally will require a proactive approach.

Creating Healthy and Environmentally Sustainable Neighborhoods through Transit-Oriented Development Designing neighborhoods that are compact, walkable, and oriented toward mass transportation, known as transit-oriented development (TOD), is a key feature of sustainable urban planning. TOD can reduce vehicle congestion and air pollution and preserve green and open spaces.125 Higher-density and more compact urban forms have been linked to positive sustainability outcomes,126 whereas peripheral, low-density, disconnected neighborhoods contribute to higher vehicle use, less walking, weaker social connections, and lower air quality.102 More compact neighborhoods also tend to be associated with greater residential energy efficiency.127 Curitiba, Brazil is a noteworthy example of how TOD can be integrated with BRT to achieve urban sustainability. Beginning in the 1970s, Curitiba adopted an approach to municipal sustainable development that coordinated investments in BRT with land planning that promoted TOD.128,129 To support these processes, Curitiba increased urban development densities along the BRT corridors, while it actively controlled densities away from the corridors. These corridors became the structural axes along which the city developed. Currently, the city has the highest public transportation ridership in Brazil (85%) despite also having the highest number of automobiles per capita in the country.130 Curitiba’s transformation has been a model for other cities implementing BRT.131,132 Despite the attractiveness of TOD, maximizing its health benefits requires proactive urban design to alleviate some of the potential side effects of concentrated urban development, such as emergence of urban heat hotspots in densely built-up areas133 or limited access to recreational spaces and physical activity opportunities,134 particularly among specific age groups such as children and older adults.135 Specific design measures may include strategic placement of greenspaces and recreational spaces,133 with attention to age- and income-specific accessibility constraints, and enhanced opportunities for both recreational and commute-oriented walking and bicycling.134,136

Urban Strategies to Promote Healthier and More Environmentally Sustainable Urban Food Systems Cities are also using different strategies to support the development of sustainable urban food systems.137 In 2015, cities from all regions of the world signed the Milan Urban Food Policy Pact, acknowledging that urbanization and challenges in food systems are interconnected and that cities have a strategic role in the implementation of solutions.138 As of 2019, 199 cities had signed the pact, committing to integrating food policies into

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urban policies and engaging stakeholders at multiple levels to promote health and sustainable food policies.138 A major goal of the pact is to promote sustainable and resilient urban food systems. Areas of emphasis include improving governance in relation to food policy, promotion of healthy diets, social and economic equity, environmentally sustainable food production, efficient food supply and distribution, and reducing food waste. Many of these topics are explored in more detail in Chapter 5. A number of cities have launched initiatives to support the consumption of locally produced fresh fruits and vegetables, especially products produced in farm areas adjacent to cities (Figure 13.6). For example, Belo Horizonte, Brazil and Rosario, Argentina are promoting consumption of food produced by local periurban and rural farmers through policy interventions. These strategies include institutional purchases, educational campaigns, and the direct marketing of local produce to nearby urban markets.139 The promotion of urban farming supports even more local production and consumption. The city of Dakar, Senegal operates a microgarden program, providing land and supplies for microgardens for the urban poor to grow fresh and nutritious food, for household consumption

Figure 13.6 Urban farmer’s markets such as this one in New York City’s Union Square help provide a link between periurban farmers and consumers in the city, both building community and diversifying healthy food options. Source: Photo by Phil Roeder (Flickr), Creative Commons, license CC BY-2.0

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and for sale.137 The Nairobi Urban Food Bill makes it possible for city residents to legally develop urban agriculture.140 These urban farm efforts may promote health via healthier food consumption and also provide work opportunities and may increase social capital. Vertical farming, in which produce is grown indoors in highly efficient, year-round hydroponic or aeroponic systems, is another rapidly growing innovation that brings fresh local produce to urban dwellers with lower inputs of land, fertilizer, and water than traditional agriculture. Major changes in the ways in which food for urban areas is produced and distributed could bring significant environmental and health benefits. However, the full health and environmental impacts of these innovations have not yet been thoroughly investigated, and issues such as soil contamination remain a concern.141 Reducing food waste is another area of rapid innovation. In 2012, for example, Paris, France initiated a set of private sector and civil society partnerships through which the city works to safely recover and redistribute to low-income and other food-insecure populations food that would otherwise be wasted.137 Other cities are implementing similar initiatives. In Curitiba, citizens can trade recyclable materials for fresh produce originating from local family farms or can buy this produce at reduced prices. The facility collects solid waste at the same time. This program simultaneously promotes consumption of local produce, reduction of environmentally harmful waste disposal, creation of jobs, and social cohesion.139 Further evaluation of the broader health and environmental impacts of these types of initiatives is needed.

Challenges in Promoting a Planetary Health Approach to Urban Places Building the Evidence Base There is substantial empirical evidence linking features of urban places to environmental outcomes or to health. However, only rarely do investigators evaluate health and environmental outcomes as joint outcomes. Many health studies examine the environment as a possible predictor of health yet do not focus on environmental impacts as outcomes of interest per se. The environmental constructs of greatest interest are those hypothesized to have a direct impact on health or health-related behaviors. More complex environmental outcomes, such as environmental sustainability over time, receive less attention. Similarly, environmental research does not always fully explore the health implications (co-benefits) of policies to protect the environment. Scientists across multiple fields have called for a new urban science that examines cities as complex systems that affect both population health and the environment.6 The need for a systems approach that takes into account complexity, bidirectional and nonlinear

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relationships, and cuts across disciplines is a recurring theme in planetary health. Such an approach is central to generating more effective policies for healthy, livable, and environmentally sustainable cities. Advancing this science requires greater exchange and collaboration between urbanists, health scientists, and environmental scientists. It also requires transcending the rather simplistic and linear conceptual models that dominate much research today. All over the globe, cities and neighborhoods are acting to change urban places. Sometimes these policies and interventions are motivated by anticipated health or quality of life benefits. At other times, the motivators are anticipated environmental or economic benefits. Rigorous evaluation of these interventions is an underused opportunity to simultaneously evaluate health and environmental co-benefits of particular policies and interventions in order to build an evidence base for what works. Such evaluations require interdisciplinary partnerships including policymakers, academics, and practitioners.

Grappling with Implications for Equity Most urban places are characterized by deep disparities in health and socioeconomic status. Inequities in cities arise from the interplay of numerous factors including historical circumstances, social and economic processes, and racial discrimination. Inequities are manifested spatially in urban places through residential segregation by social class, race, ethnicity, or country of origin. Residential segregation, through its impact on neighborhood social and physical environments as well as access to services and resources, in turn reinforces inequities by class, race, and other factors. An especially stark manifestation of residential segregation is the presence of informal settlements or “slums” in many large cities.142 A key challenge for planetary health is the need to improve the health and living conditions of the most vulnerable (thus reducing inequities) while promoting environmental sustainability of urban places. Poorer neighborhoods are often the parts of cities most affected by environmental threats. For example, poor neighborhoods are more vulnerable to the adverse health consequences of heatwaves.143 Disadvantaged neighborhoods also tend to be in areas that are more vulnerable to flooding or landslides after excessive rains or storms144 and often have higher levels of air pollution as a result of their location more proximal to traffic or other sources.37,145 At the same time, wealthier areas consume more energy and often produce more waste and have a greater environmental impact,18 but the burden in terms of environmental consequences for health is borne by the most disadvantaged. Given these patterns, efforts to reduce the environmental impact of cities can be expected to have substantial benefits for the most disadvantaged, but the conditions under which these equity benefits are optimized is an area where more research is needed.

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There is a long tradition of place-based interventions aimed at promoting equity in cities. Examples include programs focused on improving conditions in slums, informal settlements or disadvantaged neighborhoods such as the Vila Viva program in Belo Horizonte, Brazil; the Neighborhood Recovery Program (Recuperación de Barrios) in Santiago, Chile; Kenya’s Slum Upgrading Programme; India’s Slum Networking Project; Barcelona’s law for neighborhood improvements (Ley de Barrios); and Gorbals urban regeneration projects in Glasgow, Scotland.146–151 These programs generally include components such as physical improvements in streets and housing, improved access to adequate water and sanitation, social services and job training, and participatory engagement of residents.152,153 Other examples of place-based interventions with a strong equity component include transportation initiatives such as the Metrocable in Medellín154 or the recent TransMiCable in Bogotá, aimed at improving public transportation access for disadvantaged neighborhoods located in the periphery of cities. Although some evidence exists regarding the health impacts of these interventions,155,156 assessments of environmental impacts, including broader impacts on urban footprints, climate effects, waste production, congestion, and air pollution, are limited. Important questions remain in terms of how to design these interventions so that they promote equity without increasing adverse environmental impacts. Another way in which a planetary health approach may affect equity is through unintended consequences of interventions aimed at reducing the environmental footprint of cities. One example is urban greening. It has been noted that urban greening can trigger gentrification,154,157,158 a process characterized by the influx of wealthy residents and the displacement of residents of lower means. Areas that are environmentally advantaged (e.g., neighborhoods in higher areas protected from flooding) are also becoming gentrified.159 Ensuring that well-intentioned strategies to promote environmental sustainability do not result in increased social and health inequities in urban areas is an important challenge. This may entail combining urban greening strategies with social programs aimed at promoting mixed-income housing and reducing displacements associated with neighborhood improvements. One example of a comprehensive strategy that attempted to incorporate social and environmental goals is the social urbanism strategy implemented in Medellín beginning in the 1990s.160 Social urbanism is an urban development strategy that combines physical transformations, social programs, institutional change, and participatory processes.161,162 The program resulted in improved quality of life, reductions in violence,156 and increased social capital.161 However, other environmental impacts were not systematically evaluated. Moving forward, it will be important to evaluate the equity impact of policies and interventions to promote planetary health and evaluate the planetary health impact of interventions aimed at promoting equity.

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Dissemination and Translation Innovations in building designs, transportation infrastructure, waste management, mixed use zoning, green space, and others are necessary but not sufficient to transform the world’s cities. In addition, we will need strategies for active learning from one city to another and across regions. Successful translation of evidence into action entails disseminating knowledge about the design elements, policies, and programs that are most effective in promoting health and the environment. These dissemination efforts require networks and partnerships with explicit focus on making information understandable and available to both the public and policymakers. Research on how to implement and scale up these innovations most effectively also remains an important need. Such “implementation science” is essential to learn from current efforts and inform future actions.163,164 And although technological developments and infrastructure improvements are central to transforming cities, cities are political entities, and their transformation is fundamentally a political process. Inclusive processes that engage citizens, share decision making, and address hyperlocal concerns are needed.165 So is visionary municipal leadership. The complexity of numerous neighborhoods and jurisdictions with competing interests, fragmented structures for decision making, the presence of powerful vested interests, the tension between urgent and long-term priorities, and inevitable resource limitations, all present challenges to citywide transformational change. In addition, meaningful change can take decades while political leaders, communities, donors, and investors are often operating on shorter timeframes. In meeting and overcoming these challenges, an engaged citizenry, effective, accountable governance, and committed leaders are critical. Even when there are resources and the political will to implement policies to improve health and environmental sustainability, the correct course of action is not always clear. Tradeoffs and the weighing of benefits against undesired consequences further complicate these processes. For example, movements to revitalize neighborhoods are faced with the downsides of gentrification, with possible consequences for health equity. Urban greening efforts may also exacerbate social injustice by inflating property values and triggering local gentrification.166 Efforts to promote use of public transportation may lead to unintended adverse exposures to pollutants108 or increased safety concerns. Emerging technologies (such as self-driving cars and technology-based mobility approaches) will need to be harnessed so that they are beneficial for health and the environment and promote equity. Many multipronged approaches will be needed. In these cases, thinking systemically, relying on evidence, building partnerships, and engaging the public in participatory planning approaches will be key.

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Conclusion The urban places where we spend our lives are a critical element that can be designed, constructed, and managed to improve health and protect our environment. But all too often, these places are shaped by economic priorities unrelated to the protection of health and the environment. Fortunately, many cross-city initiatives are building partnerships, networks, and coalitions to encourage a new way of envisioning cities and urban places so that they promote planetary health. Examples of these networks and coalitions include the C40 Cities, the Global Covenant of Mayors for Climate and Energy, Local Governments for Sustainability, and the 100 Resilient Cities network. The Global Covenant of Mayors for Climate and Energy is a compact comprising local leaders from 7,100 cities working to meet the targets of the Paris Agreement and promote other actions to combat climate change.167 Local Governments for Sustainability is a network of more than 1,500 towns, cities, and regions committed to promoting subnational policies and initiatives to build sustainable urban systems. Their approach spans the interrelated systems of food distribution, energy, transport, and greenways.168 Similarly, the 100 Resilient Cities network provided financial, logistical, and other support to cities to build physical, social, and economic resilience.169 Many other programs are emerging. Examples include Ecodistricts and Transition Towns, initiatives aimed at promoting and supporting healthy, equitable, sustainable, and citizen-engaged urban and neighborhood development.170,171 These networks and programs play important roles in providing platforms for city-to-city-exchange, technical assistance, and accountability. They are also vital to ensuring that city leaders are given a voice during critical talks and the formation of global agreements that have previously been dominated by national governments. Place-based interventions and policies focused on cities and neighborhoods have enormous potential to jointly promote health and environmental sustainability. They can also be leveraged to promote health equity. We are still in time to retrofit existing cities and to ensure that the urban buildup that will be occurring in middle- and low-income countries promotes health and the environment. Cities are centers of creativity, innovation, and progressivism. Indeed, it may be that well-designed cities and healthy urban living are actually a central part of the solution to the environmental challenges facing our planet. Our challenge is to use rigorous research to understand how these place-based systems are working now and how they can be nudged in a more healthful and environmentally sustainable direction. This requires engaging a range of stakeholders and the public in new ways of thinking about the links between places, health, and the environment and advocating for policies and interventions that leverage the power of places to promote health, environmental sustainability, and equity.

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Just as with our energy system, we find ourselves at a crossroads. The word city can continue to conjure up dystopian images of pollution, sprawl, slums, and roads choked with automobiles. But a different path is available in which transformed cities bring people together in healthy neighborhoods, living in efficient, green buildings, traveling in low-energy and healthy ways, and generating little or no waste, with a small fraction of the total ecological footprint of urban dwellers today. The cities of the wealthy Global North need to reorient toward this vision, and the fast-growing cities of the Global South need to strive for development patterns that lock in a positive future rather than the mistakes of the past. All cities need to strive for equity, reducing the disparities between those with means and those with little. Perhaps the greatest challenge is the challenge of imagination: to envision a different kind of future, one that is both preferable and possible and one that embodies the value of population health and a sustainable future for the planet.

Authors Ana V. Diez Roux, PhD is dean and distinguished professor of epidemiology at the Dornsife School of Public Health, Drexel University, in Philadelphia. She is an expert on the links between physical and social environments and health, with a special focus on urban areas and health inequities. Adriana Lein, MSc worked as the policy and dissemination coordinator for the SALURBAL project from 2015 to 2017. She is currently a juris doctorate candidate at the University of Washington School of Law. Her primary interests are in social policy, legislation, and employment, health, and housing law. Iryna Dronova, PhD is an assistant professor at the Department of Landscape Architecture and Environmental Planning, UC Berkeley. Her research applies geographic information systems and remote sensing data to investigate the dynamics of urban landscapes in different socioeconomic contexts. Daniel Rodríguez, PhD is Chancellor’s Professor in the Department of City and Regional Planning and associate director of the Institute for Transportation Studies at the University of California, Berkeley. His research focuses on the reciprocal relationship between the built environment and transportation and its effects on the environment and health. Rosie Mae Henson, MPH is a doctoral fellow at the Urban Health Collaborative of the Dornsife School of Public Health. Her research focuses on policy approaches to addressing health inequities in urban environments.

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Olga L. Sarmiento, PhD is a professor in the School of Medicine at the Universidad de Los Andes in Bogotá, Colombia. Her research focuses on the evaluation of community interventions to promote healthy behaviors in urban settings in partnership with local communities and stakeholders to inform policy.

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110. Wood A. Moving policy: global and local characters circulating bus rapid transit through South African cities. Urban Geogr. 2014;35(8):1238–1254. 111. Flint E, Cummins S. Active commuting and obesity in mid-life: cross-sectional, observational evidence from UK Biobank. Lancet Diab Endocrinol. 2016;4(5):420–435. 112. Furie GL, Desai MM. Active transportation and cardiovascular disease risk factors in U.S. adults. Am J Prev Med. 2012;43(6):621–628. 113. Møller NC, Østergaard L, Gade JR, Nielsen JL, Andersen LB. The effect on cardiorespiratory fitness after an 8-week period of commuter cycling: a randomized controlled study in adults. Prev Med. 2011;53(3):172–177. 114. Chen P, Shen Q. Built environment effects on cyclist injury severity in automobileinvolved bicycle crashes. Accid Anal Prev. 2016;86:239–246. 115. DiGioia J, Watkins KE, Xu Y, Rodgers M, Guensler R. Safety impacts of bicycle infrastructure: a critical review. J Saf Res. 2017;61:105–119. 116. Sarmiento OL, D’az del Castillo A, Triana CA, Acevedo MaJ, Gonzalez SA, Pratt M. Reclaiming the streets for people: insights from Ciclov’as Recreativas in Latin America. Prev Med. 2017;103:S34–S40. 117. Golub A, Hoffmann ML, Lugo AE, Sandoval GF, eds. Bicycle Justice and Urban Transformation. Abingdon, UK: Routledge; 2016. 118. Flanagan E, Lachapelle U, El-Geneidy A. Riding tandem: does cycling infrastructure investment mirror gentrification and privilege in Portland, OR and Chicago, IL? Res Transp Econ. 2016;60:14–24. 119. Bliss L. How much traffic do Uber and Lyft cause? CityLab. 2019. https://www.citylab. com/transportation/2019/08/uber-lyft-traffic-congestion-ride-hailing-cities-driversvmt/595393/. Accessed April 2020. 120. Requia WJ, Mohamed M, Higgins CD, Arain A, Ferguson M. How clean are electric vehicles? Evidence-based review of the effects of electric mobility on air pollutants, greenhouse gas emissions and human health. Atmos Env. 2018;185:64–77. 121. Stern RE, Cui S, Delle Monache ML, et al. Dissipation of stop-and-go waves via control of autonomous vehicles: field experiments. Transp Res C Emerg Technol. 2018;89:205–221. 122. Wadud Z, MacKenzie D, Leiby P. Help or hindrance? The travel, energy and carbon impacts of highly automated vehicles. Transp Res A Policy Pract. 2016;86:1–18. 123. Soteropoulous A, Berger M, Ciari F. Impacts of automated vehicles on travel behaviour and land use: an international review of modelling studies. Transp Rev. 2018;39:29–49. 124. Meyer J, Becker H, Bšsch PM, Axhausen KW. Autonomous vehicles: the next jump in accessibilities? Res Transp Econ. 2017;62:80–91. 125. Rodriguez DA, Vergel-Tovar CE. Urban development around bus rapid transit stops in seven cities in Latin-America. J Urban. 2017;11(2):175–201. 126. Wilson B, Chakraborty A. The environmental impacts of sprawl: emergent themes from the past decade of planning research. Sustainability. 2013;5(8):3302–3327. 127. Silva M, Leal V, Oliveira V, Horta IM. A scenario-based approach for assessing the energy performance of urban development pathways. Sustain Cities Soc. 2018;40:372–382. 128. Lindau LA, Hidalgo D, Facchini D. Curitiba, the cradle of bus rapid transit. Built Environ. 2010;36(3):274–282. 129. Suzuki H, Cervero R, Iuchi K. Lessons from sustainable transit-oriented cities. In: Transforming Cities with Transit. Washington, DC: The World Bank; 2013:49–94.

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130. Parra DC, Hoehner CM, Hallal PC, et al. Perceived environmental correlates of physical activity for leisure and transportation in Curitiba, Brazil. Prev Med. 2010. 131. Rosário MdR. Curitiba revisited: five decades of transformation. Archit Des. 2016;86(3): 112–117. 132. Cervero RB. Linking urban transport and land use in developing countries. J Transp Land Use. 2013;6(1):7. 133. Myint SW, Zheng B, Talen E, et al. Does the spatial arrangement of urban landscape matter? Examples of urban warming and cooling in Phoenix and Las Vegas. Ecosyst Health Sustain. 2015;1(4):1–15. 134. Lu Y, Gou Z, Xiao Y, Sarkar C, Zacharias J. Do transit-oriented developments (TODs) and established urban neighborhoods have similar walking levels in Hong Kong? Int J Environ Res Public Health. 2018;15(3):555. 135. Reyes M, Páez A, Morency C. Walking accessibility to urban parks by children: a case study of Montreal. Landsc Urban Plann. 2014;125:38–47. 136. Wang H, Qiu F. Spatial disparities in neighborhood public tree coverage: do modes of transportation matter? Urban For Urban Green. 2018;29:58–67. 137. Forster T, Egal F, Renting H, Dubbeling M, Getz Escudero A, eds. Milan Urban Food Policy Pact. Selected Good Practices from Cities. Milan, Italy: Fondazione Giangiacomo Feltrinelli; 2015. 138. Milan Urban Food Policy Pact. 2015. http://www.milanurbanfoodpolicypact.org/text/. Accessed April 2020. 139. Dubbeling M, Bucatariu C, Santini G, Vogt C, Eisenbeiß K. City Region Food Systems and Food Waste Management: Linking Urban and Rural Areas for Sustainable and Resilient Development. Bonn and Eschborn, Germany: Giz, Food and Agriculture Organization of the United Nations and RUAF Foundation; 2016. 140. Food and Agriculture Organization. Nairobi: An Act to Promote and Regulate Urban Agriculture. Nairobi, Kenya: Food and Agriculture Organization of the United Nations; 2018. http://www.fao.org/urban-food-actions/knowledge-products/resources-detail/en/c /1146758/ 141. Li G, Sun GX, Ren Y, Luo XS, Zhu YG. Urban soil and human health: a review. Eur J Soil Sci. 2018;69(1):196–215. 142. Ezeh A, Oyebode O, Satterthwaite D, et al. The history, geography, and sociology of slums and the health problems of people who live in slums. Lancet. 2017;389(10068):547– 558. 143. Klein Rosenthal J, Kinney PL, Metzger KB. Intra-urban vulnerability to heat-related mortality in New York City, 1997–2006. Health Place. 2014;30:45–60. 144. Rufat S, Tate E, Burton CG, Maroof AS. Social vulnerability to floods: review of case studies and implications for measurement. Int J Disast Risk Re. 2015;14:470–486. 145. Hajat A, Hsia C, O’Neill MS. Socioeconomic disparities and air pollution exposure: a global review. Curr Environ Health Rep. 2015;2(4):440–450. 146. Prefeitura Belo Horizonte. Vila Viva. 2018; https://prefeitura.pbh.gov.br/urbel /vila-viva. 147. Ministerio de Vivienda y Urbanismo. Programa Recuperación de Barrios: Lecciones Aprendidas y Buenas Prátcias. Santiago de Chile: Ministerio de Vivienda y Urbanismo, Programa de Recuperación de Barrios; 2009.

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148. Meredith T, MacDonald M. Community-supported slum-upgrading: innovations from Kibera, Nairobi, Kenya. Habitat Int. 2017;60:1–9. 149. Das AK, Takahashi LM. Evolving institutional arrangements, scaling up, and sustainability. J Plann Educ Res. 2009;29(2):213–232. 150. Nel·lo O. The challenges of urban renewal. Ten lessons from the Catalan experience. Análise Social. 2010(197):685–715. 151. Bansal P, Kockelman KM. Are we ready to embrace connected and self-driving vehicles? a case study of Texans. Transportation. 2018;45(2):641–675. 152. Corburn J, Sverdlik A. Slum upgrading and health equity. Int J Environ Res Public Health. 2017;14(4):342. 153. Turley R, Saith R, Bhan N, Rehfuess E, Carter B. Slum upgrading strategies involving physical environment and infrastructure interventions and their effects on health and socio-economic outcomes. Cochrane Database Syst Rev. 2013. 154. Brand P, Dávila JD. Mobility innovation at the urban margins. City. 2011;15(6):647– 661. 155. Cerdá M, Morenoff JD, Hansen BB, et al. Reducing violence by transforming neighborhoods: a natural experiment in Medellín, Colombia. Am J Epidemiol. 2012;175(10): 1045–1053. 156. Maclean K. Social Urbanism and the Politics of Violence: The Medellín Miracle. New York, NY: Palgrave Macmillan; 2015. 157. Cole H, Triguero M, Connolly J, Anguelovski I. A longitudinal and spatial analysis assessing green gentrification in historically disenfranchised neighborhoods of Barcelona: implications for health equity. J Transp Health. 2017;5:S44. 158. Dawkins C, Moeckel R. Transit-induced gentrification: who will stay, and who will go? Hous Policy Debate. 2016;26(4-5):801–818. 159. Keenan JM, Hill T, Gumber A. Climate gentrification: from theory to empiricism in Miami-Dade County, Florida. Environ Res Lett. 2018;13(5):054001. 160. Hernandez-Garcia J. Slum tourism, city branding and social urbanism: the case of Medellín, Colombia. J Place Manag Dev. 2013;6(1):43–51. 161. Calderon C. Social urbanism: integrated and participatory urban upgrading in Medellín, Colombia. In: Requalifying the Built Environment: Challenges and Responses. Gottingen, Germany: Hogrefe Publishing; 2012. 162. Sotomayor L. Equitable planning through territories of exception: the contours of Medellin’s urban development projects. Int Dev Plann Rev. 2015;37(4):373–397. 163. Damschroder LJ, Lowery JC. Evaluation of a large-scale weight management program using the consolidated framework for implementation research (CFIR). Implement Sci. 2013;8(1). 164. Kirk MA, Kelley C, Yankey N, Birken SA, Abadie B, Damschroder L. A systematic review of the use of the Consolidated Framework for Implementation Research. Implement Sci. 2015;11(1). 165. Elelman R, Feldman D, L. The future of citizen engagement in cities: the council of citizen engagement in sustainable urban strategies (ConCensus). Futures. 2018;101:80–91. 166. Wolch JR, Byrne J, Newell JP. Urban green space, public health, and environmental justice: the challenge of making cities just green enough. Landsc Urban Plann. 2014;125:234–244.

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14 Controlling Toxic Exposures Philip J. Landrigan, Terrence J. Collins, and John Peterson Myers

The modern chemical manufacturing industry originated in Europe during the Industrial Revolution in the late 1700s and early 1800s. Many products developed during those years remain foundational to modern industry, such as sulfuric acid (England, 1736), bleaching powder, or calcium hypochlorite (Scotland, 1799), and “mauveine,” the first commercial synthetic dye (England, the 1850s). Large-scale petroleum drilling began at Pennsylvania’s Drake Well in 1859, providing virtually unlimited supplies of petroleum, currently the most important chemical feedstock. As discussed in Chapter 4, chemical manufacturing has increased greatly in volume and complexity since 1950, with over 140,000 chemicals and mixtures now in commercial use. Many of these are new chemicals that never before existed on Earth. They have become ubiquitous in modern society and are found today in millions of consumer products, including soaps, shampoos, children’s clothing, toys, car seats, herbicides, insecticides, blankets, electronic goods, furniture, airplanes, food packaging, food, and baby bottles. Many synthetic chemicals have profoundly benefited human health and wellbeing. Drinking water disinfectants have drastically reduced deaths from cholera, dysentery, and other gastrointestinal diseases that once were epidemic. Antibiotics, antiparasitic agents, antifungals, antivirals, and anti-algals control infections. Chemotherapeutic agents have made possible the cure of many cancers. Chemicals are central to modern construction and transportation systems, electronics, and renewable energy. Chemical manufacture is clearly a foundational element of our civilization’s future. But widespread chemical use has also brought challenges: the uncontrolled spread of chemicals through ecosystems and organisms, including humans, across the planet, with

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harmful effects. Some of the drivers are explored in Chapter 4: the rapidly increasing scale and complexity of chemical production, the persistence of certain chemical pollutants in environmental media, bioconcentration and biomagnification of persistent chemicals in food webs, long-range transport, and concurrent Earth system changes such as climate change.1 Nearly all projected future growth in chemical manufacturing will occur in low- and middle-income countries (LMICs), where environmental safeguards and public health protection are often weak.

Chemical Pollution as a Planetary Health Problem Are the chemical contamination levels observed around the world high enough to warrant concern? Scientists initially assumed that global dilution would reduce contamination levels sufficiently to avoid harm. Three concerns challenge that assumption. First, we now know that because of biomagnification and bioconcentration, chemical concentrations in organisms can be much higher than background levels. Second, mixtures of chemicals, each at low levels, can have effects that exceed those of the individual components of the mixtures. Third, insights into mechanisms of action have revealed sensitivities once almost unimaginable, especially when exposure occurs during windows of vulnerability in early development or when toxicity is mediated by receptor action, as with endocrine-disrupting compounds.

Biomagnification, Bioconcentration, and Intensification of Effects As explored in Chapter 4, contaminants such as persistent organic pollutants (POPs) and methylmercury can bioaccumulate (increase in concentration as they move up the food web). Thus as predators eat contaminated prey and are themselves eaten by other, larger predators, bioaccumulative compounds become successively more highly concentrated in animal tissues. The result is that biomagnification can amplify POP concentrations in the tissues of top predator species such as marine mammals and humans by a factor of a million or more compared with species at the bottom of the food web.2 Physicochemical processes can also magnify concentration. For example, lipophilic contaminants concentrate in the sea-surface microlayer, a thin (1- to 1,000-micron) film on the surface of the ocean composed in part of lipids from organisms that have died. Concentrations of microlayer chemicals can be up to 500 times those of the water column.3 Microplastics floating on the ocean surface then can adsorb the lipids and associated contaminants and be ingested by higher organisms.

Mixtures Amplify Ecotoxicological Effects Toxic chemicals are rarely present in the environment in isolation but instead are found in complex mixtures whose composition varies substantially. This ubiquity of mixtures complicates the assessment of health impacts because toxicological tests have almost

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always been conducted on one chemical at a time. Although the published literature on mixture hazards is limited, there are many examples in which mixtures induce effects even if individual chemical components of the mixture are present at seemingly benign levels.4 Most regulation is based on individual chemical-by-chemical test results, which can understate risk. This narrow focus has helped allow the widespread production and use of potentially toxic pesticides such as glyphosate and neonicotinoids.5

Large Impacts from Low Doses Some manufactured chemicals can disrupt biological functions and induce harmful effects in living organisms at extremely low levels—in the parts-per-billion range, levels that were previously thought to be safe. One example of environmental importance involves the most abundant photosynthetic organism on Earth: marine phytoplankton of the genus Prochlorococcus. Experimental findings from the Atlantic, Pacific, and Indian oceans indicate that low levels of organic pollutants—levels just twice those commonly found in seawater—can reduce the expression of photosynthetic genes in these organisms, potentially reducing these organisms’ contribution of oxygen to Earth’s atmosphere.6 In higher organisms such exquisite sensitivity to low doses of pollutants is often mediated through disruption of the endocrine (hormone) signaling system.7,8 Endocrine disruption is complex; studies have shown that endocrine-disrupting chemicals (EDCs) can have different effects on health at different doses. For example, high doses of some EDCs can cause weight loss, whereas exposures to the same EDCs at one thousandth of those levels can cause morbid obesity.9 The emerging science of EDCs has upended the toxicological assumption dating from the sixteenth century that “the dose makes the poison.” Conventional safety testing of chemicals assumed that high-dose testing would reveal important adverse effects and that these could be extrapolated down to low doses, based on a dose–response relationship, to identify a point at which no effect would be seen (called the “no observed adverse effect level” [NOAEL]). The NOAEL provided the starting point for setting legal standards for chemicals. Accordingly, safety factors were applied to calculate what could be assumed to be a safe level, usually one thousandth of the NOAEL, called (in American regulatory parlance) the “reference dose.” That level was never tested directly. But because the effects of EDCs at low doses cannot be predicted from high-dose testing, this approach can be completely blind to low-dose adverse effects. As a result, established protocols for regulating chemicals are no longer tenable, suggesting the need for a different approach to safety testing for EDCs, an approach that presumes by default that dose–response curves are nonmonotonic.10 The facts that chemical production is on the rise, that both humans and ecosystems are generally exposed to mixtures, and that organisms can be exquisitely sensitive to low

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doses suggest that we may be close to crossing planetary boundaries for chemical pollutants, boundaries beyond which far-reaching impacts on humans and ecosystems could occur.11 Recent evidence of large declines in populations of insects and birds suggest that we may already have crossed one or more such boundaries.12–16

Impacts of Pollution on Ecosystems Behavioral, population, community, and ecosystem ecologists have traditionally assumed based on the remoteness of their study sites that these environments are pristine. However, this assumption ignores the ubiquity of chemical contamination in the Anthropocene era and fails to consider the powerful effects of seemingly small levels of exposure. The default assumption today should be that any site, however apparently remote and pristine, is to some degree contaminated. Few studies have examined impacts of chemical contamination on ecosystem function. However, reviews of the available research have found strong evidence that chemical pollutants can disrupt the functioning of both marine17 and freshwater18 ecosystems. Several examples are instructive: coral reefs, insects, birds, lakes, large Arctic species, and the nitrogen cycle.

Coral Reefs Several synthetic chemicals have been developed for use in sunscreens and personal care products, to protect people from ultraviolet light. One of these is oxybenzone (also called benzophenone-3). Oxybenzone can contaminate marine environments when swimmers shed it from their skin while swimming and when it is discharged in wastewater. Substantial quantities of oxybenzone are released over coral reefs each year, both directly from swimming tourists and indirectly through the wastewater stream. Popular coral reefs that attract many swimmers sustain especially high exposures. A recent study examined the effects of oxybenzone on the larval form (planula) of the coral Stylophora pistillata and on cells from this and six other coral species.19 Oxybenzone was found to have several toxic effects on the coral: transforming it from a motile state to a deformed, sessile condition; increasing coral bleaching; leading to deformed skeleton formation; and increasing DNA lesions. These effects begin to manifest at water column concentrations below 100 parts per trillion. Concentrations measured in water columns above popular coral reefs in Hawaii and the Virgin Islands dramatically exceeded this level, reaching as high as 1.4 parts per million. The toxic effects of oxybenzone compounds other risks to coral reefs from global warming and ocean acidification. Coral reef bleaching can ultimately destroy these rich ecosystems, which serve as nurseries for many species that in turn play a key role in the nutrition of coastal human populations.

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Insects Ecosystem services such as pollination are highly vulnerable to chemical pollution and especially to pesticides, as demonstrated by adverse impacts of neonicotinoid insecticides on bees and other pollinators. Many studies demonstrate short-term sublethal effects on individual bees by neonicotinoids.20 Recent research indicates that these sublethal effects may scale up to produce population extinctions over longer time scales.21 Between 1989 and 2016, across sixty-three German nature reserves, the total biomass of all flying insects declined by a remarkable 75%.12 Could landscape-scale application of pesticide mixtures have contributed? As discussed in Chapter 5, these reductions in pollinator populations can have large and direct effects on human nutrition and health.

Birds Declines in insect populations have ripple effects through ecosystems, many difficult to predict. Insect population crashes may be one factor driving reported widespread declines in insectivorous birds in Europe, including large declines in the Netherlands associated with neonicotinoid insecticide applications.22 Research in the United States, too, has linked species declines of agricultural birds with insecticide use; loss of pasture has also contributed.14 Overt toxicity and reduced prey abundance are not the only mechanisms through which pesticides threaten bird populations. Neurotoxic pesticides may also undermine birds’ ability to orient during migration.23 This could have devastating population consequences without measurable impact on direct mortality.

Lakes The ecological effects of manufactured chemicals are not restricted to POPs nor to animals at the top of the food chain. One Canadian lake provides an example, not from observational data (as is usual) but from an experiment. Over 7 years, the lake was dosed with a synthetic estrogenic chemical (an active ingredient in birth control pills) common in wastewater effluent. The chemical feminized male minnows and reduced both male and female reproductive capacity, leading to a 99% population crash of the minnows (Figure 14.1).24 These effects occurred at concentrations (5–6 nanograms per liter) well within the range permitted in treated wastewater for release back into local watersheds. Populations of the minnows’ predators also declined, not because of the direct effect of the chemical but because of the loss of their main food source, the minnow. The data also suggested that invertebrate prey of the minnow increased in response to the minnows’ decline. Thus, a toxic compound produced adverse consequences that cascaded through the local ecosystem. The global use of this ingredient in birth control pills (and of other chemicals with similar molecular effects) and its subsequent wide-scale transfer into the global environment raise concerns that the consequences of such exposure may be widespread.

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Figure 14.1 Schematic of the population responses observed in a lake food web during and after experimental addition of a synthetic estrogen (EE2). The near-extirpation of fathead minnows was probably a direct effect of the estrogen. Yellow arrows represent likely indirect effects and orange arrows represent potential direct effects. The percentages refer to changes in abundance or biomass. Source: Kidd KA, Paterson MJ, Rennie MD, et al. Direct and indirect responses of a freshwater food web to a potent synthetic oestrogen. Philos Trans R Soc Lond B Biol Sci 2014;369(1656): 20130578.

Large Arctic Species The combination of atmospheric distillation, environmental persistence, and biomagnification has led to the accumulation of extremely high concentrations of polychlorinated biphenyls (PCBs) and other POPs in Arctic marine mammals such as whales, seals, and polar bears. This has resulted in diminished immune capacity in seals and declines in reproductive capacity in a range of marine mammals.25 Although the effects of POPs on marine mammals vary in magnitude from place to place, virtually no marine mammal sampled for POPs has been without some level of contamination. And because of the global transport of semivolatile POPs via atmospheric currents and subsequent condensation in colder regions, polar areas of the globe distant from sites of chemical production, use, and disposal can carry high contaminant loads.26 The accumulation of POPs in marine mammals in the polar regions poses a major threat to the health of indigenous populations that rely on such mammals as a significant source of nutrition; human health threats from exposures to POPs range from reproductive and metabolic abnormalities to cancer.27 Climate warming in

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arctic and alpine regions is re-releasing POPs and heavy metals that have been locked into ice, further exacerbating contamination loads in wildlife and people.28,29

The Nitrogen Cycle Nitrogen is fundamental to the chemistry of proteins, enzymes, and DNA, and thus nitrogen cycling in the environment is essential to life. As described in Chapter 4, fertilizers and combustion have disrupted normal nitrogen cycling on a planetary scale. Manufactured chemicals can also affect nitrogen cycling. Some manufactured chemicals interfere with signaling between plants and nitrogen-fixing symbiotic microbes in the soil, thereby reducing nitrogen fixation.30,31 The scale of impact may be relevant only to local agricultural productivity and not to the global nitrogen balance. However, few synthetic chemicals have ever been tested for this effect. Moreover, the range of possible candidates extends far beyond pesticides known to be used in agricultural settings because of the widespread application of sewage sludge, which is replete with a wide array of bioactive compounds, including pharmaceuticals. These few examples of the ecosystem effects of toxic chemicals suggest several conclusions. First, the problem is planetary in scale. Second, impacts occur across a wide range of species, involving six of the seven kingdoms of life: Plants, Animals, Protists, Fungi, Archaebacteria, and Eubacteria. Third, chemicals can harm life through a variety of pathways and mechanisms: reproductive, neurologic, hormonal, developmental, and more. Because many of these pathways are conserved across the living world and can be found in humans, it is to be expected that human impacts align with those of other species; the pesticide that kills insects is closely related chemically to the nerve gas that kills people.

Impacts of Pollution on People Human exposure to toxic chemicals is nearly universal. The National Biomonitoring Program of the Centers for Disease Control and Prevention routinely detects measurable quantities of 200 high–production volume chemicals in the blood and urine of virtually all Americans.32 The impacts of those chemicals on human health are widespread and diverse. A full account of the health impacts of chemical pollutants on human health is beyond the scope of this chapter. Air pollution, responsible for the largest global burden of disease of all forms of pollution, is discussed in Chapter 7 and Chapter 12. Here we touch on some of the key principles of chemical exposures and the key populations at risk.

Workers Disease has followed the chemical manufacturing industry from its inception, and diseases caused in workers by manufactured chemicals have time and again provided the first indication of the hazards of synthetic chemical production. Chemical workers are at

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high risk of chemically induced disease because they are often the first to be exposed to new chemicals, and their exposures can be quite high. Cancer was one of the first human health outcomes linked to manufactured chemicals. A pioneering report of occupational disease caused by synthetic chemicals was an 1898 study of a cluster of bladder cancer cases among Swiss and German chemical workers who were occupationally exposed to synthetic aniline dyes, an early class of manufactured synthetic chemicals.33 As the chemical and dye manufacturing industry spread globally, bladder cancer followed. Leukemia caused by occupational exposure to the solvent benzene was another early consequence of chemical manufacturing.34 Like the bladder cancer caused by aniline dyes, benzene-induced leukemia followed the chemical manufacturing industry as it spread internationally. Benzene is also linked to a range of lymphomas and other blood-related lymphohematopoietic malignancies. Asbestos is a third cause of occupational cancer and is responsible for lung cancer, mesothelioma, ovarian cancer, and other malignancies.35 Each of these substances—aniline-based dyes, benzene, and asbestos—has been classified as a carcinogen by the International Agency for Research on Cancer, the cancer agency of the World Health Organization.

From the Workplace to Communities In recent decades, as chemical production has moved increasingly to LMICs, diseases caused by toxic chemicals have become increasingly common among chemical workers in these nations. Additionally, toxic chemicals often spread beyond workplaces to nearby communities and more broadly, sometimes with catastrophic effect. This repeats a pattern established in countries that industrialized early, recalling such catastrophes as dioxin contamination in Times Beach, Missouri and Seveso, Italy; PCB contamination of the Hudson River; and lead contamination near smelters in Port Pirie, Australia and El Paso, Texas. Examples of chemical contamination in LMICs include the following: • The Bhopal disaster in India, in which thousands of people were killed and injured by a massive environmental release of methylisocyanate after a chemical explosion in a pesticide manufacturing plant.36 • The continuing export each year of 2 million tons of newly produced asbestos to the world’s poorest countries, where it is used mainly in construction and leads to uncontrolled exposure of workers and community residents, including young children.37 • Informal recycling of car batteries in LMICs, resulting in both occupational lead poisoning and community “take-home” exposure to lead.38 • Environmental releases of mercury from artisanal gold mining, often in close proximity to rural villages and urban communities where pregnant women and young

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children can be exposed.39 Artisanal gold mining is the leading global source of inland freshwater mercury contamination.40 • The export to poor countries of 45 million tons per year of electronic waste. Children are often employed as pickers and sorters at e-waste recovery sites and are placed at risk of exposure to heavy metals, furans, dioxins, and other toxic chemicals.41,42

Children’s Exquisite Vulnerability People vary in their vulnerability to toxic chemical exposures based on a range of factors, such as genetic predispositions and underlying medical conditions. A key risk factor is age: Infants in the womb and young children are at special risk from exposures such as endocrine-disrupting chemicals, because they are undergoing now-or-never developmental processes controlled by the endocrine system. Effects of toxic chemicals on children’s health first began to be seen early in the twentieth century, as toxic chemicals moved out of industrial facilities and into the environment and consumer products. In the modern era, lead poisoning from exposure to lead-based paint was reported as early as 1848 in France and 1904 in Australia. The special vulnerability of the fetus was highlighted in the 1950s and 1960s, when physicians in Europe prescribed thalidomide to alleviate morning sickness among women during the first trimester of pregnancy, leading to more than 10,000 cases of phocomelia, a previously rare birth defect of the limbs. Today, in the aftermath of these episodes, it is widely understood that children and fetuses are exquisitely sensitive to toxic chemicals. According to a 1993 National Academy of Sciences (NAS) report, Pesticides in the Diets of Infants and Children, “children are not little adults.”43 The NAS report identified four differences between children and adults that contribute to children’s heightened susceptibility to toxic chemicals: • Children have proportionately greater exposures to toxic chemicals than adults. • Children’s metabolic pathways are immature, and a child’s ability to metabolize toxic chemicals is different from an adult’s. • Children’s exquisitely delicate early developmental processes are easily disrupted. Windows of vulnerability occur during critical periods in early development when exposures to even minute doses of toxic chemicals—levels that would have no adverse effect on an adult—can disrupt organ formation, increase lifelong risk of noncommunicable disease, and cause lifelong functional impairments. • Children have more future years than adults to develop diseases of long latency that may be triggered by harmful exposures in early life. Publication of the NAS report spurred increased investment in research in children’s environmental health beginning the mid-1990s. Prospective, birth cohort epidemiologic studies launched since that time have proven to be particularly important engines of scientific

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discovery and have led to recognition of multiple causal associations between prenatal exposures to toxic chemicals and low birth weight, asthma, neurodevelopmental impairment, and other ailments in both childhood and adult life. These effects play out over the course of a child’s life and even across generations, underscoring the value of a multigenerational planetary health perspective.

Endocrine Disrupters Endocrine (hormonal) disruption is a critically important mechanism of chemical toxicity that has been extensively studied in recent years. A number of manufactured chemicals are now recognized as able to disrupt hormonal signaling and thus alter development, reduce cognitive function and intelligence, and impair reproductive capacity.8 Endocrine disruption illustrates several key principles: • Large biological effects can occur at very low doses. • Toxic effects occur across multiple species, ranging from minnows to humans—illustrating that common biological pathways are shared with species across the biological world. • The timing of exposures is important. Windows of unique vulnerability in early life, determined by developmental pathways and stages, are associated with the most severe and lasting effects. Effects sustained during those periods are not limited to childhood. • Effects can occur across the lifespan. One worrisome trend, for example, is that human sperm counts in Western countries have declined significantly since the 1970s,44 falling by 50%–60% with no indication that the decline is slowing. Studies in China show similar results, with declines in sperm counts of as much as 40% over recent decades.45,46 Such trends are manifesting as reduced fertility sufficient to affect population growth rates. In a recent Danish study approximately 25% had sperm count sufficiently reduced to increase time to pregnancy and 15% were so severely impaired that it is unlikely they would be able to reproduce without fertility treatment.47 Endocrine disruption is emblematic of the far-reaching human impacts of chemical pollutants.

Why Have Toxic Chemicals Become a Major Threat to Planetary Health? Historical Origins of the Problem Commercial introduction of new manufactured chemicals has time and again preceded any prudent effort to assess their safety or toxicity, particularly efforts to examine impacts on human health. This failure to exercise due diligence makes it impossible to

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Figure 14.2 Children spraying DDT with abandon to fight the potato beetle, East Germany, 1953. Source: Bundesarchiv, Bild (Wikimedia), Creative Commons, license CC-BY-SA 3.0

know in advance which chemicals will be beneficial and which must be treated with caution. Two sequences of events have marked many historical missteps with chemicals: the enthusiastic introduction and wide dissemination of many thousands of chemicals and new products (Figure 14.3), followed by the belated discovery that some of these apparently beneficial chemicals pose unanticipated threats to human health and the environment.48 Historical examples of substances that were introduced with great fanfare, inadequately tested for safety or toxicity, and belatedly found to have caused great harm to human health and the environment include the addition of lead to paint and gasoline, the use of asbestos for insulation and fireproofing products, the use of DDT as a pesticide (Figure 14.2), the introduction of thalidomide to control nausea in pregnancy; the widespread use of PCBs in electrical transformers, the use of the synthetic hormone diethylstilbestrol (DES) to prevent miscarriage in pregnancy, and the use of ozone-destroying chlorofluorocarbons (CFCs) in refrigeration units.

Early Warnings Ignored A recurrent theme is that early warnings that new chemicals might pose hazards to human health and the environment have repeatedly been ignored. As a result, efforts to control exposures and prevent disease have been delayed, sometimes for decades. Industries with deeply vested commercial interests in protecting markets for hazardous technologies have actively opposed efforts to understand and control exposures to these materials and have denied the existence of hazards, sometimes even after their own scientists have documented such hazards. These industries have used highly sophisticated disinformation campaigns to confuse the public, and they have directly attacked physicians and environmental scientists who called attention to the risks of emerging technologies. These industry-sponsored tactics—developed during efforts to oppose control of lead, mercury, and tobacco—remain in use today with chlorinated solvents, organophosphate pesticides, chemical herbicides, endocrine disruptors, and fossil fuels.49,50

Figure 14.3 Upbeat advertisement for synthetic chemicals after World War II.

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Absence of Governance and Coherent Chemical Policy The large corporations that are responsible today for most chemical manufacture are for the most part publicly held companies. The primary legal responsibility of their officers is to maximize financial returns to investors. The inevitable consequence of this legal construct is that protection of human health and the global environment are at best secondary concerns. In the absence of enforced regulations, public health is often not protected. Unwanted materials are discharged into the environment, and the health and economic costs that result from this contamination are externalized, excluded from corporate financial accounting, and often imposed on the general public. This corporate model, with its near exclusive focus on short-term financial gain and disregard for long-term consequences or social justice, is unsustainable, unfair, and incompatible with long-term planetary health. It illustrates two core themes of the field of planetary health: • Those who benefit from environmental degradation and those who pay the costs are often very different populations, and • Quantifying the human health costs of environmental degradation is an important step in moving these costs out of the realm of vague externalities and into the realm of cost–benefit analysis and policymaking. A particularly egregious policy gap is that fewer than half of the high-production volume chemicals currently on world markets have undergone any testing for safety or toxicity, and only about 20% of these chemicals have been screened for their potential to disrupt early human development or to cause disease in infants and children. Rigorous premarket evaluation of new chemicals became mandatory only in the first two decades of the current century, and in only a few high-income countries.51–53 The absence in most countries of a coherent chemical protection policy is a root cause of the global problem of chemical pollution and toxicity. The results of this poor stewardship and lack of due diligence are as follows: • Chemicals and pesticides whose potential to harm human health and the environment were never examined have repeatedly been responsible for the episodes of disease, death, and environmental degradation described in the preceding section of this chapter; and • Little is known about the possible dangers to human health and the environment of most of the synthetic chemicals in the world today. Even less is known about the potential health effects of simultaneous exposure to multiple chemicals or about how chemicals may interact with one another in the human body, possibly causing synergistic adverse effects on health. Current examples of these challenges are shown in Box 14.1.

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Box 14.1. Recent Examples of Chemicals Introduced into Commerce and the Environment with Little or no Premarket Evaluation • Developmental neurotoxicants such as brominated flame retardants, widely used in couches, carpets, mattresses, and computers, have been shown to cause delays in brain development with loss of IQ points and attention problems.a • Endocrine disruptors such as phthalates and bisphenol A (BPA) have been implicated in neurological, endocrine, and reproductive developmental problems and obesity.b–d • Chemical herbicides, most notably glyphosate, considered by the International Agency for Research on Cancer to be “probably carcinogenic to humans.” Glyphosate use has increased by 2,500% in the United States over the past two decades, and global use is expanding rapidly. Its major application is for weed control in herbicide-resistant genetically modified food crops. It is used today on more than 90% of corn and soybean grown in the United States. The European Union has seriously considered restriction but recently granted a 5-year extension of use.e • Novel insecticides, notably the neonicotinoids. These chemicals, such as imidacloprid, are neurotoxic. They are implicated in bee colony collapse disorder. There is almost no information in the open literature on their possible human or developmental toxicity.f • Pharmaceutical wastes. With increasing pharmaceutical manufacture and use by a growing global population, pharmaceutical wastes—including metabolites excreted by people and animals—have entered ecosystems in increasing quantities. Urban wastewater is a dominant source, but pharmaceutical factories, hospitals, agriculture, and aquaculture can be major local sources. One review found evidence of more than 600 distinct pharmaceuticals in samples of surface water, groundwater, tap water, manure, soil, and other environmental media from seventy-one countries.g Because pharmaceuticals are designed to have biological effects at low doses, unintended environmental impacts—and perhaps human impacts—are to be expected.h • Nanomaterials. The nanoscale refers to the 1- to 1,000-nanometer (10–9) size range, although nanoparticles are commonly defined as particles with dimensions between 1 and 100 nanometers. Thousands of kinds of nanoparticles have been designed and created, with a wide range of uses,

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from personal care products to electronics to medications. With rapid growth of nanotechnology, nanoparticles are widely dispersed in the environment. However, toxicological testing has not kept pace with use.i,j Toxic effects may yet emerge, reprising the pattern described above. References a. Lam J, Lanphear BP, Bellinger D, et al. Developmental PBDE exposure and IQ/ ADHD in childhood: a systematic review and meta-analysis. Environ Health Perspect. 2017;125(8):086001. b. Ejaredar M, Nyanza EC, Ten Eycke K, Dewey D. Phthalate exposure and children’s neurodevelopment: a systematic review. Environ Res. 2015;142:51–60. c. Miodovnik A, Edwards A, Bellinger DC, Hauser R. Developmental neurotoxicity of ortho-phthalate diesters: review of human and experimental evidence. Neurotoxicology. 2014;41:112–122. d. Braun JM, Sathyanarayana S, Hauser R. Phthalate exposure and children’s health. Curr Opin Pediatr. 2013;25(2):247–254. e. Guyton KZ, Loomis D, Grosse Y, et al. Carcinogenicity of tetrachlorvinphos, parathion, malathion, diazinon, and glyphosate. Lancet Oncol. 2015;16(5):490–491. f. Cimino AM, Boyles AL, Thayer KA, Perry MJ. Effects of neonicotinoid pesticide exposure on human health: a systematic review. Environ Health Perspect. 2017;125(2):155–162. g. aus der Beek T, Weber FA, Bergmann A, et al. Pharmaceuticals in the environment: global occurrences and perspectives. Environ Toxicol Chem. 2016;35(4):823–835. h. Arnold KE, Brown AR, Ankley GT, Sumpter JP. Medicating the environment: assessing risks of pharmaceuticals to wildlife and ecosystems. Philos Trans R Soc Lond B Biol Sci. 2014;369(1656). i. Jeevanandam J, Barhoum A, Chan YS, Dufresne A, Danquah MK. Review on nanoparticles and nanostructured materials: history, sources, toxicity and regulations. Beilstein J Nanotechnol. 2018;9:1050–1074. j. Missaoui WN, Arnold RD, Cummings BS. Toxicological status of nanoparticles: what we know and what we don’t know. Chem-Biol Interact. 2018;295:1–12.

Absence of Toxicological Data Lack of knowledge about the possible effects of most manufactured chemicals is a pervasive problem in ecotoxicological research. The history of the discovery of CFCs’ impact on stratospheric ozone illustrates the potential consequences of this lack of information. To a significant degree, this discovery was serendipitous, the result of three separate lines of investigation: study of the global distribution of CFCs from their discovery in the mid1920s, exploration of the chemistry leading to the postulate of ozone depletion in the late 1960s and early 1970s, and detection of the ozone hole in the late 1970s and early 1980s. These three lines of investigation came together almost by accident and through

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the genius of a few minds54 and might not have happened at all. Given how many other synthetic chemicals are in widespread use, what are the chances others are today interfering with biogeochemical processes at a scale that creates planetary threats? A related unanswered question is whether additional chemicals in use today pose unrecognized hazards to human health. Figure 14.4 illustrates this concept in relation to developmental neurotoxicants. Only a handful of chemicals are known from clinical and epidemiologic studies to be developmental neurotoxicants in children, but another 200 chemicals have been shown to cause neurotoxicity in adult workers, and another 1,000 are known to cause neurotoxic effects in experimental animals.55 It is not known how many of these 1,200 chemicals, some of which are currently in wide use, may pose neurotoxic hazards to infants and children.

Figure 14.4 The extent of knowledge of neurotoxic chemicals. Of the thousands of chemicals in commerce, only a small fraction have been proven to cause developmental neurotoxicity in children, but another 200 can cause neurotoxicity in adult workers and another 1,000 are neurotoxic in experimental animals. Source: Grandjean P, Landrigan PJ. Developmental neurotoxicity of industrial chemicals. Lancet 2006;368(9553):2167–2178.

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Dr. David Rall, former director of the National Institute of Environmental Health Sciences (NIEHS), is said to have commented, “If thalidomide had caused a ten-point loss of IQ instead of obvious birth defects of the limbs, it would probably still be on the market.”56

A Planetary Health Approach to Chemicals: New Policies, New Paradigms A coherent strategy for protecting populations and the ecosphere against the health hazards of manufactured chemicals must be based on policies that are health-protective and calibrated to protect the most vulnerable: fetuses, young children, and pregnant women, as well as the most vulnerable nonhuman species. The linchpins of such a chemical safety policy include the following: • Testing chemicals now in use: a legally mandated and strictly enforced requirement to test the safety and toxicity of chemicals already in commerce, prioritizing those in widest use with greatest likelihood of toxicity. As described below, the toxicity testing paradigm currently in use must be redesigned to optimize the detection of lowdose effects, effects that are often mediated through endocrine disruption. • Premarket testing of all new chemicals: mandatory premarket evaluation of all new chemicals using a tiered approach that directs greatest scrutiny to chemicals intended for wide use in consumer products and thoroughly examines low-dose adverse effects. • Postmarket surveillance: monitoring the impact of chemicals on human and environmental health after they have entered markets using laboratory, in-field, clinical, and epidemiologic methods. Such postmarket surveillance is an essential complement to premarket toxicity testing and a key safeguard analogous to that routinely conducted for pharmaceuticals. By detecting ecological and human health effects of chemicals that were overlooked or undetected in premarket assessments before they grow to massive proportions, postmarket surveillance can decrease the frequency of chemical catastrophes such as the thalidomide disaster or the atmospheric ozone hole. Additionally, postmarket surveillance yields direct evidence of the effects of chemicals on human health and the environment and provides information on the effectiveness of policy interventions. • Mandatory cleanup: policies to clean up legacy chemicals, prioritizing sites with the greatest potential for human and ecosystem harm and applying the polluter-pays principle whenever appropriate. • Green and sustainable chemistry: development of a vibrant multidisciplinary field that addresses all technical, legal, and regulatory, economic, cultural, and political barriers to a sustainable chemical enterprise. Green chemistry is discussed in detail below.

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Chemical Testing: New Policy Frameworks To address the crisis of uncontrolled chemical exposure, in recent years governments have begun to promulgate chemical safety policies. These policies center on mandatory toxicity testing. Two leading examples are the REACH legislation in Europe and the 2016 amendments to the Toxic Substances Control Act in the United States. The European Union enacted the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulation in 2007. REACH requires the chemical industry to conduct extensive safety testing of new chemicals before the chemicals can come to market. Companies must submit their testing information to the European Chemical Agency, which in turn uses the information to determine whether it is safe to allow a chemical to enter consumer products and to craft regulations that protect the health of children. Under REACH, hazardous chemicals that are still allowed in consumer products in the United States have been banned in Europe. There is some evidence that REACH has been effective in reducing the use of dangerous chemicals such as plasticizers.57 The European Chemical Agency is also developing a public database that will make information on hazardous chemicals widely accessible to the general public. One potential shortcoming of the REACH regulation is the lack of provision for testing mechanisms of toxicity, such as endocrine disruption, that follow low-dose or low-concentration exposures. Following the lead of the European Union, a number of countries (including Japan, Norway, Mexico, Argentina, and Australia) are examining more closely the potential harm a chemical may cause before permitting it to enter markets. If there is not enough scientific evidence that a chemical will not harm a child’s development, the chemical is banned in those countries. In the United States, after many years of effort by public health, environmental, and human rights groups, and despite concerted opposition from the chemical industry, bipartisan chemical safety legislation was enacted in 2016 and signed into law by President Barack Obama. This new legislation, titled the Frank R. Lautenberg Chemical Safety for the 21st Century Act, updated the 1976 Toxic Substances Control Act, whose deficiencies had been widely noted.58 Despite some shortcomings, the Lautenberg Act became one of the nation’s strongest environmental laws.53 The law: • Requires that the Environmental Protection Agency (EPA) evaluate existing chemicals for safety and that it do so within clear and enforceable deadlines. • Requires that the EPA establish a process to determine which existing chemicals it will prioritize for evaluation. • Requires that the EPA use new risk-based standards to evaluate the safety of chemicals. This requirement mandates that the EPA consider only the hazard of a chemical and not risk–benefit or the costs of protective action. Under this standard, chemicals are evaluated to determine whether their use poses an “unreasonable risk.”

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• Requires that the EPA take action to address unreasonable risks within 2 years, or 4 years if an extension is needed. • Requires that the EPA make an affirmative finding on the safety of a new chemical or significant new use of an existing chemical before it is allowed to enter the marketplace. • Provides for increased public access to information on chemical safety. • Provides consistent funding for the EPA to carry out its new responsibilities. In the year after the passage of this act, the newly elected Trump administration moved to impede the enforcement of this and other environmental laws. Chemical regulation in the United States will continue to be subject to pitched political debate.

High-Throughput Toxicity Testing of Chemicals: Promises and Pitfalls In the context of new chemical safety legislation, much attention has been directed in recent years to the development of new, high-throughput technologies for toxicological screening. These approaches incorporate innovations such as exposure modeling, sensors, biomonitoring, omics technologies, novel computational methods, big data mining, and bioinformatics as well as the integration of toxicological findings with genomic and health outcome data.59 These methods are more efficient and less costly than traditional whole-animal testing and therefore permit large numbers of chemicals to be evaluated fairly rapidly. Moreover, they spare the use of animals in toxicity testing. The EPA and NIEHS have promoted their development through the “Tox 21” program.60 A shortcoming of high-throughput toxicity screening protocols is their inherent insensitivity to low-dose and endocrine-mediated effects. Unless they incorporate celland whole organism–based assays that are specifically designed to detect these effects, high-throughput testing protocols cannot detect low-dose effects mediated through disruption of endocrine signaling or other receptor-based effects. Detection of such complex effects requires whole organism testing, or in some instances evaluations undertaken in ecological systems.59

The Need for a Fundamentally New Chemical Testing Paradigm Effective detection of low-dose toxicity including toxicity mediated through endocrine disruption requires thorough revamping of the current regulatory testing paradigm. Current toxicity testing protocols start with a high dose of a chemical, move down progressively through lower doses until a NOAEL is detected, and then set a reference dose several orders of magnitude below that. A more sensitive and health-protective testing regimen would start at a low dose, increase the dose up to a lowest observed adverse effect level

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(LOAEL), and set the reference dose accordingly. This low-dose to high-dose strategy is much better able than the current testing regime to detect nonmonotonic low-dose toxicity, including toxicity mediated via endocrine disruption, because it is based on detecting toxic effects at low doses. Such low-dose exposures reflect the current reality of chemical exposures in developed countries, especially exposures of vulnerable populations such as infants, children, and pregnant women. An example of the needed innovative testing approach is the Tiered Protocol for Endocrine Disruption (TiPED) protocol, developed through collaboration between green chemists and environmental health scientists.59 TiPED features five tiers of testing that include in silico evaluation, high-throughput screening, and cell- and whole organism–based assays. TiPED is designed to measure not only potential hormone-like or hormone-inhibiting effects of chemicals but also the many possible interactions and signaling sequelae at diverse cell-based receptors. Such approaches, implemented as early as possible in the process of chemical development, should enable safe, sustainable chemical manufacturing.

Transparency and Public Disclosure A growing consensus in much of the world holds that people have the right to information relevant to their health and wellbeing. As explored in Chapter 17, this right to know extends from medical records to the contents of food and consumer products, and to potentially hazardous environmental and workplace exposures. Specific instances of right-to-know include sharing information on chemical toxicity with occupationally exposed workers, with subjects in research studies, with consumers, and with members of the public when biomonitoring or environmental monitoring yields information pertinent to them. Right-to-know laws regarding chemical exposures were promulgated in the United States at federal, state, and local levels beginning in the 1980s and have been credited with helping to reduce toxic exposures.61,62 It is important to recognize that information on toxic exposures can be complex and ambiguous, and because many members of the public have low science and health literacy,63 misunderstanding can easily occur.64 Accordingly, information on chemicals should be shared not only transparently but also in ways that take account of public perceptions, respectfully and reciprocally engage community members, and use principles of adult learning.65,66

Green Chemistry: The Promise and the Challenge The Promise of Green Chemistry Solutions to the planetary problem of toxic chemical pollution will require a fundamental transformation of chemical manufacturing to a system based on the principles and practices of green chemistry. The changes needed to achieve such a transformation go beyond a mere technical evolution in which hazardous products and processes are reduced and

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eliminated. It entails a fundamental reorientation of chemistry education and a broader cultural conversion within the entire field of chemistry that moves beyond narrow consideration of the properties of new molecules and their economic viability and instead prioritizes the welfare of the future over expediency and near-term profits. The core of green chemistry involves consideration and avoidance of the potential negative impacts on humans, ecosystems, and society of new chemicals from the earliest stages of their design and development. It takes special note of the potential of new chemicals for low-dose toxicity mediated by mechanisms such as endocrine disruption, and it avoids new products that will persist in the environment or in living organisms. The goal of such wide-ranging assessment of potential hazards is to create safe, nontoxic materials and technologies and thus prevent future health and environmental catastrophes while building a sustainable chemical economy. Green chemistry requires insights and knowledge from many fields of study and thus rests on cross-disciplinary collaborations between chemists, environmental health scientists, toxicologists, ecologists, and health professionals.67 The EPA defines green chemistry as “the design of chemical products and processes to reduce and eliminate the use and generation of hazardous compounds.” The foundational equation of green chemistry is that Risk = Exposure × Hazard.68 Green chemists seek to reduce the hazard component of the risk equation by designing alternative products and processes that ideally are devoid of any hazard to replace hazardous incumbents, new products that are hazard free, and technologies that can safely mitigate toxic chemicals considered to be too valuable to abandon, such as by containing or destroying the toxic chemicals before they are released to the ecosphere. A common formulation of the standard principles of green chemistry appears in Box 14.2.

Green Chemistry in an Ecological Context Our civilization interacts with the ecosphere in terms of the matter flows that maintain it—a model that pertains not only to chemicals but to much of human activity (Figure 14.5). Each day, many tens of millions of tons of matter are extracted from the ecosphere as feedstocks for the human economy (blue arrow). Inside the economy, these are transformed into economically valuable products, which then cycle within the economy until their value has been extracted (gray arrow). Then the economically spent matter is ejected back to the ecosphere (red arrow). In broad strokes, the technical sustainability challenges of the chemical enterprise are associated with the magnitudes and properties of these matter flows. It is the business of green and sustainable chemistry to help bring these flows onto trajectories that help to secure a sustainable civilization. Public policy can help in different ways in promoting solutions for each arrow.

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Box 14.2. Twelve Principles of Green Chemistry 1. Prevention It is better to prevent waste than to treat or clean up waste after it has been created. 2. Atom Economy Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product. 3. Less Hazardous Chemical Syntheses Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment. 4. Designing Safer Chemicals Chemical products should be designed to affect their desired function while minimizing their toxicity. 5. Safer Solvents and Auxiliaries The use of auxiliary substances (e.g., solvents, separation agents) should be made unnecessary whenever possible and innocuous when used. 6. Design for Energy Efficiency Energy requirements of chemical processes should be recognized for their environmental and economic impacts and should be minimized. If possible, synthetic methods should be conducted at ambient temperature and pressure. 7. Use of Renewable Feedstocks A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable. 8. Reduce Derivatives Unnecessary derivatization (use of blocking groups, protection and deprotection, temporary modification of physical and chemical processes) should be minimized or avoided if possible, because such steps require additional reagents and can generate waste. 9. Catalysis Catalytic reagents (as selective as possible) are superior to stoichiometric reagents. 10. Design for Degradation Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment. 11. Real-Time Analysis for Pollution Prevention Analytical methods need to be further developed to allow for the real-time, in-process monitoring and control before the formation of hazardous substances. 12. Inherently Safer Chemistry for Accident Prevention Substances and the form of a substance used in a chemical process should be chosen to minimize the potential for chemical accidents, including releases, explosions, and fires. Source: Anastas PT, Warner JC. Green Chemistry: Theory and Practice. Oxford, UK: Oxford University Press; 1998.

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Figure 14.5 A schematic of matter flows that support the operation of civilization, based on ideas of Herman Daly.

When chemists engage, at the blue entry arrow, they focus on optimizing extractive processes. Expansion of public and private investment in renewable energy research and implementation of key technologies and practices would help redirect resource extraction toward sustainability. The gray cycling arrow is where new compounds are discovered or invented, studied for their properties, formulated into appropriate products for the marketplace, and circulated in the economy until their value is dissipated. At this stage, chemists must focus on detecting and avoiding harmful chemicals and on designing substances that are benign—including the integration of low-dose toxicity testing—and easily broken down or recycled. Persistent molecular compounds are of particular concern. Because these compounds decompose little or not at all in natural environments, they are to be avoided wherever reasonable or managed effectively when necessary. Finally, few chemists work to improve the sustainability parameters of the red exit arrow. Nevertheless, if in the limit every toxic chemical could be destroyed before release

382  Planetary Health: Protecting Nature to Protect Ourselves

to the ecosphere—an unattainable ideal that nevertheless provides aspirational and directional guidance for research and development—a significant portion of all chemical sustainability challenges would simply disappear.

Authors Philip Landrigan, MD, MSc is a pediatrician and epidemiologist. He is professor of biology and director of the Program in Global Public Health and the Common Good at Boston College. He is a member of the U.S. National Academy of Medicine. For four decades, Dr. Landrigan has been a leader in environmental and occupational health. His early studies of lead poisoning demonstrated that lead is toxic to children even at very low levels and contributed to the U.S. government’s decision to remove lead from paint and gasoline. From 2015 to 2017, Dr. Landrigan co-chaired the Lancet Commission on Pollution & Health, whose report found that pollution causes 9 million deaths annually and is an existential threat to planetary health. Terrence (Terry) J. Collins, PhD, Hon FRSNZ is the Teresa Heinz Professor of Green Chemistry and director of the Institute for Green Science at Carnegie Mellon University in Pittsburgh, Pennsylvania. He is the lead inventor of TAML and NewTAML activators—smallmolecule, functional replicas of the peroxidase enzymes that outperform the enzymes to provide new approaches to water purification and other applications—and has received more than twenty academic and public awards, published more than 200 articles, and given more than 600 public lectures. John Peterson (Pete) Myers, PhD is board chair and chief scientist of Environmental Health Sciences, a science-based nonprofit located in Charlottesville, Virginia. He also holds a position as adjunct professor of chemistry at Carnegie Mellon University. Myers has worked on science, policy, and communication related to endocrine disruption since 1990, and in 1996 he co-authored Our Stolen Future with Theo Colborn and Dianne Dumanoski. He has received multiple public awards for this work, including the Laureate Award for Distinguished Public Service from the Endocrine Society.

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29. Miner RK, Campbell S, Gerbi C, et al. Organochlorine pollutants within a polythermal glacier in the interior Eastern Alaska Range. Water. 2018;10(9). 30. Ahemad M, Saghir Khan M. Pesticides as antagonists of rhizobia and the legumerhizobium symbiosis: a paradigmatic and mechanistic outlook. Biochem Mol Biol. 2013;1:65–75. 31. Fox JE, Gulledge J, Engelhaupt E, Burow ME, McLachlan JA. Pesticides reduce symbiotic efficiency of nitrogen-fixing rhizobia and host plants. Proc Natl Acad Sci U S A. 2007;104(24):10282–10287. 32. CDC. National Report on Human Exposure to Environmental Chemicals. 2019. https: //www.cdc.gov/exposurereport/. Accessed April 2020. 33.

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42. Grant K, Goldizen FC, Sly PD, et al. Health consequences of exposure to e-waste: a systematic review. Lancet Glob Health. 2013;1(6):e350–e361. 43. Committee on Pesticides in the Diets of Infants and Children. Pesticides in the Diets of Infants and Children. Washington, DC: National Academies Press; 1993. 44.

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62. Bennear LS, Olmstead SM. The impacts of the “right to know”: information disclosure and the violation of drinking water standards. J Environ Econ Manag. 2008;56(2):117–130. 63.

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15 A New Economics for Planetary Health Will Evison and Sam Bickersteth

The Economic Game Has Changed; Now the Rules Need To In the early days of industrialization, the global economy was tiny relative to the biosphere. The demands the economy placed on the biosphere—use of resources and assimilation of wastes—were similarly small and in many cases would barely register at a global scale (Table 15.1). Today’s global economy is huge (Figure 15.1). Its demand for resources and production of waste significantly exceeds the sustainable carrying capacity of our planet. The simple idea that current levels of human production and consumption exceed the sustainable carrying capacity of the planet has been well articulated through the work of the Global Footprint Network (GFN) using a composite measure of human ecological footprint referred to as ‘global hectares.’ Each year Earth Overshoot Day marks the date when humanity has exhausted nature’s budget for the year. For the rest of the year, we are maintaining our ecological deficit by drawing down local resource stocks and accumulating carbon dioxide in the atmosphere. According to the GFN’s methodology, humanity first exceeded the earth’s annual carrying capacity in 1970. Earth Overshoot Day was estimated at December 29 in 1970, implying that humanity needed just slightly more than one Earth to sustain its needs and wants in the year. By 2018, humanity needed 1.7 Earths and Earth Overshoot Day had moved to August 1.1

387

Table 15.1. Economic, Pollution, and Natural Resource Use Statistics Then and Now Then (year)

Now (year)

% Change

GDP (inflation adjusted, 2011 $)a

Global Measure

$1.2 trillion (1820)

$108 trillion (2015)

+10,800%

Paved or built-up areab

2,200 km2 (1800)

59,500 km2 (2016)

+2,603%

Area under agriculture (crops and pasture)b

13.4 million km (1800)

48.7 million km (2016)

+362%

Number of livestock (cattle, sheep, goats, and pigs)c

1,349 million animals (1890)

4,667 million animals (2014)

+346%

Annual plastic productiond

None (1800) 2 million tons (1950)

381 million tons (2015)

— +19,050%

Annual fossil fuel energy output (coal, oil, and gas)e

97 terawatt-hours (1800) 5,972 terawatt-hours (1900)

132,052 terawatt-hours (2016) 132,052 terawatt-hours (2016)

+135,824% +2,211%

Annual carbon dioxide (CO2) emissions (from coal, oil, gas, cement, flaring)f

2

2

29 million tons of CO2 (1800) 35,844 million tons of CO2 (2013) +122,188% 1,958 million tons of CO2 (1900) +1,831%

Annual material use (excluding fossil fuels) (biomass, construction minerals, ores)g

6,149 million tons (1900)

55,174 million tons (2009)

+897%

Annual volume of solid waste producedh,i

110 million tons (1900)

1,460 million tons (2010)

+1,327%

102.4 million km2 (1800)

29.9 million km2

–71%

343 million km2 (1700)

55 million km2

–86%

100% (1700)

10% (2010)

–90%

Remaining land wilderness area (excluding Antarctica)j,k Remaining marine wilderness areal Biomass of large predatory fishm

a. Roser, M. Economic growth. Our World in Data. 2017. https://ourworldindata.org/economic-growth. b. Goldewijk KK, Beusen A, Doelman J, Stehfest E. New anthropogenic land use estimates for the Holocene; HYDE 3.2. Earth Syst. Sci. Data Discuss. doi:10.5194/essd-2016-58, 2016. c. Data for all livestock from 1890 to 1950 are sourced from the HYDE Database (History Database of the Global Environment), published by the PBL Netherlands Environmental Assessment Agency. Available at http://themasites.pbl.nl /tridion/en/themasites/hyde/landusedata/livestock/index-2.html. Accessed October 12, 2017. d. Geyer R, Jambeck JR, Law KL. Production, use, and fate of all plastics ever made. Sci Adv. 2017;3(17):e1700782. e. Smil V. Energy Transitions: Global and National Perspectives. Santa Barbara, CA: Praeger; 2016. f. Boden TA, Andres RJ, Marland G. Global, Regional, and National Fossil-Fuel CO2 Emissions. Oak Ridge, TN: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, US Department of Energy; 2017. g. Krausmann F, Gingrich S, Eisenmenger N, Erb KH, Haberl H, Fischer-Kowalski M. Growth in global materials use, GDP and population during the 20th century. Ecol Econ. 2009;68(10):2696–2705. h. Hoornweg D, Bhada-Tata P, Kennedy C. Environment: waste production must peak this century. Nat News. 2013;502(7473):615–617. i. Kaza S, Yao LC, Bhada-Tata P, Van Woerden F. What a Waste 2.0: A Global Snapshot of Solid Waste Management to 2050. Washington, DC: World Bank; 2018. j. Goldewijk K, Beusen A, van Drecht G, de Vos M. The HYDE 3.1 spatially explicit database of human-induced global land-use change over the past 12,000 years. Glob Ecol Biogeogr. 2011;20(1):73–86. k. Watson JEM, Venter O, Lee J, et al. Protect the last of the wild. Nature. 2018;563:27–30. Authors’ conservative estimate for 1800 calculated by taking the ratio of total agricultural land area to human disturbed land area in 2009 (48.7 million km2/99.8 million km2 = 0.49) and applying the inverse of this ratio to total agricultural land area in 1800 (13.4 million km2/0.49 = 27.3 million km2) and subtracting this from the global land area (129.7 million km2 – 27.3 million km2 = 102.4 million km2). l. Jones KR, Klein CJ, Halpern BS, et al. The location and protection status of Earth’s diminishing marine wilderness. Curr Biol. 2018;28(15):2506–2512.e3. Authors’ estimate minus conservatively assumed 5% of global oceans directly affected by people in 1700 (95% * 361.1 million km2 = 343 million km2). m. Myers RA, Worm B. Rapid worldwide depletion of predatory fish communities. Nature. 2003;423:280–283.

A New Economics for Planetary Health  389

Figure 15.1 A representation of how the relationship between the economy and biosphere has changed since the dawn of the industrial age.

In 2009, a group of Earth system and environmental scientists proposed a new framework of “planetary boundaries” in a bid to define a “safe operating space for humanity” as a precondition for sustainable development.2 The framework is based on scientific evidence on the drivers of global environmental change and their interaction with critical Earth system processes such as the nitrogen cycle, the freshwater cycle, and climate regulation processes. As shown in Figure 15.2, the scientists concluded that two of the nine boundaries have already been crossed and two more are in the “zone of uncertainty,” where the risk of abrupt environmental changes begins to increase. It would be wholly wrong to ignore the fact that the sustained economic growth of the past two centuries has delivered huge advances in material wellbeing for the majority of people in the majority of places. Solutions to global challenges that once seemed insurmountable, such as ending hunger and extreme poverty and eradicating the worst infectious diseases, are now in sight, largely as a result of that sustained economic growth. But as the preceding section clearly illustrates, as a global society we have a problem: We have achieved all this, at least in part, by living beyond our environmental means. Such a situation cannot persist indefinitely without serious, perhaps even catastrophic consequences for humanity. We must find a way to transition to an economic system that retains the economic-wealth-creating and poverty-reducing powers of our current system while avoiding its unwanted side effects, notably its unsustainable destruction of the environment.

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Figure 15.2 The status of the nine planetary boundaries. Source: Adapted from Steffen W, Richardson K, Rockström J, et al. Planetary boundaries: guiding human development on a changing planet. Science. 2015;347(6223):1259855.

How Did We Get Here? Is Economics to Blame? Deficiencies in economic theory are not the sole or even the principal reason that we find ourselves in today’s challenging environmental situation. For starters, the majority of economic theory is descriptive (“positive” economics), attempting to enhance our understanding of cause and effect in the economy as a whole or to explain the behaviors and interactions of specific economic actors. Even in the realm of economic policy recommendations, it’s questionable how much fault can be ascribed to the economists themselves.

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After all, many disciplines seek to influence the actions of governments; should we fault economists because their ideas and theories happened to be the most persuasive on offer to help address the problems of the day? Probably not. However, just as societies change over time, so do the biggest problems they face. And so must the theories to explain them and the recommendations to fix them. The relationship between society and the environment has also changed radically over time. As well as adapting to reflect a changing society, economic theories must be radically expanded to incorporate findings from environmental science and ecology if they are to provide suitable prescriptions for the most pressing problems of today. Although economics is not the enemy of planetary health, economic dogma is. Dogmatically sticking with economic tools designed in a previous age to address a different set of problems presents a very real threat to planetary health. Before we get on to the many ways economics can help achieve planetary health, let’s explore a few of the big economic ideas from previous eras in an effort to answer the question “how did we get here?”

Guided by an Invisible Hand? Regarded by many as the father of modern economics, Adam Smith (1723–1790) is best known for introducing the notion of “the invisible hand,” which, so the theory goes, guides people and firms to deliver socially optimal outcomes even when they are acting based on self-interest, as long as they are operating in competitive markets with perfect information and freely adjusting prices. “It is not from the benevolence of the butcher, the brewer or the baker that we expect our dinner,” Smith wrote in The Wealth of Nations in 1776, “but from their regard to their own self-interest.” Economists have frequently cited Smith’s work in support of unfettered free markets: that many individual firms in the pursuit of profits, led as if by an invisible hand, do what is best for humanity, and hence that government intervention should be limited. Of course, we now know of the myriad ways in which markets alone often fail to deliver socially (and environmentally) optimal outcomes. One of the key sources of failure is externalities: consequences of economic activity that affect other parties but that are not reflected in market prices. For example, the costs of respiratory disease that results from burning diesel fuel are not reflected in the market price of diesel fuel, nor do palm oil prices capture the costs of lost biodiversity when tropical forests are cleared for palm oil production. Externalities occur in the presence of imperfect information or imperfect markets—and these are ubiquitous.3 Although externalities may have been unimportant when Adam Smith was writing in the 1700s, their importance has grown much as the economy has grown, which is to say exponentially. Today, externalities are the single greatest source of our environmental problems.

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Three Factors or Two? Or Simply Too Few? From Smith onward the so-called classical economists regarded economic productivity as a function of three interacting factors: land, labor, and capital. This three-factor model recognized the importance of land to production and in some variants even acknowledged the role of natural resources beyond land, such as coal. The amount of land in particular was seen as a key constraint on growth, because at the time it wasn’t clear how any more food could be generated from a single unit of land. However, somewhat problematically, the model assumed that land (and by extension natural resources) was “fixed.” Land could not be degraded, and no amount of resource use would reduce the quantity available to future generations. Much like assuming away externalities, this simplifying assumption about land, water, and other natural resources held in many contexts in the 1700s, when resource demands from industry were relatively modest, but it would be a very poor assumption in the context of today’s economy. Fortunately, the three-factor model has been significantly updated since the 1800s. Unfortunately, in its first major overhaul by the neoclassical economists of the early 1900s it took a major step backward—at least as far as representing interactions between the economy and environment is concerned—when three factors were reduced to two. You guessed it: labor and capital. In fact, around the turn of the last century, concern about resource availability all but disappeared from mainstream economic theory. Figure 15.3 shows the leading macroeconomic metaphor of the era (still a staple of most Economics

Figure 15.3 The classical economic circular flow diagram.

A New Economics for Planetary Health  393

101 courses), the income–expenditure cycle or simply the circular flow diagram. In this depiction of the economy, the potential for depletion of natural resources is completely absent in a seemingly endless circular exchange of labor, income, and goods. The impression that neoclassical economists are optimistic about natural resources isn’t based just on their absence from a simple conceptual diagram. Neoclassical theories of resource pricing, resource substitution, and technological change assert that even nonrenewable natural resources are essentially inexhaustible. Perhaps surprisingly, there is empirical evidence supporting this assertion for certain basic traded commodities.4 However, there are important caveats to these findings. First, at a time of state change, the past is not necessarily a reliable guide to the future. Second, and probably more importantly, there is ample evidence that complex natural resources such as soil, biodiversity, fresh water, and fish stocks can be exhausted, and because of the more complex ways they provide benefits to people, they can also be degraded in ways that commodity resources cannot (see for example WWF’s Living Planet Report5 ). Shades of neoclassical economics have defined the Western economic orthodoxy for most of the past century, and the influence of its ideas on economic policy would be hard to overstate. That a school of economic thought that pays such scant regard to ecological systems has dominated political economy for so long helps explain why we are where we are.

To Grow, or . . . to Grow? That Is the Question. Much ink has been spilled about the problems with the endless pursuit of growth in modern political economy. In reality it is not the pursuit of growth that is the issue but growth of what, and to what end. For example, many people would argue that the relentless pursuit of growth in aggregate human wellbeing would be no bad thing (as explored further in Chapter 11). The real problem arises when we obstinately pursue growth using completely the wrong yardstick.

A Grossly Inadequate Measure of Human Progress Gross domestic product (GDP, also referred to as gross national product) is defined as the total value of all goods and services produced in a country in a year—in other words, the total value of a country’s annual output. With the help of many highly competent national statisticians it does a reasonably good job of measuring that: annual economic output. However, it has come to be seen as a measure of far more. For generations of economists and politicians, increasing per capita GDP has been treated not just as the most important measure of a nation’s overall economic progress but also as indistinguishable from increasing national wellbeing. If we accept that one of the key objectives of government is to progressively improve the overall wellbeing of its people (and of their children, and their children’s children), then surely we should be using a measure that is, at the very least, a good proxy for that.

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GDP is not a good proxy for national wellbeing. This is not a new insight. Critics of using GDP as a measure of wellbeing have been around almost as long as GDP itself. For example, in a 1968 presidential campaign speech, Robert Kennedy eloquently eviscerated the GDP as follows: Our Gross National Product . . . counts air pollution and cigarette advertising, and ambulances to clear our highways of carnage. It counts special locks for our doors and the jails for the people who break them. It counts the destruction of the redwood and the loss of our natural wonder in chaotic sprawl. It counts napalm and counts nuclear warheads and armored cars for the police to fight the riots in our cities. . . . Yet the Gross National Product does not allow for the health of our children, the quality of their education or the joy of their play. It does not include the beauty of our poetry or the strength of our marriages, the intelligence of our public debate or the integrity of our public officials. It measures neither our wit nor our courage, neither our wisdom nor our learning, neither our compassion nor our devotion to our country. It measures everything in short, except that which makes life worthwhile.6 Although Kennedy did a good job of calling out some of GDP’s key failings, it is worth analyzing these a little further to inform our search for alternatives. As a measure of human progress and wellbeing GDP is deficient because it • Measures inputs and outputs rather than outcomes. The most fundamental flaw of GDP as a measure of wellbeing is also the most commonly overlooked: It measures inputs and outputs rather than outcomes, which are what we actually care about. It may sound painfully obvious, but if we want to understand societal wellbeing, then the ideal thing we would choose to measure is societal wellbeing (see Chapter 11 for more on this). The next best option would be to measure the things that are most closely associated with wellbeing—known and reliable indicators of wellbeing— and use these (with caution) as proxies. • Ignores nontraded goods, services, and harms. GDP is calculated by adding up the value of goods and services based on their market prices. But this misses out many important goods and services that aren’t traded. For example, if a new dad decides to take some time out of work to bring up his children, this childcare is completely absent from GDP. If instead he opts to keep working and pay someone else to look after his kids—hey presto, GDP rises. In this way, all unpaid domestic labor is excluded from GDP, despite its obvious value. But the exclusions don’t stop at domestic labor. Any time spent volunteering is also absent from GDP. Leisure shows up in GDP only when we spend money on it. And worse still, leisure time itself may be in direct competition with GDP, because the more time we spend at leisure, the less time we have to dedicate to generating GDP. The final class of omissions in the nontraded category

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are externalities—the unintended and uncompensated consequences of economic activities described above—which can be both positive and negative. The omission of externalities means that GDP overstates the benefit of activities that cause negative externalities and understates the benefit of activities that cause positive externalities. • Treats defensive and remediation costs as benefits. Many of the expenditures that add up to GDP aren’t actually about improving quality of life; rather, they aim to avoid reducing it or attempt to undo harm already done. As Robert Kennedy noted, examples include expenditures on security systems, health insurance, policing, and national defense, as well as the costs of dealing with crime, addiction, and preventable health conditions. • Discourages product durability, recycling, and reuse. A finished product appears in GDP figures only once, when it is first purchased. From that point forward, only the additional items that must be bought to keep the initial product working (e.g., fuel, electricity, cleaning products, or spare parts), show up in GDP. To explain why this matters to planetary health, consider the example of a baby stroller. When it’s purchased by family 1 the purchase boosts GDP, but when they sell it on to family 2 (who get just as much benefit from using it), there’s no effect on GDP. The same goes for family 3, family 4, and so on. Had family 1 bought a low-quality stroller, or simply thrown it away when they were done with it, then another two or three new strollers might have been manufactured and sold. This would have been great news for GDP but less good for the planet. Now let’s say family 4 decide the stroller is no longer usable, and they opt responsibly to send it away for disassembly and recycling. The parts and materials that can be reused to make a new stroller make no contribution to GDP when the new stroller is sold, whereas any new virgin raw materials do. As a result, given the choice between two products of the same price, a focus on maximizing GDP growth would lead us to select the lowerquality, shorter-lived, less reusable and less recyclable product every time—despite the fact that this would be worse for the consumer and worse for the planet. • Ignores depreciation and depletion of capital stocks. The gross in gross domestic product refers to the fact that it does not take account of annual depreciation on the capital assets that are used to produce that year’s domestic product. Understanding the rate of deterioration in conventional capital assets such as buildings, machinery, and vehicles can be important to understanding the sustainability of GDP growth. The further problem that GDP counts annual sales of a country’s natural resources, such as mineral deposits or fossil fuel reserves, but ignores the corresponding reduction in the stocks of these resources is also fairly well known but generally ignored when GDP figures are reported. A more challenging omission from GDP is changes in more complex natural, social, human, and intellectual capital assets, which have not generally attracted much attention from national statisticians (these wider “capitals” are discussed further below).

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• Allows the harms of domestic consumption to be exported. GDP values only goods and services produced within a country or region. This means that the value of imports is excluded from GDP, and the value of exports is included. This creates two further problems with GDP as a measure of wellbeing: First, it misallocates the value from consumption of imports to the exporting country; second, it allows the importing country to export the negative externalities associated with production. Neither of these problems would be all that significant if international trade were balanced in terms of the value and environmental intensity of production. However, in many cases trade is skewed in favor of richer countries on both counts. Richer countries tend to produce and export higher-value-added goods and services with lower negative environmental impacts in production (e.g., software and financial services). By contrast, poorer countries tend to specialize in low-value-added production with significant negative impacts (including agriculture and basic materials), which are then imported by richer countries. • Is blind to inequality. This is really an extension of the first point—that GDP measures inputs and outputs rather than outcomes—but it is so significant it merits calling out. GDP and per capita GDP tell us absolutely nothing about the distribution of income and expenditure within a country. Consider two hypothetical communities, each with 100 citizens. In the first country, each person receives and spends $10 each year; in the second, one lucky person receives and spends $901 each year, while the remaining 99 people each have to get by on $1. From the perspective of GDP, the two communities are equivalent: GDP is $1,000 and per capita GDP is $10. The same is true for GDP growth: A country may be achieving impressive annual growth in GDP, but this tells us nothing about who within the country is benefiting from that growth. Although economists may well debate the relative importance of the above issues, few would dispute that GDP can be a decidedly misleading measure of national wellbeing. But if the shortcomings of GDP are so widely known, why is it still by far the preeminent measure of national success? First, GDP does have some significant merits as a measure of economic activity: • Simplicity. It is simple to calculate and very simple to interpret (bigger is better). • Universality. No matter what the nature of an economy, the monetary value of its products and services can be summed to provide a universally recognized measure, which can then also be used as a basis for comparisons between countries. • Objectivity. Because it is based on observable market prices. As a result, GDP enables policymakers and central banks to judge whether an economy is contracting or expanding, which should help them to determine whether it needs a boost or would benefit from some restraint. Beyond the headline number, the national

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income accounts (which form the basis for GDP measurement) allow policymakers, economists, and businesses to analyze the impact of monetary and fiscal policies and other economic shocks on the overall economy and on specific elements of it. It’s easy to see how these merits led to the GDP rising quickly to prominence and staying there. Its simplicity of interpretation appealed to policymakers who were forever grappling with complexity, and to analysts and commentators too. Its relative simplicity to calculate meant that once measurement processes had been established in a few countries, they could easily spread to others. Once enough countries had adopted GDP, a form of network effect took hold whereby any country without credible national income accounts was identifying itself as an economic backwater. This universality also became a formidable barrier to entry for alternative, more sophisticated measures of progress, because creating such measures for all countries and all time periods for which GDP was available would immediately be a significant endeavor. Unfortunately, none of its merits or the reasons for its rise and subsequent endurance make GDP a good measure of societal wellbeing. Simplicity isn’t an advantage if the result isn’t meaningful. Universality isn’t an advantage when all it facilitates is comparisons based on the wrong metric. Objectivity in measuring the wrong thing is hardly a positive either. The problem with our overreliance on GDP is not simply that it doesn’t adequately reflect wellbeing at a point in time but that it actively drives policy and resource allocation in ways that can be detrimental to societal wellbeing and planetary health over time. In short, although with certain caveats GDP is a decent measure of economic activity, to measure societal progress, overall wellbeing, and planetary health, we can and must do better.

Better Measures of Success for Planetary Health Alternatives to GDP In an effort to mitigate some of the widely acknowledged failures of GDP as a measure of human progress, many enhancements and alternatives have been developed over the years. Although none has achieved the prominence of GDP in the minds of policymakers, business leaders, or the general public, some nonetheless continue to make a significant contribution to our understanding of the evolving state of the world. These fall into one of three categories: • Adjustments to GDP. GDP is the starting point, and monetized environmental or social factors are added or subtracted. Prominent examples in this category include the Genuine Progress Indicator (GPI) and Index of Sustainable Economic Welfare (ISEW), which correct GDP using a series of

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monetized environmental and social factors; Adjusted Net Savings (or genuine savings), which aims to provide a true measure of annual net investment in manufactured, natural, and human capital; and a variety of efforts to calculate “green GDP” that adjust GDP by subtracting monetized estimates of the environmental harm of economic activities and in some cases adding estimates of the value of environmental benefits. • Supplements to GDP. Designed to complement GDP with extra social or environmental information. Prominent examples in this category include the System of Economic Environmental Accounts (SEEA) and SEEA Experimental Ecosystem Accounting (SEEA EEA), which are extensions to the internationally recognized System of National Accounts (SNA); and the Sustainable Development Goals (SDGs). The seventeen SDGs are accompanied by 169 targets and 230 indicators (although they lack a single aggregated measure of progress). • Replacements for GDP. Designed to replace GDP with more direct measures of human wellbeing. The preeminent example in this category has long been the Human Development Index (HDI), which combines simple measures of health, education, and living standards into a single country score between 0 and 1. More recently, the UN University and UN Environment Programme (UNEP) have proposed the more sophisticated Inclusive Wellbeing Index (IWI) as a replacement for both GDP and HDI. The IWI aims to measure the combined stock of manufactured capital, human capital, and natural capital as a proxy for societal wellbeing. Although each of the measures described above provides a better measure of human progress than GDP, all share two important drawbacks. First, all rely largely on proxies (activities, outputs, or intermediate outcomes); none directly measures the outcomes we actually seek as a society. Second, none meaningfully incorporates the physical constraints of living on a finite planet. One further measure, proposed by the New Economics Foundation, is the Happy Planet Index (HPI),7 which does a reasonable job of addressing both of these significant drawbacks while using existing, robust, and readily available data sets. It also provides a single aggregated measure that facilitates international comparisons and could be useful for tracking progress over time. The HPI aggregates data on average life satisfaction, average life expectancy (both adjusted to reflect inequality in these outcomes), and ecological footprint in a single index. In so doing, it aims to measure sustainable wellbeing by comparing how efficiently residents of different countries are using natural resources to

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achieve long and satisfying lives. However, the arbitrary way that the index is generated from these national data points, as well as its reliance on the simplistic national ecological footprint per person measure as its benchmark of sustainability, mean that its practical usefulness to policymakers and other decision makers is rather limited. Kate Raworth’s ingenious doughnut (Figure 15.4) takes a different approach. The outer ring of the doughnut or “ecological ceiling” is formed by the planetary boundaries,8 and the inner ring or “social foundation” is made up of a selection of important

Figure 15.4 The doughnut model of the safe and just operating space for humanity, showing a social foundation with lower limits and an ecological ceiling with upper limits. Source: Kate Raworth (Wikimedia), Creative Commons, license CC BY-SA 4.0

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determinants of human wellbeing. Although the doughnut doesn’t propose a helpful single measure of sustainable progress to replace GDP, it does identify what it refers to as the “safe and just space for humanity”—the space in which we can meet the needs of all, within the means of the planet. In place of targeting ever greater GDP, it suggests we simply target living within the doughnut. One obvious drawback of this nonaggregated multicriterion approach is that it doesn’t offer a means of prioritizing between different parts of the social foundation or the ecological ceiling, or informing the inevitable tradeoffs within each or between the two. Recent research indicates that no country currently meets basic needs for its citizens at a globally sustainable level of resource use.9 In fact, no country currently gets close. In one recent analysis, no country that meets more than six of the eleven social thresholds breaches fewer than five of the seven biophysical boundaries. Conversely, no country that breaches fewer than five boundaries manages to meet more than six social thresholds. These stark findings demonstrate the urgent need for us to identify a fundamentally different development trajectory for the world.9

Why Focusing on Outcomes Really Matters At all levels of decision making, decisions are heavily influenced by the available measures of success. As the old adage goes, “What gets measured gets managed.” Unfortunately, this statement tends to hold true regardless of whether or not the measures chosen bear any relation to the outcomes they purport to represent. Above we saw how this can go wrong at a national level. Benevolent governments want to deliver ongoing improvements in societal wellbeing, but they typically choose to measure and manage GDP. As a result, they often end up promoting all sorts of activities that increase GDP but harm societal wellbeing while neglecting activities that would be great for wellbeing but may be bad for GDP. Issues with performance measurement affect public and private sector actors at all levels, not just nationally. For example, many corporations put far too much emphasis on one narrow measure of success: short-term profit. But profit alone does not reflect the wider consequences of corporate activities, nor does it say anything about the state of the assets needed to produce that profit. In much the same way that governments go astray by overemphasizing GDP growth, a narrow focus on short-term profit within companies tends to incentivize the wrong decisions and behaviors and lead to undesirable outcomes. For far too long, governments have focused too much on delivering short-term GDP growth, and corporations have focused too much on delivering short-term financial profits. Both of these fixations will need to change if we are to deliver against the aspirations of planetary health.

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Defining the Outcomes We Want from Planetary Health, to Help Us Get There If we define the core goal of planetary health as being to maximize human health and wellbeing now and in the future, we can lay this objective out in the form of a descriptive equation as follows: (aggregate healthy life expectancy now + aggregate wellbeing now) + [(aggregate healthy life expectancy + aggregate wellbeing) * all future     periods)] = maximized This overarching definition immediately raises some important questions: Is it complete? How might we measure it? And how would this support better decisions for planetary health? At first glance this may seem incomplete. Surely the ultimate measure of planetary health must include some measure of the health of the planet or at least the state of the environment. In fact, counterintuitive as it may seem, we argue that it is actually important for the intellectual coherence of planetary health that its ultimate measure of success not refer to the state of the environment or the health of the planet. If it did, this would in some cases encourage the pursuit of environmental improvements for their own sake, potentially to the detriment of human health and wellbeing. Nonetheless, it remains critically important to value the environment and to protect and enhance this value. Maximizing human health and wellbeing now and in the future requires that the aggregate amount of health and wellbeing achieved in any future period be at least as high as the aggregate amount experienced by people alive today. In other words, it requires that the level achieved today be (at least) sustainable. Environmental conditions significantly influence health and wellbeing today and will shape the health and wellbeing of future generations. Therefore, to achieve this desired outcome, we must identify and protect (at least) the aspects of the environment that will significantly influence human health and wellbeing in the future. Because the role of the environment in human flourishing is so broad and so fundamental, it would be impossible to deliver this vision of planetary health without simultaneously delivering a planet with healthy natural systems. Indeed, the sharp focus on the wellbeing of future generations in our measure of success almost certainly requires a heightened focus on the state and stability of our natural capital and how it can be protected and enhanced to continue delivering benefits into the future. Inequality is also not specifically referenced in our measure of success; however, reducing inequalities is likely to have a fundamental role in increasing aggregate health and wellbeing. Allowing for one relatively uncontroversial assumption, this is almost a mathematical necessity. The assumption is that measures aimed at increasing health and wellbeing are subject to diminishing marginal returns. This reflects (for example) the fact that paying $100 to someone who only has $20 to her name will have a greater impact on her

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wellbeing than paying the same amount to a multimillionaire. Because the poorest 70% of the world’s population own just 3% of the world’s financial wealth,10 and financial wealth is highly correlated with health and wellbeing, the only way meaningfully to increase aggregate health and wellbeing is to target this 70%. Even modest improvements across this huge swath of the population would add up to a lot. By contrast, even substantial increases for the top 1% would be easily offset by any declines in the wider population. The state of the environment, economic inequality, and aggregate health and wellbeing are even more closely intertwined than the preceding paragraphs suggest. This is because the people whose health and wellbeing are most vulnerable to environmental degradation also tend to be the poorest people on the planet. As a result, there are compelling and selfreinforcing reasons to address both environmental decline and economic inequality if we want to deliver increases in aggregate human health and wellbeing now and in the future. In practice, although it is perfectly possible to measure “aggregate healthy life expectancy now + aggregate wellbeing now,” it is inherently more challenging to predict the health and wellbeing of future generations on the basis of today’s conditions and trends. Doing so in such a way that the predictions are responsive to policy decisions and other significant drivers of change today is beyond our current capabilities. As a result, we will need to rely on other interim indicators of success on the journey to planetary health. Nonetheless, understanding what we would ideally be able to measure should help us identify much better interim indicators. As the story of GDP indicates, in absence of the perfect measure, the perils of choosing the wrong indicators are significant. The economists, ecologists, health professionals, and national statisticians developing the next generation of progress measures for humanity will need to think carefully about how any factors they prioritize have the potential to influence human health and wellbeing, now and in the future.

Harnessing Diverse Economic Ideas for Planetary Health Like many disciplines, economics is not a single set of homogeneous ideas to which all people who call themselves economists subscribe. In fact, economics today is made up of numerous related schools of thought, many of which draw inspiration and insight from entirely noneconomic fields and are in effect multidisciplinary pursuits in their own right. We need to draw on many of these schools of economics, including some of the field’s newest frontiers, to find the tools that support the journey toward planetary health. A selection of the most important economic disciplines is introduced below,a and several of these are analyzed further in the subsequent sections of this chapter. a. The definitions and scopes of subdisciplines of economics vary significantly between institutions and evolve over time. For example, at some universities “natural resource economics” has evolved to encompass many aspects of “ecological economics,” and both may be studied as part of a degree in “environmental economics” at another. Nonetheless, their foundations vary significantly, and as we seek to piece together the new economics of planetary health these differences can be important.

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Positive and Normative Economics Before we get into different schools of economic thought, it is critical that we understand a more basic distinction at the heart of economics. Positive and normative economics are two distinct forms of economics, both of which are present in almost every school, branch, and subdiscipline. • Positive economics is the study of economics based on objective analysis and is generally descriptive. It focuses on cause and effect, behavioral relationships, and facts, and it generates assertions that can be empirically tested. Positive economics is also referred to as “what is” economics. • Normative economics is subjective, based on value judgements and often prescriptive. It is often associated with a political ideology. Normative economics is also sometimes described as “what should be” or “what ought to be” economics. It is critical to appreciate the difference of intent between positive and normative economics. But it is also appropriate to question any social science theory that claims to be purely objective—first, because it is almost impossible for even the best-intentioned social scientist to prevent her own values from seeping into her theory, and second, because few scholars want to present openly ideological theories, when presenting the same theories as evidence-based, objective, and value free can dramatically broaden their appeal. Whether for the first or second reason, a great deal of economic theory that is presented as purely positive can also be seen to be distinctly normative, for example due to the terminology used, the unstated assumptions, or the things that are left out. There is nothing inherently wrong with normative economics; it is often essential for translating positive economic theory into engaging and workable policy ideas. But it is always good to know what flavor of economics you’re dealing with.

Environmental Economics Environmental economics began as a subdiscipline of mainstream economics using welfare economic theory to study the effects of environmental policies. Cost–benefit analysis (CBA) was the cornerstone of this early environmental economics. The methods of environmental economics have advanced radically over recent decades, particularly through the direct integration of environmental science but also aided by improvements in data availability, information technology, and advanced statistical methods. The field has also broadened its scope significantly to encompass all areas of market failure, and in many cases it also extends into the traditional domains of natural resource economics and agricultural economics. Assessing the economic value of the environment remains a major topic within the field, and CBA is still widely used to assess the market and nonmarket effects of alternative environmental policies on such issues as air pollution, water quality, toxic substances, solid waste, and even climate change.

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Natural Resource Economics As the name suggests, natural resource economics focusses on the efficient management of natural resources over time. Historically it was concerned primarily with nonrenewable resources such as coal and metal ores. The defining idea in natural resource economics is Hotelling’s rule,11 which asserts that the real price of an exhaustible resource will rise over time as it becomes scarcer. Hotelling’s rule has been significantly augmented over time, perhaps most importantly by Hartwick’s rule,12 which states that a country currently reliant on exhaustible natural resources can seek to maintain levels of economic welfare into the future by investing all of the excess profits (“resource rents”) of resource exploitation into other forms of capital. In practice, however, the available empirical evidence indicates that although the real prices of basic nonrenewable resources can be highly variable in the short term, they have not tended to increase over the long run.4 This is the result of several interrelated factors including technological advances and substitution with alternative materials in response to sustained price increases. Natural resource economics often extends to deal with more complex resources provided by ecosystems, often referred to as natural capital, where it converges with environmental and ecological economics to produce some of the most important ideas in the new economics of planetary health.

Ecological Economics Like several sub-branches of economics, ecological economics now includes multiple variants. In its original form, ecological economics represented a fundamental repositioning of economics as a subfield of ecology, reflecting the observation that the economy operates within the biosphere. Unlike most other branches of economics, which were started by classically trained economists, many of the pioneers of ecological economics trained first as ecologists and then expanded the scope of their work to consider the impacts of humans and economic activity on ecological systems, and vice versa. This systems view led ecological economists to address some big issues head on, including intergenerational equity, the irreversibility of some environmental changes, the inherent uncertainty of long-term outcomes, substitutability between different forms of capital, and the fundamental challenge of achieving economic development given ecological constraints. Many of the big ideas of ecological economics have since been assimilated by environmental economics, and in return, more open-minded ecological economists increasingly use the methods of environmental economics to value complex ecological stocks and flows as a means of ensuring that ecological priorities are reflected in decision making.

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Health Economics and Wellbeing Economics Health economics is a distinct branch of economics with several significant subdisciplines that bear only limited relation to one another. These include demand for health care; supply of health care; planning, budgeting, and monitoring of healthcare activities; and design and evaluation of healthcare systems. However, most relevant and valuable for planetary health purposes are defining, quantifying, and valuing health and wellbeing and understanding the wider determinants of health (beyond health care), particularly those related to economic inequality and the environment. Below we introduce some helpful health economic measures of health burden and improvement and briefly discuss the emerging field of subjective wellbeing assessment, which is covered in more detail in Chapter 11.

Behavioral Economics Behavioral economics is one of the newest and fastest-growing schools of economics and is widely perceived as one of the most positive recent developments in the field. It challenges some of the key assumptions of mainstream economic theory, including the rationality of individuals and the efficiency of markets. It starts from the premise that the best way to understand the workings of the economy is to understand the way the human mind reacts and adapts to market situations. This orientation reflects the fact that many of its key proponents originally trained as psychologists. The tools and insights of behavioral economics are already being applied to subtly influence consumers to make more environmentally sound choices. Reducing the environmental harms from the average modern lifestyle to sustainable levels will require huge behavioral change, suggesting a major role for behavioral economics.

Development Economics Development economics is broadly concerned with the improvement of economic performance and living conditions in low-income countries. Although the diverse theories of development economics include many important ideas, such as international inequities, global power imbalances, and inclusive growth, that provide valuable insights for the economics of planetary health, the most pertinent lessons are in the way development economics has itself developed. Since its inception, development economics has sought to bring the best ideas from all schools of economics to bear on the massive challenges faced by developing countries. It has not constrained itself to the field of economics either, routinely incorporating local social and political factors in its analysis and recommendations. Through this pluralist and pragmatic approach of harvesting, improving, and applying the best ideas, irrespective of source, it has become one of the most influential

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and diverse schools of economics, producing five Nobel Prize–winning economists along the way and setting an example for a new economics for planetary health. To help bring some structure to our diverse new field, we can group the ways that economics can help us achieve planetary health into three categories: • Conceptualizing the relationship between people and planet. Using economic ideas to understand and interpret, measure, and value all aspects of planetary health • Governance and policy for planetary health. Using economic insights to design the institutions, governance frameworks, and policy measures (to realign incentives) to deliver planetary health • Business solutions for planetary health. Using economic insights to refine or transform existing business models and to develop entirely new business models that deliver planetary health The first of these categories, which encompasses the majority of the theoretical content, is addressed in this chapter. The application of this theory in governance, policy, and business is the subject of Chapter 16.

Conceptualizing the Relationship between People and Planet Conceptualizing the Environment Before we move on to insights from newer frontiers in economics, we should acknowledge that mainstream (or neoclassical) economics does have a bit more to offer our understanding of economy–environment interactions than the simplistic vision of profit-maximizing firms and GDP-maximizing nations might suggest. The two most valuable concepts for our purposes are both forms of market failure, in which markets don’t achieve an efficient allocation of resources on their own: externalities and public goods. Before we can properly describe those two concepts, we need to briefly cover some foundational economic ideas.

Welfare Economics Welfare economics is based around the central concept that each person has a utility function (or benefit function), which defines how much utility (benefit) he or she experiences based on a range of factors. The amount of utility a person gets from different choices is defined by his or her preferences, and someone who seeks to make choices that deliver as much utility as possible is described as a utility maximizer. Mainstream economics assumes that people’s preferences are rationalb and that all people are utility b. Strictly, that they exhibit transitivity, continuity, and completeness. In practice, most economists would not argue that people actually make rational choices all the time, just that in most contexts and when aggregated across large populations, the assumption of rationality is a reasonable simplification. The assumption of rational preferences does not (as commonly asserted) preclude altruistic behavior, and indeed it can accommodate a very wide array of very different preferences.

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maximizers. One of the key ways for people to increase their utility is by consuming goods and services. The incremental utility a person gets from consuming one additional unit of a good is called the private marginal benefit [PMB]) from that act of consumption. The aggregate of all individuals’ utility is generally referred to as societal welfare,c and the subfield of economics that focuses on evaluating changes in aggregate welfare is known as welfare economics. Perhaps the best-known diagram in all of economics is the one in Figure 15.5, illustrating the intersection of supply and demand in a market for some imaginary good. The demand curved represents the amount the market will buy at a defined set of prices. Each point on the curve is equal to the PMB of consuming an additional unit. It is downward sloping because few people value the good highly enough to buy it at a very high price, but more and more would do so (or would purchase additional units) at successively

Figure 15.5 Typical depiction of supply, demand, and equilibrium in a market.

c. Although utility and welfare are typically associated with positive and normative applications of economics, respectively, for our purposes we can treat the terms as synonymous. d. The relationship between price and demand is referred to as a demand curve but is almost always illustrated (as here) with a straight line. The same is true of the supply curve.

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lower prices. The supply curve represents the amount the market will produce at a defined set of prices. In a competitive market this is equal to the private marginal cost (PMC) of supplying the good. Each point on the curve represents the cost of producing an additional unit based on the prevailing technology and other conditions affecting supply. An equilibrium quantity and price are reached where supply and demand intersect, in this case at price P1 and quantity Q1.

Externalities In the example shown in Figure 15.6, a negative production externality is present. As described above, this means that the costs faced by the producer are not the only costs of production; some additional costs are imposed on third parties. Pollution is a common example where this kind of externality can arise. Producers are subject only to their private costs of production, regardless of the fact that each unit has a negative impact on society, for example as a result of air pollution from a factory. Wherever societal costs or benefits diverge from private costs or benefits, the market will fail to allocate the efficient level of production. To identify the inefficiency of the

Figure 15.6 Supply and demand with a negative production externality.

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market equilibrium output at Q1, we can compare the social marginal cost (SMC) and social marginal benefit (SMB) at that level of output. At Q1 the SMC exceeds the SMB by a considerable margin, such that people who benefit from the production could compensate those who are harmed by the pollution associated with production, and both would be better off. This is true until output falls as far as Q2, at which point no one can be made better off without making someone else worse off, referred to as the social optimum. The shaded area in Figure 15.6 is the cost of the externality in terms of lost societal welfare. If we were to include actual prices and quantities in Figure 15.6, we could calculate this social cost in monetary terms, even though no actual money would be changing hands. This is an example of nonmarket valuation, which is discussed in more detail below. Nonmarket valuation based on welfare economics has much broader applications and remains one of the most powerful economic tools for delivering planetary health.

Public Goods A public good differs from most common goods by being “nonrival”: One person’s consumption of the good does not reduce the amount of the good available to others. A second characteristic of pure public goods is that they are “nonexcludable”: It is not possible to prevent people from using the good if they want to. Commonly cited examples of pure public goods are common languages, national statistics (or more generally free to use information goods), national defense, and free-to-air television. Most relevant for our purposes are “common pool resources” such as fisheries, grazing land (or common land), and forests. Any of these may once have been thought to have the properties of public goods: that anyone could access them (they weren’t owned by anyone in particular, and even if they were it was infeasible to prevent others from accessing them), and that one person’s use didn’t materially affect anyone else’s, because they were thought to be in essentially limitless supply. In practice, we have learned over time that all are in fact “rivalrous.” Although the common pool resources in these three examples will regenerate if a limited amount is harvested (referred to as the sustainable yield), because it can be difficult to control access to them, and all are essentially free to use, they have tended to be overused and many have therefore become severely degraded. This outcome has been referred to as the tragedy of the commons13 and used to justify either extensive government regulation or private ownership. However, some have argued against characterizing the commons as tragic, highlighting longstanding examples of effective collective management of common pool resources that rely on a range of alternative governance arrangements.14 There are also cases in which the move to government regulation or private ownership of former common pool resources has resulted in unfavorable outcomes, sometimes for the resources themselves and often for the groups that previously relied on them.

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Ecological Economics and Ecosystem Services One of the key criticisms of conventional economic theory is the way in which it tends to position the environment as something outside the economy—something from which the economy can take resources, and into which it can deposit waste, without consequence. By contrast, ecological economics depicts the economy operating within the environment and encourages us to think about the environment itself as a complex and interdependent series of systems, known as ecosystems. An ecosystem is made up of living organisms (plants, animals, and bacteria) and nonliving components (air, water, geology, weather, sun) all interacting with one another. The many ways in which ecosystems contribute to human wellbeing (or welfare) are called ecosystem services. The concept of ecosystem services was popularized by the Millennium Ecosystem Assessment (MA)15 which categorized them broadly as • provisioning services (e.g., food, fiber, fuel) • regulating services (e.g., climate regulation, natural hazard regulation) • cultural services (e.g., aesthetic, recreational, educational services) • supporting services (e.g., nutrient cycling, soil formation)e Figure 15.7 from the MA illustrates some of the key linkages between these ecosystem services and the constituents of human wellbeing. Although economists and ecologists sometimes disagree about the distinctions between “final” and “intermediate” ecosystem services, the link that ecosystem services make between the state of ecosystems and human wellbeing represents a major step forward in our understanding of the close ties between ecology and economics.

Natural Capital Lastly, we come to the most recent conceptualization of the environment in (quasi)economic theory as one of the key “capitals” in a “multicapital” approach (Figure 15.8). Multicapital approaches draw heavily on various fields of economics but also on finance and business management theory. The simplest way to explain the multicapital view of the world is to start from the conventional microeconomic view of the firm. In this view,

e. Subsequent typologies often classify these as ecosystem functions rather than services on the basis that they provide benefits to people indirectly via other “final” ecosystem services. There is a rich literature and significant debate about the appropriate classification of ecosystem services as well as proposals by the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) to recharacterize them as part of “Nature’s Contributions to People” (https://www.sciencedirect.com /science/article/pii/S187734351400116X https://www.tandfonline.com/doi/full/10.1080/26395916 .2019.1669713).

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Figure 15.7 Linkages between ecosystem services and human wellbeing. Source: Millennium Ecosystem Assessment. Ecosystems and Human Well-being: Biodiversity Synthesis. Washington, DC: World Resources Institute; 2005. https://www.millenniumassessment.org /documents/document.354.aspx.pdf

a firm uses its capital, usually held in a combination of financial and manufactured (or tangible) assets, to generate a flow of income (revenue) over time. By combining two capitals, financial and manufactured, with labor purchased in return for wages, firms create value for their customers and shareholders. In a multicapital approach, there’s more to it than that. First, the simple description of labor as an input to be purchased in the labor market is replaced by the concept of human capital, encompassing people’s mental and physical health and wellbeing as well as their competencies, capabilities, and experience. Human capital can be enhanced through investment by the state or private firms in health, education, and training, and it may also degrade over time if neglected.

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Figure 15.8 An example of a multicapital framework. Source: Copyright © March 2013 by the International Integrated Reporting Council. All rights reserved. Used with permission of the International Integrated Reporting Council. Permission is granted to make copies of this work to achieve maximum exposure.

Intellectual capital encompasses knowledge-based intangible assets including legally owned intellectual property (e.g., patents, copyrights, licenses) as well as the procedures and protocols that enable a firm to operate and the brand and reputational value it has developed. Social and relationship capital encompasses shared norms, values, and behaviors between a firm and its external stakeholders, as well as the trust and relationships built up with suppliers, business partners, and other stakeholders, and the firm’s social license to operate. Last, but certainly not least, underpinning all of these other capitals is natural capital (the environment), the stocks of environmental assets such as forests, rivers, oceans, soils. and other natural resources that yield a flow of benefits (ecosystem services) over time. Although manufactured, human, intellectual, and social capital assets tend to depreciate in value over time unless they receive ongoing investment, most natural capital is self-sustaining (renewable) as long as it is used appropriately, and in some cases it may even appreciate over time.

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Although this overview of the various capitals started from the perspective of a firm, a multicapital framework is just as relevant from the perspective of government, individuals, or society as a whole. This most recent reconceptualization of the environment as natural capital within a multicapital framework is significant for three principle reasons. First, it repositions the environment as society’s most fundamental asset, one that underpins all other assets. Second, it steers organizations to identify the ways in which they depend on the environment, not just the impacts they have on it. Because inputs from nature are often unpriced, they can be economically invisible to organizations, even in situations in which they are hugely important and valuable. Identifying natural capital dependencies is therefore a critical first step to managing them (and therefore the environment) more effectively. Furthermore, positioning the environment as a critical asset for society makes the benefits of investing to restore or enhance it much more apparent. Third, it takes a systems approach, highlighting both the interconnections and the distinctions between the capitals and the role that all the capitals play in creating value within society. This makes a multicapital framework particularly relevant to planetary health, which explicitly acknowledges the link between the state of the environment and the health and wellbeing of people and implicitly considers the systemic connections between the environment and society more broadly.

Measuring and Valuing the Environment Now that we have surveyed some of the ways in which economics helps us to understand our relationships with the environment, how can economics help us quantify and protect these relationships? More specifically, how can it identify what really matters for delivering planetary health in a world with many competing priorities? This is where economic valuation comes in. In this context, valuation means simply expressing the importance, worth, or usefulness of something to people. Valuation can therefore be qualitative (A is better than B), quantitative (A is 5× better than B), or monetary (A is worth $50, B is worth $10). However, because it enables comparability between any number of market and nonmarket values and is easily understood, monetary valuation tends to be the most useful for informing efforts toward planetary health. Because the anthropocentric view of value in economics is often misrepresented as being narrowly utilitarian, it is helpful to identify the types of value (referred to as the constituents of total economic value) that most economists would recognize.f

f. Chapter 11 describes another type of value, relation value, grounded in the value of relations either between people or between people and nature.

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First, there are use values. These can be organized into three categories. • Direct use value: The value people get from directly using a good or service; generally consumptive or at least rivalrous (e.g., use of food and materials). This is the value most commonly captured in market transactions. • Indirect use value: The indirect benefits people get without needing to consume the resources that provide them (e.g., climate stabilization, water and air purification by ecosystems). • Option value: The value people place on retaining the option to use a good or service in the future. Second, there are nonuse values. These can be divided into two categories. • Altruistic or bequest value: The value people derive from preserving something for the enjoyment of other unconnected people or future generations. • Existence value: The value people place on simply knowing that something continues to exist, even though they may never expect to see or otherwise experience it (e.g., wild tigers, blue whales, the rainforest). In the most comprehensive review of ecosystem valuation studies yet completed,16 direct use values were found to contribute on average only about 15%–30% of the total economic value of ecosystems.

Nonmarket Valuation As the name suggests, nonmarket valuation techniques are used to value things that can’t readily be bought and sold in markets. This includes goods and services that we get for free from the environment such as clean air and water, protection from floods and storms, and opportunities for recreation, as well as any uncompensated harms caused by environmental degradation, such as the respiratory problems caused by excessive air pollution, or the ruining of a favorite scenic spot by a new development. Nonmarket valuation techniques can also be used where the market price of a good is a poor reflection of its true value. This brings us to the important observation that price is very rarely the same as value, and the act of pricing something has very different implications than the act of valuing it. Price is the amount of money expected, required, or given in payment for something in a market. A person may pay $10 for a good, but value the benefits it provides at $50. (Economists refer to this difference between the price paid and the value derived as consumer surplus.) The price paid should therefore reflect the minimum value that the buyer places on the good, whereas its value to the buyer may be almost any amount greater than that. Suppose the good in question were a favorite country walk, or the blackberries

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picked along the way. The lack of a market for country walks or wild blackberries doesn’t mean that these goods have no value, only that they have no price. Similarly, the act of valuing these nonmarket goods doesn’t mean that they are suddenly up for sale; it simply means that we now have a better understanding of what they’re worth. Country walks and blackberries may seem like somewhat trivial examples, but in fact, many things that are critical to healthy ecosystems and therefore to human wellbeing are very poorly represented in markets, if they are represented at all. For example, trees have a market price based on the utility of their timber for construction or furniture, but the price paid for timber completely ignores the value of living trees in intact forest ecosystems for filtering our air and water, stabilizing the land, sequestering carbon, and providing habitats and places for recreation and enjoyment. If replacing the loss of these benefits were factored into the price of timber, it would be considerably more expensive than it is. In the absence of nonmarket valuation, the default assumption is generally that goods and services which aren’t captured in markets have no value at all. There are four categories of nonmarket valuation technique: revealed preference, stated preference, value transfer, and cost-based approaches. These are distinguished by the way in which they produce estimates of the value of nonmarket goods, services, and harms. The first two derive results consistent with welfare economic theory, as does value transfer if the original value is based on one of the first two methods, and appropriate adjustments are made to reflect the new context. Cost-based approaches lack the coherence of an overarching conceptual framework but can nonetheless be helpful for providing quick and intuitive estimates to inform decisions.

Revealed Preference Revealed preference techniques take advantage of the ways in which people reveal the values that they hold for nonmarket goods through market transactions for related goods and services. For example, values can be revealed by analyzing data on the time and cost incurred to visit an ecological site for recreational purposes, known as the travel cost method. Preferences can also be revealed through the prices of assets with different environmental attributes. For example, comparing the prices of houses in proximity to rivers, parks, or attractive views to those of equivalent houses in different settings (controlling for a range of other factors) can reveal the value that homeowner’s place on these attributes, a technique known as hedonic pricing. A third example arises in labor markets, where statistics show that employees expect higher salaries in return for taking on more dangerous jobs. With these techniques economists are seeking to determine people’s willingness to pay (WTP) for a nonmarket good or willingness to accept (WTA) compensation to endure some nonmarket harm (or increased risk of harm) by analyzing what they actually pay or accept for related market goods and services.

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Stated Preference Stated preference techniques ask people to indicate their preferences directly by using various different types of survey instrument. For example, contingent valuation surveys ask respondents their willingness to pay for a particular good, service, or outcome or their willingness to accept compensation for its loss. A related technique known as a choice experiment presents a series of alternative options, each defined by various attributes set at different levels (including price) and asks respondents to select which option (i.e., sets of attributes at different levels) they prefer. These techniques can be especially useful in determining nonuse values.

Value Transfer Value transfer involves transferring value estimates from existing economic valuation studies to new contexts, making statistical adjustments as appropriate, for example, to take account of differences in population density, incomes, or environmental quality. As more and more primary valuation studies are completed and methods for transferring and adjusting estimates from one context to another improve, the potential to use value transfer to produce quick and inexpensive estimates to inform planetary health decisions is growing.

Cost-Based Approaches Lastly, cost-based approaches look at the market tradeoffs or costs avoided of maintaining ecosystems for their goods and services. For example, this may include examining the costs of building a replacement for a degraded ecosystem service (replacement cost), such as filtration of drinking water or shoreline protection from storm damage. These approaches can also involve estimating the cost of damages to existing property or businesses that might be incurred if the existing ecosystem were to be degraded (damage costs avoided). This is necessarily a very brief introduction to nonmarket valuation. A deeper but still highly accessible overview can be found in The Natural Capital Protocol.17 Done well, and with sufficient understanding of its limitations, nonmarket valuation can be an extremely powerful tool in support of better decision making for planetary health.

Economic Valuation and Distributional Equity Anyone who’s traveled internationally will know that the prices of goods and services can vary substantially from place to place. For example, a typical haircut in Paris or London costs considerably more than a remarkably similar one in Hanoi or Addis Ababa. It’s common to make the connection between the lower prices of goods and services in poorer countries and lower costs of basic inputs and labor. It’s also obvious that these low

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wages in turn contribute to low consumer demand, leading to market equilibria at low price points for anything that doesn’t rely on costly imports. However, most of us don’t extend this line of thought to consider nonmarket goods and services, where the same logic applies. When people in developing countries express their preferences for nonmarket goods and services (whether revealing them through market transactions or stating them in response to survey questions), they do so relative to the prices of market goods, and their own incomes. Thus, although a family in the United States and a family in Uganda may both consider it worth spending an extra 1% of their household income to rent an apartment near a scenic lake (in preference to one the same size in a less pleasant location), this would put the value of the scenic location to the American household at $1,000 per year, versus just $50 per year to the household in Uganda. This trend of lower values for goods in poorer countries applies to most environmental goods (and harms), and for much the same reasons it also applies to most other nonmarket goods (and harms), including human health, wellbeing, and life itself. Clearly few (if any) people would consciously chose to value the lives of people in poorer countries differently from those in rich ones, but this is one implication of the choice we make as consumers whenever we purchase goods produced through international supply chains—which is to say, almost every time we purchase anything. For example, in poor countries, employee health and safety standards are almost always laxer than in rich countries. This reflects the lower value placed on health and life in poorer countries and is one of the reasons that producing in poorer countries tends to be so much cheaper than producing in richer ones. In much the same way, economic valuation of nonmarket goods (and harms) is typically based on local incomes and preferences. Therefore, it will tend to value the environment and human health more highly in richer places and at a lower level in poorer ones. Before we leap to criticize the heartlessness of economists, it’s worth noting that this practice is simply shining a light on reality, making explicit what is otherwise implicit. When valuation results are designed to inform decisions at a local level, relative to other near-term practical priorities, this practice of reflecting differences in income and purchasing power is justified. If we did not do so, the values would be meaningless in the local context. However, when nonmarket values are intended for consideration at multiregional (or even global) scales, when they relate to human health, and when they may also be used to inform long-term (even intergenerational) decisions, equity considerations come to the fore. All these conditions may well apply to nonmarket valuation performed in service of planetary health. In such contexts, planetary health economists may well want to use average values of income across the whole area of their analysis or even to apply positive equity weighting to reflect the greater needs of poorer populations.

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Valuing Long-Term Costs and Benefits Many of the costs of degrading, and conversely the benefits of conserving, natural capital arise in future years—in some instances many decades or even centuries hence. This leads to important questions of intergenerational equity: How should we consider the wellbeing of future generations in decisions we take today? Business managers, individuals, and governments discount costs and benefits expected to arise in the future for a range of reasons. When calculating the present value of future flows (costs or benefits), the annual amount by which they reduce the value of future flows is known as the discount rate. For a business, discounting may occur because it fears it could go bust within a few years, so is happy to accept much lower amounts with certainty today and values future receipts at a significant discount. For a stable business the discount rate should reflect the rate at which it can obtain capital (debt and equity), because this is the minimum return it needs to achieve if it is to generate any additional value. Individuals may discount simply because they want the enjoyment of the goods they can buy today in preference to waiting, even if they could buy more goods if they were to wait a year or two. This tendency to value near-term benefits more than future benefits is referred to as time preference and is the main driver of private discount rates. Social discount rates (of the kind typically used to inform long-term government decisions) are more complex. They must incorporate the ethical aspects of a difficult choice: consumption now or later, for society rather than for an individual. More complex still, they must also consider benefits or costs accruing to future generations. As Table 15.2 shows, the implications of our choice of discount rate are far from trivial. Choosing a discount rate of 5% suggests that we value a benefit accruing to our own grandchildren (50 years hence) at less than one tenth of the utility we would derive from it today, a tricky ethical standpoint to defend.

Table 15.2. The Effect of Discounting in Multiyear Valuation Cash Amount to Be Received in 50 Years’ Time (Excluding Nominal Inflation)

Annual Discount Rate

Present Value of Future Cash Flow

$1,000,000

10%

$8,519

$1,000,000

5%

$87,204

$1,000,000

3%

$228,107

$1,000,000

2%

$371,528

$1,000,000

1%

$608,039

$1,000,000

0.10%

$951,253

$1,000,000

0%

$1,000,000

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In attempting to compute appropriate social discount rates, economists usually separate what they call “pure time preference” from the other major justification for discounting future benefits: that we expect to be wealthier in the future, at least on a societal level. This is based on the simple premise that the same absolute amount, say $10, is worth more to a poor person than to a rich person. Because we generally expect economies to continue growing and people to continue getting wealthier, discount rates should reflect this and prioritize somewhat more consumption today. By extension, we shouldn’t worry overly about people in the distant future, because they will be so much wealthier than we are. Or at least that’s how the logic goes. Unfortunately, there are a few key reasons to question this rosy (and convenient) logic. First, continuing economic growth is far from assured; growth rates have been declining across the developed world, and attempting to predict economic growth rates decades or even centuries from now is at best highly speculative. Potential economic slowdown under climate change scenarios underlines this point.18 Second, the proceeds of economic growth are not likely to be equally shared. Even if economic growth continues for decades, there could still be many people who are no better off or are even worse off than people are today. Lastly, and critically, there is every chance that growth of financial wealth (capital) may come at the expense of declines in the other capitals, such that people may in fact have less overall wealth in its broader sense. The inherent assumption of discounting based on anticipated growth in financial wealth is either that no other forms of wealth that matter will decline or that financial capital can be easily substituted for other forms of capital without leaving people any worse off. In some cases this will be true, but in many cases it is simply not possible to substitute the loss of natural and social capital with more money and stuff and achieve the same levels of wellbeing. There is no substitute for the potential medical cures that are lost when a coral reef or rainforest is destroyed, there is no substitute for seeing a tiger in the wild, there is no substitute for the bonds of community, friendship, and family. As a result, there may be strong arguments for very low, zero, or even negative discount rates to be applied in some contexts and for some decisions. For example, they could be applied in valuations of critical natural capital assets—assets that are fundamental to the wellbeing of current and future generations that could not be substituted or replaced. However, it’s important to remember, before we make the case for zero discounting across the board, that intergenerational equity is not the only dimension of equity we must consider. Distributional equity within and between countries is also a major issue, and we must be conscious of the implications of low or negative discount rates for the most disadvantaged people alive today. At an individual level, the poorest in society—those who live hand to mouth day by day—generally express the highest discount rates of all. After all, what value would you put on the offer of a bowl of rice in 2 months if you don’t have enough food to feed your family today? Adopting very low discount rates across the

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board, in effect prioritizing future consumption, could exacerbate poverty experienced today. The pressing need to address the extreme poverty present in the world today is in effect an equity argument for high discount rates.

Measuring and Valuing Health and Wellbeing Measuring and Valuing Health The most widely used measures of the state of human health are clinically diagnosed conditions (e.g., asthma, heart disease, bowel cancer, diabetes, depression). Condition descriptions and their accompanying symptoms are extremely useful for understanding disease at an individual level and for expressing incidence or prevalence at population level. However, they are less useful when we want to consider the level of health burden, deterioration, or improvement at a more systemic level. For example, is a population with 100 asthma sufferers and 50 diabetes sufferers better or worse off than an equivalent population with 50 asthma sufferers and 100 diabetes sufferers? Based on the conditions alone we can’t tell; we need a set of common units that enable us to aggregate and compare different diseases. This is where disability-adjusted life years (DALYs) and qualityadjusted life years (QALYs) come in. DALYs combine mortality and morbidity effects into a single comparable unit of health burden.19 A DALY of 1.0 indicates a year of death, and a DALY of 0.0 indicates a year of perfect health. Indicative annual “DALY weights” have been estimated for hundreds of different conditions (Figure 15.9). The magnitude of an annual DALY weight can be interpreted as the extent to which a given condition reduces the sufferer’s quality of life on a scale from 0.0 to 1.0. Mild or brief conditions have low annual DALY weights, whereas severe and lengthy (or chronic) conditions have high DALY weights. By combining the duration of disease multiplied by the DALY weight (referred to as the years lived with disability [YLD]) with the years of life lost (YLL) due to premature death (if applicable), we can estimate the number of DALYs caused by any given condition at any age of onset. A QALY is effectively the inverse of a DALY, so a QALY of 1.0 indicates a year of perfect health.g DALYs and QALYs are extremely useful units of measurement because they enable comparability across many hundreds of different health states for any population. DALYs and QALYs can also be used to express the change in health outcomes (observed or predicted) as a result of any given activity. As a result, they are increasingly used to g. QALYs and (avoided) DALYs share many attributes, but they have historically been calculated in different ways and used for somewhat different purposes. DALYs are best known as the key measurement unit in the Global Burden of Disease (http://ghdx.healthdata.org/gbd-2017) and are most commonly used to express the health burden associated with conditions or risk factors for conditions. By contrast, QALYs are most often used to express the benefits of particular forms of treatment or prevention.

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Figure 15.9 Sample DALY calculations for asthma and ischemic heart disease.

evaluate (or predict) the effectiveness of decisions intended to have significant impacts on health. Logically this should extend to any measures aimed at delivering planetary health. A healthy life year (HLY) is the plain English equivalent of a QALY or an “avoided DALY.” Healthy life expectancy (HALE) is the equivalent number of years in perfect health that a newborn can expect to enjoy, after any YLDs are subtracted. Overall, global HALE at birth in 2015 for males and females combined was 63.1 years, 8.3 years lower than total life expectancy at birth. In other words, poor health accounted for a loss of nearly 8 years of healthy life on average globally.20

Measuring and Valuing Wellbeing Some definitions of health encompass all of wellbeing, and it is generally accepted that wellbeing is a core component of health and vice versa. Although there is some debate around definitions and nomenclature, what matters most for measurement and valuation is recognition that there is more to human flourishing than can be captured in clinical measures of physical and mental health (as summarized through DALYs and QALYs), and this “more” is hugely important to people’s overall experience of life. For the purposes of

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valuing health and wellbeing using economic methods, it is therefore generally preferable to treat them as distinct (if often overlapping) outcomes. This approach reflects the fact that a person’s sense of wellbeing can increase even as their clinically defined physical or mental health declines (e.g., because friends and family are nearby) and equally that many changes in life circumstances (e.g., getting a job, getting married) can improve a person’s wellbeing without showing up as a change in clinical health. As described in Chapter 11, approaches for estimating and valuing changes in subjective wellbeing are advancing rapidly, to the extent that several governments now recommend such methods as part of their guidance on policy appraisal (e.g., see for HM Treasury, 201821). Using methods similar to those described above for valuing other nonmarket goods, it is possible to arrive at monetary valuation estimates for health and wellbeing outcomes as well. This can be achieved through surveys (stated preference) that ask people how much they would be willing to pay to avoid a given health outcome, or reduction in wellbeing, or conversely how much they would be willing to accept in compensation for enduring that outcome. For example, the United Kingdom government’s estimate of the monetary value of a healthy life year is GBP £60,000.21 By expressing the value of (non–health-related) wellbeing outcomes in monetary terms as well, we can combine these different outcomes and understand their relative importance in a common currency. We can also sum them across the population and estimate them for future generations based on trends evident today. Valued health and wellbeing outcomes therefore provide us with the measurement units we need to evaluate progress toward planetary health—aggregate human health and wellbeing, now and in the future.

Conclusions Two centuries of global economic growth have radically improved living standards for most people, lifted billions out of poverty, and enabled investments in public health and research that have transformed health outcomes around the world. At the same time, as many chapters of this book have made clear, the threats to planetary health posed by the sheer scale and impact of the modern economy are grave, and the challenge of overcoming them is significant and pressing. Although we should not overstate the role of economics as a discipline in bringing us to this dangerous point in human history, economic dogma, manifested particularly through an unrelenting focus on GDP growth among policymakers, has undoubtedly played its part. Nonetheless, the tools of economic theory, combined with novel insights from established and emerging transdisciplinary branches of economics, also offer the greatest hope for devising practical and self-reinforcing solutions to planetary health challenges. New

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theories that highlight the roles of natural, social, and human capital will be central to this, as will the methods of nonmarket valuation developed in environmental economics, the practical tools of health economics, the big reframing ideas of ecological economics, and the insights into human motivations offered by the exciting field of behavioral economics. In our efforts to harness the potential of economics for planetary health, we can draw on the example set by development economics, which unashamedly takes on board, combines, and improves on the best ideas from many schools of economics, and is at its best when it is pragmatically adapted to help address specific challenges. If we are successful, then our new economics of planetary health will help us to devise better models for governing global and local commons and to develop new business models that are in harmony with planetary systems. These two hugely important applied topics are the subject of the next chapter.

Authors Will Evison is a sustainability economist based in the United Kingdom. He works collaboratively with companies, governments, and nongovernment organizations around the world to help them solve important sustainability problems. Will was a leading author of the Natural Capital Protocol, an editor and author of The Economics of Ecosystems and Biodiversity (TEEB) report for Business and Enterprise, and has been a longstanding advisor to the World Business Council for Sustainable Development, the World Economic Forum, and the Natural Capital Coalition. Sam Bickersteth was executive director of the Rockefeller Foundation Economic Council on Planetary Health at the Oxford Martin School, 2018–2019. He was previously chief executive of the Climate and Development Knowledge Network, supporting climate research and policy for developing countries, and has worked for the University of Oxford, PwC, DFID, and Oxfam. He has 30 years of experience living and working in developing countries across Africa, Asia, and Latin America.

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O’Neill DW, Fanning AL, Lamb WF, Steinberger JK. A good life for all within planetary boundaries. Nat Sustain. 2018;1(2):88–95.

10. Credit Suisse. Global Wealth Databook 2018. 2018. https://www.credit-suisse.com /about-us/en/reports-research/global-wealth-report.html. 11.

Hotelling H. The economics of exhaustible resources. J Political Econ. 1931;39(2):137–175.

12. Hartwick JM. Intergenerational equity and the investing of rents from exhaustible resources. Am Econ Rev. 1977;67(5):972–974. 13. Hardin G. The tragedy of the commons. Science. 1968;162(3859):1243–1248. 14.

Ostrom E. Governing the Commons: The Evolution of Institutions for Collective Action. Cambridge, UK: Cambridge University Press; 1990.

15.

Millennium Ecosystem Assessment. Ecosystems and Human Well-being: General Synthesis. Washington, DC: Island Press; 2005.

16.

de Groot RS, Wilson MA, Boumans RMJ. A typology for the classification, description and valuation of ecosystem functions, goods and services. Ecol Econ. 2002;41(3):393–408.

17. Natural Capital Coalition. Natural Capital Protocol. 2016. www.naturalcapitalcoalition. org/protocol. 18. Kahn ME, Mohaddes K, Ng RNC, Pesaran MH, Raissi M, Yang J-C. Long-Term Macroeconomic Effects of Climate Change: A Cross-Country Analysis. Cambridge, UK: University of Cambridge Faculty of Economics; 2019. http://www.econ.cam.ac.uk/research-files /repec/cam/pdf/cwpe1965.pdf. 19.

Murray CJ. Quantifying the burden of disease: the technical basis for disability-adjusted life years. Bull World Health Organ. 1994;72(3):429–445.

20. WHO. Healthy life expectancy (HALE) at birth. In: Global Health Observatory (GHO) Data. n.d.. https://www.who.int/gho/mortality_burden_disease/life_tables/hale_text /en/. 21. HM Treasury. The Green Book: Central Government Guidance on Appraisal and Evaluation. London, UK: HM Treasury; 2018.

16 The Business of Planetary Health: From Economic Theory to Policy and Practice Will Evison and Sam Bickersteth

Using Better Economics to Achieve Better Outcomes Chapter 15 started by exploring the economic history behind our current state of planetary ill health. It then went on to summarize the most promising areas of economic theory for use in our effort to deliver on the vision of planetary health. This chapter seeks to apply the theory from Chapter 15 in two key areas. First it explores how governance and policy must evolve if we are to deliver on planetary health. Next, it turns to how the creativity, dynamism, and vast resources of the private sector can be harnessed to the same end. In both cases, it draws heavily on the theory presented in Chapter 15 to explain the challenges and opportunities that lie ahead.

Governance and Policy for Planetary Health The Need for Governance of Planetary Health The global environment spans multiple jurisdictions and is often referred to as a global public good. As introduced in Chapter 15, in economic terms it is more accurately characterized as a global common pool resource, because although it is difficult to restrict its use (it is often “nonexcludable”), one person’s use of it can, and often does, have an impact on other users (its use is often “rivalrous”). These characteristics are at the heart of many

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threats to planetary health. Planetary health is not simply a local level issue but concerns the management of pollution, overfishing, biodiversity loss and, other “bads” that span national boundaries. Thus, the focus of planetary health on large scale, transboundary environmental stressors such as climate change or ozone depletion, and their impact on human wellbeing demands coordination and cooperation between states. Consequently, multilateral governance is an essential element of implementing a planetary health agenda alongside economics and associated policy tools. Together with the spatial dimension of planetary health, there is a challenging temporal dimension. For example, not only might my present carbon emissions or consumption of finite common resources such as ocean fish stocks negatively affect someone besides myself, it may do so at a later time, even generations later, because of the cumulative effect of this behavior. Garrett Hardin’s work on the tragedy of the commons set out the consequences of a noncooperative approach to the management (or more often mismanagement) of common pool resources.1 Elinor Ostrom refuted the characterization of the commons as tragic and questioned the standard policy responses of privatization or state control.2 Based on her studies of well-managed commons, she identified institutional design principles that could help avoid mismanagement; she won the 2009 Nobel Prize in Economics for her “analysis of economic governance, especially the commons.” Effective institutions, at both national and international levels, are necessary to help address both the transboundary and intertemporal problems of planetary health. Shortterm political cycles can work against the need for long-term planetary health solutions, so international regimes, though slow and painful to construct, can have greater durability than purely national legislation. Health problems, like those of the environment, often span jurisdictions and require some sort of coordination by countries to address them. Although this can make international health and environmental issues appear similar, there are often clearer, shorterterm benefits to solving health issues. For example, most governments appreciate the value of working together to address risks of infectious diseases or pandemics; these can bring specific short-term gains. However, the connections between longer-term environmental change and changes in human health have been poorly understood, and therefore incentives for improved governance and decision making have been less apparent. International regimes, whether in health, environment, or trade, exist because of their global public good characteristics and the perceived benefits they can bring. However, when agreeing to work together, countries have to forfeit part of their own ability to make sovereign decisions—generally a politically difficult undertaking. This section highlights what can be done to improve institutional and governance arrangements as the demand for cooperation on planetary health grows.

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Theoretical and Practical Issues of Governance Economic theory on cooperation and coordination faces the “free rider” problem: Although countries, groups, or individuals may be better off collectively if they cooperate in managing a shared resource, an individual country or group may be even better off (at least for a while) by opting out and benefiting as a free rider from the cooperative behavior of others. Coordination is easier (as in the case of eradication of smallpox) than explicit cooperative agreements when countries may be required to take reciprocal actions that they otherwise wouldn’t. One way to avoid free riding and enforce cooperative agreements is trade restrictions. The threat of harm from sanctions on nonsignatories may be effective at deterring free riding. The alternative to a negative “stick” type incentive are positive “carrot” type incentives, which can include access to financial mechanisms or technologies. Many international agreements foster global participation in this way, in particular as an incentive for developing countries; the Green Climate Fund and Clean Development Mechanism are two such finance tools used to foster cooperation in climate change agreements. All multilateral agreements sit within the wider sphere of international relations, and their progress can be determined by wider diplomacy and geopolitics. Furthermore, many attempts at creating incentives for global environmental cooperation have been fraught with complexity when the largest countries’ positions have not been aligned or when their domestic political constituencies do not support the approach. This was the experience at certain times in the history of the United Nations Framework Convention on Climate Change (UNFCCC), notably at its failed meeting in Copenhagen in 2009. One notably successful international environmental agreement is the Montreal Protocol on Substances That Deplete the Ozone Layer. A strong alignment of interests within a limited group of producer and consumer countries, domestic political commitment, readily available technical alternatives, and a specific focus are some of the reasons for its success.3,4 A number of successful regional agreements have addressed transboundary pollution, such as the Convention on Long-Range Transboundary Air Pollution, which tackled the impacts of acid rain. Ideally, all countries would come together to agree on measures to protect planetary health. In practice, this may not be workable, particularly in view of the tight timeframes for action, set against institutional and political inertia. One way around this is the formation of coalitions, or clubs of willing participants. The emergence of subgroups of countries establishing common rules to confront climate change has become significant in leading action, opening up space for new technologies, competitiveness (and learning), and creating diplomatic leverage on nonparticipants. Clubs, such as a climate club for countries following a common carbon price, could use overt trade measures against nonparticipants; others might emphasize the potential internal benefits rather than relying

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on external penalties. This exemplifies a more plurilateral approach as opposed to a comprehensive, inclusive multilateral type agreement. Strong political leadership is an essential requirement for action on planetary health. In government, this may need to come from the head of state because it involves multiple sectors, long-term vision, and a strong narrative. Action on climate change has shown that leadership from a single sector such as by the environment or health ministry may be insufficient until leadership emerges from the minister of finance, minister of planning, or president, who are best placed to address the national interdependencies of planetary health. Additionally, leaders need to establish a compelling narrative to build domestic support across a wide range of stakeholders including parliamentarians, business, media, and civil society. Policies that advance planetary health are likely to be disruptive and generate losers as well as winners across sectors, geographies, genders, and generations, underscoring the importance of laying out their benefits in terms of health, environment, growth and jobs, and mechanisms to compensate losers and manage tradeoffs. Climate change agreements have been undermined by the absence of consensus on the causes of climate change and the uncertainties and timeframe regarding impact. When policymakers engage with the more immediate requirement of human health and wellbeing, planetary health provides a stronger political narrative. In an era of globalized trade, planetary health measures have to take account of the flow of goods, their impacts on both producing and consuming nations, and any incentives and barriers. International trade rules, as well as dissemination of technology and intellectual property, have a bearing on other multilateral agreements; accordingly, the World Trade Organization is relevant to any international climate or planetary health agreements. In addition, border adjustments (normally taxes or tariffs) may be used to incentivize trade in cleaner, nonpolluting goods on both a bilateral basis or in multilateral groupings. In summary, there are incentives and enforcement mechanisms that can enable effective international planetary health governance. Some of these are “hard” approaches such as imposition of trade sanctions on noncooperating countries. Others are “soft,” voluntary incentive-based approaches facilitated by access to finance and technology; this is the approach taken with the Intended Nationally Determined Contributions in the Paris Agreement.

The Current Institutional and Governance Context The United Nations, a central component of the Bretton Woods system of multilateral government established after World War II, remains key to global governance across a variety of areas including health, environment, and climate change. Since 1992 the UNFCCC has endured as a process to “avoid dangerous anthropogenic interference” with

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the climate system. It provided the framework for the quantified agreement made in Paris in 2015. Other international processes that emerged from the first global sustainability conference, the 1992 Rio Convention, included agreements on desertification and biodiversity as well as Agenda 21. Despite recent progress with the Convention on Biological Diversity (CBD) and its Aichi Targets, these have fared less well. However, these earlier international processes played a role in leading to the overarching global agreement on Sustainable Development Goals (SDGs) in 2015 (Figure 16.1). This remains a remarkable moment of global agreement by all countries, providing a kind of global business plan for planetary health with its seventeen high-level goals and 169 targets for the future health of our planet and the people on it. Planetary health responsibilities within the United Nations are spread across a number of organizations including the World Health Organization (WHO), the UN Environment Programme, the UN Development Programme, the Food and Agriculture Organization, and UN Habitat, and a number of conventions including the CBD and the UNFCCC. These institutions and convention processes have tended to be siloed, focusing on outcomes related to their specific mandate and missing opportunities to achieve synergies with planetary health outcomes. For example, only in 2018 was the first Air Pollution and Health Conference convened by the WHO, highlighting the evidence and solutions to the interconnections of health, climate change, and air pollution. Global governance has been increasingly bedeviled by polarity, complexity, and fragmentation. In response there has been a broadening of new actors tackling global environmental and other issues. For some years, civil society organizations have worked

Figure 16.1 The Sustainable Development Goals.

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alongside government negotiators in international processes (such as climate or SDG negotiations), but business groups and subnational actors, especially cities, have become active more recently. Coalitions of city mayors coordinated by groups such as C40 and international businesses coordinated by organizations such as the World Business Council for Sustainable Development have brought the voice of these groups into international governance while accelerating action by the groups themselves. Some groups such as the Natural Capital Coalition and the Non-Communicable Disease Alliance have specific objectives; others, such as the Under 2 Coalition (subnational actors seeking to support the Paris Agreement), bring in new players such as regional and provincial governments. This polycentric approach to shifting norms, behavior, and rules has become increasingly common and extends from institutions to citizens given the capacity of social media to engage. Civil society movements using social media such as Avaaz (a global online campaigning organization with 55 million members) have demonstrated the power of such approaches to mobilize public opinion and influence change over short periods of time.

Economic Policy Instruments for Planetary Health There is a wide array of policy tools to manage planetary health. These can be classified into two general categories as either price/market-based, or nonprice regulatory instruments. Taxes and subsidies are straightforward economic measures designed to internalize externalities and are widely used in planetary health. Although a global carbon tax has been hard to implement, it remains, in theory, one of the most effective levers to address climate change; some fifty carbon pricing schemes are now being implemented, several at substantial regional scale such as the European Union Emissions Trading Scheme.5 Many other planetary health taxes are in place at national level, such as fuel taxes and landfill or waste taxes. Subsidies are similar to taxes but work in the opposite direction as they offer payments for actions that create external benefits; payments for ecosystem services are a prominent example, used by downstream water users to pay upstream land managers to maintain the landscape and thus the quality of water. There are many other forms of subsidy-including incentives to develop new technologies; these are common in the early phase development of renewable energy and other clean technologies. Biodiversity offsetting is another mechanism used to maintain habitats.6 “Hard” incentives come from mandates, standards, regulations, and bans and have been classically used to deal with hazardous chemicals. They can be easier to set up than market-based policies, but implementation depends on institutional capacity both to enforce and to comply. Their acceptability also depends on social and political context and public information. In practice many planetary health issues are addressed through a combination of price and nonprice instruments alongside behavioral changes and nudges. Table 16.1 summarizes some of the key advantages and disadvantages of policy measures commonly used to address planetary health issues.

Table 16-1. Pros and Cons of Different Policy Options for Planetary Health Solution Direct regulation

Description Bans or mandates The regulator sets a fixed limit for pollution or pollution-related activities.

Examples: Mercury emissions in waste water; vehicle emission standards

Taxes and subsidies

The regulator sets a unit tax on pollution or pollution-related activities intended to achieve the socially optimal outcome.

Examples: Carbon tax, fuel tax, sugary drink tax, conservation payments

Advantages · More certainty on desired level of pollution · Doesn’t rely on manipulation of economic incentives · Politically more palatable than price instruments · Adheres to the polluterpays principle · Internalizes the costs of the externality · Greater certainty over cost of compliance · Government revenue · Carbon tax can drive innovation more effectively than targeted (e.g., fuel) taxes. · Subsidies can drive innovation and bring down early-stage costs.

Cap and trade with environmental permits

The regulator issues a fixed amount of pollution permits (Q′ *), which agents can use to cover their pollution. Permits can be traded between polluting agents, so if one agent has an excess of permits, it can sell to another agent who has a shortfall.

Examples: SO2 markets in the United States Auctions used for renewables investments

· If quantity of permits is set at (Q′ *), should lead to optimal level of production with permit price P′ *. · Results in the most cost-effective abatement · If permits are auctioned rather than grandfathered, it internalizes the cost of the externality.

Disadvantages · Limited certainty on cost of compliance · Can impose disproportionately high costs on some market agents · Depending on monitoring and enforcement capabilities · Risk of fraud and corruption · Less certainty over resultant level of pollution · Relies on a detailed understanding of abatement costs to set the tax at the correct level · Distributional or equity impacts and risk of rent seeking by vested interests · Subsidies can be for planetary health bads (e.g., fossil fuels, damaging agricultural practices) as much as goods. · Requires a well-functioning permit market · If permits are grandfathered, then there is no government revenue. · Typically, too many permits are issued, keeping price low. · Permits are insensitive to swings in economic activity.

· Cheap to administer

Feed in tariffs Behavioral nudges

· Public information such as fair trade or ecolabeling · Certification schemes · Ranking of environmental or health performance · Marketing campaigns

· Cheap to run · Work best in conjunction with other measures

· Impacts vary across different sectors of society.

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Business Solutions for Planetary Health What Is a Planetary Health Business? At a conceptual level, it’s easy to explain what a planetary health business looks like: It is a business that contributes to improving human health and wellbeing, now and in the future. But this immediately raises some challenging questions. Even a simple business with a small range of products has many different effects on health and wellbeing. Its products themselves could be good for the health of its customers, but its production practices may still result in pollution, which is bad for the health of people living close to its factories. Should we be concerned only with whether the overall net effect is positive? Or must all effects be positive? Even if the company itself can adapt its production practices to cause zero harm, and it sells products that actively improve health, what about its suppliers? What about the extraction of the resources it relies on? What about the indirect effects of use and disposal of its products? These questions invite us to think about the business model itself—how the business goes about generating revenue and making a profit. This in turn requires us to consider what business analysts refer to as the value chain. A value chain includes the whole series of activities and processes associated with a product or service along its life cycle. For a typical product, these include material extraction and processing, manufacturing, distribution and sale, use, and disposal (or recycling or reuse). At each stage, there may be both positive and negative effects on planetary health. Furthermore, some of these effects will materialize now—such as the wellbeing the customer gets from the product, or the wages enjoyed by the company’s staff—and others may be felt only years or even generations hence, such as the long-term climate warming effects of the greenhouse gases (GHGs) from the energy needed to power the product. In an ideal world, every business model, and indeed every single business decision, would take into account all possible consequences for human health and wellbeing, now and in the future, from all parts of the value chain. Remarkably, new technology and big data approaches, combined with advances in the valuation of natural capital, health, and wellbeing (described in Chapter 15) are enabling some businesses to get close to this ideal (see for example, Case Study 16.1) and to transform their business models in the process. Some are also embracing transparency and communicating publicly about their progress. However, when considering the majority of business models today it is helpful to start with a far simpler rubric. We know from Chapter 15 that achieving the ultimate goal of planetary health—to maximize health and wellbeing now and in the future—will require the following: • Improved stewardship of natural capital, including living within planetary boundaries • Improvements in aggregate human health outcomes (particularly through enhanced health equity)

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• Improvements in aggregate human wellbeing (particularly through enhanced wellbeing equity) Concerning the first of these, although corporate consideration of planetary boundaries is at an early stage, various methods have been proposed to scale down planetary boundaries for use at corporate or value chain scales.7 The most established approaches relate to the climate change boundary and are commonly referred to as science-based targets. For other planetary boundaries, it is first necessary to define regional boundaries before these can be allocated among relevant actors. In all approaches, the general principle is to allocate fair shares to all actors (including businesses) such that the total amount allocated falls within the relevant planetary boundary. There are several potential approaches for allocating fair shares to businesses, but a common approach is to base allocations on revenue, value added, or physical output, at a target intensity per unit of the chosen measure that is compatible with staying within the relevant planetary boundary. Although assessing company-level planetary boundaries for all companies and all boundaries wouldn’t be feasible in the near term, it is typically obvious which one or two boundaries any given business is most at risk of transgressing, making for a much more practical undertaking. With this in mind, the three determinants proposed above (planetary boundaries, human health, and human wellbeing) help us define three categories of business model based on their relationships to planetary health. A business model may be • Currently incompatible with planetary health: A business model is currently incompatible with planetary health if it requires all or part of its value chain to operate outside planetary boundaries in order to be commercially viable. An example of a business model that currently fits this description would be an open-face coal mining company. As well as contributing directly to land system change, freshwater extraction, and climate change, the company’s revenue relies on its customers further down the value chain burning coal to produce energy. There is currently no commercially viable technology that can reduce the GHG emissions from coal-fired generation to levels consistent with planetary boundaries. A business model could operate safely within planetary boundaries but still be incompatible with planetary health if its commercial success relies on harm to human health or wellbeing. For example, a tobacco company may be able to reduce the GHGs, water consumption, and chemical pollution from tobacco cultivation, processing, and distribution to within planetary boundaries. However, if it still relies on the sale of conventional cigarettes—the cause a major health burden around the world—then it is not currently compatible with planetary health.

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• Compatible with planetary health: A business model can be considered compatible with planetary health if it is commercially viable when all parts of its value chain are operating within planetary boundaries and it is not otherwise harmful to human health or wellbeing. Such a business may still cause moderate harm as a result of the use of its fair share of the planetary boundaries, but this can still be consistent with enhancing aggregate human health and wellbeing given the incremental consumption that the company’s activities enable (and with the proviso that this consumption is not itself harmful). It is also important to note that no single business can deliver planetary health alone, and in spite of operating within planetary boundaries, its overall compatibility with planetary health still relies on the actions of many others. This is one reason why effective global and regional governance are also essential prerequisites for planetary health. • Actively beneficial for planetary health: A business model can be considered actively beneficial for planetary health if – It is commercially viable when all parts of its value chain are operating within planetary boundaries, it has a net positive effect on some (or all) planetary boundaries, and it is not otherwise harmful to human health or wellbeing. For example, a business can be GHG net positive if it sequesters more GHGs each year than it emits to the atmosphere. – It is commercially viable when all parts of its value chain are operating within planetary boundaries and it produces outputs that actively enhance human health and wellbeing. So far so good—we have defined broadly how businesses need to operate to achieve planetary health—but this has been based on an entirely outside-in perspective. What actually drives the way businesses operate at present? And what factors will lead new business models to emerge and drive existing ones to transform into positive agents for planetary health?

Business Risks and Opportunities in the Transition to Planetary Health At its core, successful business strategy is about identifying potential risks and opportunities early—minimizing the risks and maximizing the opportunities—in order to protect or create value. The transition to an economy that can sustain planetary health presents two major sources of risk and opportunity for firms, relating to their impacts and dependencies, respectively. • Internalization of externalities: The hitherto externalized costs of business activities can be unexpectedly and perhaps abruptly internalized. Where externalities are negative, this may present a major source of risk. Where externalities are positive, businesses may have the opportunity to capture additional value.

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• Overlooked dependencies: Many businesses have unseen dependencies on functioning ecosystems (natural capital), exposing them to risks where these dependencies are threatened by environmental declines. In other cases, however, new business models that work with nature—embracing and harnessing dependencies—can reduce costs and volatility and therefore increase value. Importantly, this transition to planetary health also presents major opportunities for entirely new business ventures that harness breakthrough ideas and disruptive technologies to solve environmental challenges.8,9 The presence of significant negative externalities caused by existing business models helps to highlight where these transformative opportunities may arise.

The Age of Internalization In the last two decades, the context for business has changed almost beyond recognition. New technologies are rapidly increasing people’s awareness of the external costs and benefits of business, as well as providing them with new channels to interact, share information, and make their feelings known. At the same time, technological advances are enabling new forms of regulation and new means of monitoring and enforcement at levels that simply weren’t possible only a decade ago. The potential for the hitherto externalized costs of business activities to be unexpectedly and abruptly internalized is a major and increasing source of business risk. Four of the key pathways through which negative externalities can be internalized are as follows: • Regulation and legal action: Regulation can be imposed requiring firms to improve pay or conditions for their employees, restricting their access to ecosystem services, or raising the cost of doing so. Examples include minimum wage and healthcare legislation, restrictions on use or outright bans (e.g., conservation areas, fishing quotas, CFC phaseout), establishment of tradable permit markets (e.g., SO2 and CO2), and imposition of taxes (e.g., packaging taxes). Fines and compensation settlements from legal action against unethical practices or environmental incidents can be significant. • Changing operating environment: Rapid urbanization, pressure on infrastructure, changing market and social structures, and heightened community expectations can make setting up new operations trickier and force changes to existing business models to retain competitiveness or a license to operate. Environmental degradation, resource scarcity, and increasing frequency of extreme events disrupt operations, imposing some of the costs of environmental decline directly onto company balance sheets and income statements.

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• Stakeholder actions, relationships, and consumer preferences: Stakeholders may take specific action in an effort to change a company’s social or environmental practices (e.g., high-profile nongovernment organization [NGO] campaigns). Alternatively, a company’s poor approach to social and environmental factors may, over time, detract from the quality of its relationships with key stakeholders such as customers, suppliers, and employees, leading to reduced revenue, increased costs, and lower productivity. • Voluntary action: Companies may undertake voluntary action to reduce their externalities. This may be in response to stakeholder pressure, as part of their competitive positioning, to seize market opportunities, to save money, or simply to manage potential risk. This may entail upfront costs such as capital expenditures but often leads to cost savings or other benefits for the business, including enhanced reputation or better relationships with stakeholders. The trend toward greater internalization of externalities is well understood, and at a societal level it appears to be just that: a trend, gradual and largely predictable. However, at the level of a sector or firm in a given market, it can be anything but. For example, in 2004 stakeholder concerns about its proximity to protected natural areas resulted in the refusal of planning permission for a major new port at Dibden Bay near Southampton in the United Kingdom. The share price of the port’s developer dropped by 11% in the following days, and it was forced to write off £45 million in sunk costs.10,11 In another example, in 2005 the state government of Kerala, India suspended the permit of a major bottling plant because of concerns over the plant’s impact on local freshwater levels and quality.12 The unpredictable nature of internalization events makes the risks posed by outstanding externalities difficult to manage and favors early understanding and proactive steps to reduce negative externalities wherever possible. Figure 16.2 illustrates the impact on business costs of occasional but abrupt internalization of externalities over time. Only the last pathway identified above—voluntary action by firms—is truly manageable and predictable.

Capturing Positive Externalities However, externalities are not limited to costs; businesses also generate a range of positive externalities. For example, they stimulate employment, which benefits local economies and communities; they provide health care and training for staff, which increases their employability and usefulness to others; and many also steward land that provides important public ecosystem services. In some cases, these positive externalities present direct opportunities for firms to capture incremental revenue. For example, increasingly successful certification programs are allowing producers to internalize some positive production externalities, whether directly by attracting a price

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Figure 16.2 Illustrative profile of societal costs and private costs over time. Each arrow represents a stepwise transfer of externalized costs to a private firm. Such transfers can be abrupt and can result in considerable increases in operating costs.

premium or indirectly through access to retailers who are increasingly committing to sustainable sourcing. The estimated retail value of certified sustainable seafood reached US$11.5 billion in 2015.13 Another prominent route to value creation through positive externalities is via corporate brand and reputation. Although examples of reputational risks may dominate the headlines, credible evidence of positive social and environmental impacts can strengthen customer loyalty, improve employee engagement, and even lead to reduced costs of capital.14 As illustrated in Figure 16.3, opportunities for firms to capture positive externalities aren’t just about transferring benefits from society to shareholders. By providing appropriate incentives for value-creating activities, they encourage businesses to provide more of them.

Risks from Overlooked Dependencies Natural and social capital provide businesses with factors of production (such as land and labor) and inputs to production (raw materials and energy), as well as the general conditions they need to operate successfully (stable climatic conditions, clean air and water). In many cases, business dependencies are well understood and actively managed. This is particularly true when the price a company pays for an ecosystem service or physical

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Figure 16.3 Capturing positive externalities can be a win–win. Here the balance of benefits shifts from society to private interests, but the sum total of benefits increases.

input is a reasonable reflection of its cost of supply and when the supply chain is short and transparent. However, if inputs are not properly priced or supply chains are long and complex, important dependencies can go unnoticed. Many industries have clear dependencies on natural capital. Forests supply timber, purify water, yield genetic resources, and help regulate the climate. River systems provide fresh water, energy, and recreation opportunities. Wetlands filter waste, mitigate floods, and serve as nurseries for commercial fisheries. And they do all of these things “for free.” Historically it’s only when they’ve stopped doing these things that businesses have taken notice. As an example, water shortages in the U.S. Pacific Northwest affected the price and availability of two critical inputs for a major beer producer. Barley prices increased in response to reductions in the amount of water available for irrigation. Meanwhile, the availability of aluminum for cans fell as smelters, which rely on low-cost power from hydroelectric dams, reduced output when electricity prices spiked during a drought.15

Understanding and Embracing Dependencies to Co-Create Value In the old world of narrowly focused profit maximizing firms, dependency was synonymous with risk. And it’s certainly true that the kind of invisible dependencies described above continue to create substantial business risks today.

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But in today’s interconnected world, with new business models that rely on interactions between the capitals, co-creation, and symbiosis, the right kind of dependencies can be actively embraced to generate additional corporate and societal value. For example, a water utility in Oregon saved $50 million by planting streamside trees to regulate water temperature with shade rather than opting for the conventional solution, more expensive and less long-lived automated chillers.16 In another example, a global car company partnered with a Brazilian environmental organization to promote sustainable mixed-use agriculture in its supply chain. This helped farmers achieve a fourfold increase in production of coconut fiber, an alternative filler material for seats and headrests. With reduced risk of input shortages, the company was able to switch away from plastic fillers. Alongside environmental benefits and improved returns for farmers, they also realized 5% cost savings.17

Harnessing Breakthrough Ideas and Disruptive Technologies for Planetary Health As the scale of negative externalities and the consequences of environmental degradation become more evident and more costly, opportunities for completely new types of business—ones that directly address planetary health challenges—are rapidly emerging. We see the evidence of this in particular through the circular economy movement. This movement aims to design out waste and pollution by redesigning products, and even buildings, so that they can be easily disassembled and repurposed or reused—so-called design for disassembly. In addition, it aims to keep products and materials in use and to regenerate natural systems,18,19 all with health benefits.20 The circular economy movement goes so far as to characterize eco-efficiency efforts as simply “doing less bad” and to relabel many forms of recycling as downcycling (whereby successive generations of a material have progressively lower value uses), in the process challenging us to seek transformative solutions rather than incremental changes. Where the presence of (often longstanding) negative externalities intersects with the emergence of new technologies, there may be opportunities to reimagine whole industries. For example, the problems associated with single-use, throwaway plastic packaging are well known. At least two sources of negative externality are present here. One is in production: The use of virgin polymers to make plastic from fossil oil doesn’t price in scarcity or the negative impacts of extraction. The other, more significant externality is in consumption: The use of throwaway packaging doesn’t price in the harms of throwing it away: the scourge of littering, harm to our oceans and biodiversity, and the GHGs emitted as it degrades or is incinerated. Despite these issues, the sheer convenience of cheap, versatile, sterile, single-use plastic has been hard to match for most packaging applications.

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However, there are some signs that this may be changing, aided by changing consumer attitudes toward plastic and measures such as mandatory charging for plastic bags, enabled by digital coordination platforms and cross-sector collaborations that are seeking to make durable, reusable packaging as convenient and inexpensive as plastic. One example is Loop, a new zero-waste platform from a coalition of major consumer product companies that launched its first pilots in 2019.21 The platform aims to make branded consumable products available in reusable containers delivered direct to the customer’s door. When finished, the container goes in a personal reuse bin, which is picked up for delivery back to a cleaning and sterilization facility so that it can be refilled. Although this new system does create additional transport and cleaning requirements, the partners behind the project claim that the overall environmental costs are 50%–75% lower than for conventional single-use packaging. Much has also been made of the so-called fourth industrial revolution22 (based on new computing power, artificial intelligence [AI], and other exponential technologies) and its potential to transform the global economy and societies beyond recognition. A dedicated group of companies, international organizations, and individuals have been actively exploring how these new technologies, particularly AI, can be purposefully harnessed for the benefit of the earth and future generations. A 2018 report by the World Economic Forum and consulting firm PwC identifies a range of game-changing AI applications to address some of our planet’s greatest challenges, including autonomous and connected electric vehicles, distributed energy grids, smart agriculture and food systems, and reinforcement learning for Earth science breakthroughs.23 While acknowledging the many challenges ahead, the report’s authors conclude on a positive note: We live in exciting times. It is now possible to tackle some of the world’s biggest problems with emerging technologies such as AI. It’s time to put AI to work for the planet.

A Blueprint for Planetary Health Businesses Drawing on the preceding sections, we can articulate a five-point blueprint for business success in the transition toward planetary health. • Identify, measure, and value positive and negative externalities along the value chain. • Treat negative externalities as risks to be managed and mitigated proactively. • Treat positive externalities as opportunities to be maximized and internalized where possible. • Identify and value dependencies on the wider capitals (natural, social, human, and intellectual) along the value chain.

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• Seek opportunities to collaborate and invest in these wider capitals to improve both private and societal returns. • Evaluate performance along the value chain against the planetary boundaries to identify where further action is critical. • Screen product and service portfolios based on their contribution to delivering on planetary health (their effects on human health and wellbeing as well as their impacts across the planetary boundaries). • Seek to futureproof portfolios by prioritizing products and services with positive contributions to planetary health and scaling back on those that have less favorable impacts. • Seek out the breakthrough ideas and disruptive technologies that can be harnessed to address specific planetary health challenges. • For existing businesses, study the externalities along your value chain and how they intersect with new technological developments. • For breakthrough entrepreneurs, take aim at the greatest planetary health challenges, the greatest environmental inefficiencies caused by our current take–make–dispose economic model, secure our future, and make your fortune by solving them. The final two sections of this chapter feature more in-depth examples from companies that are pursuing planetary health goals. Case Studies 16.1 and 16.2 provide two very different examples of large established businesses that are experimenting with new ways to transform their existing business models to align with planetary health. Case Study 16.3 provides an example of a business with an innovative model designed to exploit the opportunities of a transition to planetary health.

Case Studies: Transforming Existing Business Models to Deliver on Planetary Health Case Study 16.1: Kering Global luxury group uses advanced natural capital measurement, valuation, and management tools alongside active supply chain engagement to advance planetary health. Kering pioneered environmental profit and loss (EP&L) accounting, supported by professional services firm PwC UK, as an advanced business management tool that provides in-depth analysis of the environmental impacts of a company’s activities. The EP&L measures and values environmental impacts across Kering’s own operations and its entire international supply chain. By doing so it helps Kering to translate environmental impacts into a language business decision makers can readily understand, to compare between different types of impact and to elucidate differences in environmental performance between brands, business units, and locations.

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As a result Kering is able to identify the most significant drivers of impact along its value chain and implement targeted projects to improve impacts (e.g., development of new manufacturing processes, innovations in material use, and new multistakeholder collaborations). Figure 16.4 shows how Kering’s 2017 impacts are distributed along its value chain. The majority of Kering’s impacts are generated in its supply chain (90%), and in particular from the production and processing of raw materials, which together represent 76% of

Figure 16.4 The contribution of supply chain tiers to Kering’s environmental profits and losses (EP&L), divided by impact area. Small-scale changes in sourcing options, such as replacing materials with recycled alternatives, can result in tangible reductions in negative impacts. Source: Kering. Environmental Profit & Loss, 2017 Group Results. 2018. https://keringcorporate. dam.kering.com/m/5be02c657921b940/original/Report-Kering-Environmental-Profit-Loss -2017-Group-Results.pdf

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the total. Kering’s own operations represent only 10% of the impacts. With the knowledge gained from the EP&L Kering has shifted the focus of its sustainability efforts further upstream toward primary production and processing activities. Because the supply chain is made up of thousands of independent businesses, many of which serve multiple customers, Kering is also collaborating with its peers and across sectors in an effort to address environmental challenges. Figure 16.5 shows the contribution of major groups of raw materials to Kering’s overall 2017 EP&L, as well as the volume of each material sourced across the group.

Figure 16.5 The contribution of major groups of raw materials to Kering’s environmental profits and losses and the quantities of raw materials involved. Leather is the highest-quantity material produced and the highest driver of impacts, principally via land use and greenhouse gas emissions. The quantities of animal fibers (e.g., wool and cashmere) and metals (e.g., brass and gold) used are small, but they have comparatively large impacts on land use and water pollution, respectively. Analyses such as these reveal opportunities to reduce environmental impacts. Source: Kering. Environmental Profit & Loss, 2017 Group Results. 2018. https://keringcorporate. dam.kering.com/m/5be02c657921b940/original/Report-Kering-Environmental-Profit-Loss -2017-Group-Results.pdf

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Among the raw materials it uses, leather is the greatest driver of impacts, followed by animal fibers such as wool and cashmere and metals such as brass and gold. These last two material categories offer significant possibilities to drive impact reduction. Interventions such as replacing materials with recycled alternatives can reduce negative environmental impacts. Figure 16.6 shows one example of how the information generated in the EP&L can be used to inform decisions about sourcing locations, material choice, and product design, as well as highlighting areas where interventions to reduce impacts may be most beneficial.

Figure 16.6 The environmental impacts of choices in design, sourcing, and manufacturing. In this example, Kering luxury shoes, the environmental impact varies by a factor of 12 from lowest to highest, with the largest impacts relating to type of leather used (the impact of alligator leather is nearly ten times higher than that of pig leather) and the site of manufacturing (impacts in Asia are ten times higher than in Europe). Source: Kering. Environmental Profit & Loss, 2015 Group Results. 2016. https://keringcorporate. dam.kering.com/m/43f7e21141014b9f/original/Report-Environmental-Profit-Loss-2015-Kering -Group-Results.pdf

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This case demonstrates the potential for innovative natural capital measurement and valuation to inform business decisions in support of planetary health goals.

Case Study 16.2: Aguas Andinas Largest water utility company in Chile pioneers circular wastewater treatment approach using new biofactories. Aguas Andinas, Chile’s largest water utility company (controlled by the Spanish group SUEZ), is transforming Santiago’s three wastewater treatment plants into “biofactories” that convert wastewater and sewer sludge into energy (electricity, natural gas, and thermal energy) while also producing fresh water to maintain in-stream flows for aquatic species and extracting nitrogen and phosphorus to fertilize local farmland. The project was launched in 2017 to trial innovative circular wastewater treatment solutions and to push the boundaries of human health and environmental preservation standards in the sector. In 2017, energy recovery from sewer sludge led to the production of 49 gigawatt-hours of electricity, 177 gigawatt-hours of natural gas, and 84 gigawatt-hours of thermal energy in Santiago, as well as 137,000 tons of agricultural fertilizer.24 If the company achieves its aims, all three treatment plants will be zero-waste, energy self-sufficient, and carbon neutral by 2022. Analysis by the Financial Times in 2019 indicated that Aguas Andinas’s average net profit margin over the previous 5 years (26%) exceeded that of its peers in the region, suggesting that the company’s focus on the environment has not held it back commercially.25 This case highlights how a company in the wastewater sector—a sector that typically produces significant volumes of GHGs, other air pollutants, and hazardous waste—can develop a strategy that is compatible with planetary health. Depending on the success of the company’s new biofactories it may even have the potential to be actively beneficial for planetary health. This case is explored in much more detail in Planetary Health Case Studies: An Anthology of Solutions (https://islandpress.org/books/planetary-health).

Examples: Developing New Business Models to Deliver on Planetary Health Case Study 16.3: Beyond Meat Beyond Meat was founded in 2009 with a plan to create plant-based burgers, sausages, and other meat products directly from plants, indistinguishable in taste and texture from traditional meat products. By 2019 its products were on sale in more than 32,000 grocery stores, restaurants, and other outlets, and the company claimed to have sold more than 25 million of its Beyond Burgers in the period from 2016 to 2018 alone. Up to the time of writing, investors remained positive about the firm’s growth prospects after a series of strong trading updates. Following its initial public offering (IPO) in May 2019, Beyond Meat Inc.’s stock price rose 163% on the first day of trading (the strongest first-day

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performance in almost two decades), and after briefly exceeding nine times its initial IPO price in July 2019, the stock price appeared to have stabilized at around three times its initial IPO price in December 2019. Whether or not these valuations prove sustainable for Beyond Meat Inc. itself, industry analysts are almost universally predicting huge growth for the meat alternatives market as a whole, with forecasts of sector revenues by 2030 ranging between $40 billion26 and $140 billion.27 Industrial beef production is the antithesis of planetary health (as described in Chapter 5). Large-scale beef production in feedlots produces large quantities of climatewarming GHGs, mostly in the form of methane from fermenting plant matter in cows’ stomachs.28,29 Excessive use of antibiotics in the industry has been linked to growing antimicrobial resistance,30,31 which presents as risk to human as well as animal health. Feeds such as corn and soy are typically grown in intensive monoculture formations with synthetic pesticides, fungicides, and fertilizers. The environmental impacts of the majority of cattle raised outdoors are not necessarily better; extensive grazing of former rangelands has resulted in widespread land degradation and the release of significant volumes of carbon from soils over the course of many decades.28 Nearer the tropics, pristine rainforest has been cleared to make way for pasture or feed crops.28 Beyond Meat (Figure 16.7) aims to address these negative impacts by providing a mass market alternative to conventional meat that is at least as healthy, tasty, and

Figure 16.7 Innovative products such as the Beyond Burger offer environmental advantages over conventional meat production. Source: Wikimedia, Creative Commons, license CC BY-SA 4.0

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affordable but has far lower impact. According to a life-cycle analysis from the University of Michigan’s Center for Sustainable Systems, the production of a Beyond Burger uses 99% less water, 93% less land, and 46% less energy and emits 90% less GHG than that of a typical beef burger.32 The nutritional benefits of such alternative meats relative to conventional meat varies with the specific ingredients. Although the environmental benefits of its products are clear, there are still consumer perception issues for the sector to overcome if it is to achieve the mass market scale and transformative outcomes it hopes to deliver. This case highlights one of the many opportunities for innovative new businesses to emerge to help us address key planetary health challenges.

Conclusions In responding to the needs and wants of populations, businesses have been both a key driver of humanity’s advancement and a key instrument of the planet’s destruction. However, things are changing. The forces driving the internalization of negative externalities are strengthening, making dated business models that rely on externalizing environmental costs less profitable. At the same time, opportunities for companies to work with nature—to embrace ecological dependencies and invest in enhancing natural capital—are becoming increasingly attractive and widespread. Supported by these trends and enabled by new technologies, transformative new business models are also emerging that seek to address planetary health challenges head on. Despite these changes, not all businesses see value in acting voluntarily to help drive a transition toward planetary health. Resistance is particularly evident in established sectors that fundamentally struggle to operate within planetary boundaries, as well as sectors whose products are now known to be detrimental to human health and wellbeing. In these instances, new and effective global governance arrangements, new regulatory measures, concerted but creative public campaigns, and conscious choices by consumers will be needed to provide the necessary impetus for change. Most would agree that delivering on planetary health presents one of the ultimate challenges for global governance. Planetary health is multidisciplinary and therefore multi-institutional, demanding a pluralistic and polycentric approach. To succeed at a global scale, multilateral institutions will need to be mobilized, and agile, cooperative forms of governance will be necessary, together with strong and effective leadership. As illustrated through this chapter, the emerging economics of planetary health introduced in Chapter 15 can help devise better models of governance for global and local commons and design new global and local policy instruments to deliver on planetary health goals. It can also help big established companies transform their business models into net promoters of planetary health and identify or create opportunities for disruptive new business models to emerge that directly address planetary health challenges.

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Authors Will Evison is a sustainability economist based in the United Kingdom. He works collaboratively with companies, governments, and nongovernment organizations around the world to help them solve important sustainability problems. Will was a leading author of the Natural Capital Protocol, an editor and author of The Economics of Ecosystems and Biodiversity report for Business and Enterprise, and a longstanding advisor to the World Business Council for Sustainable Development, the World Economic Forum and the Natural Capital Coalition. Sam Bickersteth was executive director of the Rockefeller Foundation Economic Council on Planetary Health at the Oxford Martin School, 2018–2019. He was previously chief executive of the Climate and Development Knowledge Network, supporting climate research and policy for developing countries, and has worked for the University of Oxford, PwC, DFID, and Oxfam. He has 30 years of experience living and working in developing countries across Africa, Asia, and Latin America.

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Hardin G. The tragedy of the commons. Science. 1968;162(3859):1243–1248.

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Ostrom E. Governing the Commons: The Evolution of Institutions for Collective Action. Cambridge, UK: Cambridge University Press; 1990.

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Green BA. Lessons from the Montreal Protocol: guidance for the next International Climate Change Agreement [comment]. Environ Law. 2009(1):253–284.

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Apostolopoulou E, Adams WM. Biodiversity offsetting and conservation: reframing nature to save it. Oryx. 2017;51(1):23–31.

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Clift R, Sim S, King H, et al. The challenges of applying planetary boundaries as a basis for strategic decision-making in companies with global supply chains. Sustainability. 2017;9(2):279.

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Funk M. Windfall: The Booming Business of Global Warming. New York, NY: Penguin; 2014.

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Seba T. Clean Disruption of Energy and Transportation: How Silicon Valley Will Make Oil, Nuclear, Natural Gas, Coal, Electric Utilities and Conventional Cars Obsolete by 2030. Silicon Valley, CA: Clean Planet Ventures; 2014.

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Macalister T. £45m battle of Dibden Bay fails to sink ABP hopes. Guardian. September 2, 2004. https://www.theguardian.com/business/2004/sep/02/environment.society.

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Verdin M. AB Ports shares sink after plan rejected. Times of London. April 20, 2004. https: //www.thetimes.co.uk/article/ab-ports-shares-sink-after-plan-rejected-3g3tb8fhx97.

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12. BBC. Cola companies told to quit India. BBC News. January 20, 2005. http://news .bbc.co.uk/2/hi/south_asia/4192569.stm. 13. Potts J, Wilkings A, Lynch M, McFatridge S. Standards and the Blue Economy. Winnipeg, MB, Canada: International Institute for Sustainable Development; 2016. https://www. iisd.org/ssi/standards-and-the-blue-economy/. 14. Clark GL, Feiner A, Viehs M. From the Stockholder to the Stakeholder: How Sustainability Can Drive Financial Outperformance. Oxford, UK: University of Oxford and Arabesque Partners; 2015. 15. GEMI. Case study: Anheuser-Busch Inc. Exploring water connections along the supply chain. 2002. http://gemi.org/water/anheuser.htm. 16. Niemei E, Lee K, Raterman T. Net economic benefits of using ecosystem restoration to meet stream temperature objectives. ECONorthwest. 2007. 17. Mugica Y. Partnering for mutual success: DaimlerChrysler–POEMAtec alliance. In: Teaching Cases from Kenan-Flagler Business School, University of North Carolina. Chapel Hill, NC: University of North Carolina; 2004. 18. Stahel WR. The circular economy. Nature. 2016;531(7595):435–438. 19. Material Economics. The Circular Economy: A Powerful Force for Climate Mitigation. Stockholm, Sweden: Material Economics Sverige AB; 2018. https://europeanclimate .org/the-circular-economy-a-powerful-force-for-climate-mitigation/. 20. WHO. Circular Economy and Health: Opportunities and Risks. Copenhagen, Denmark: World Health Organization, Regional Office for Europe; 2018. http://www.euro.who.int /en/publications/abstracts/circular-economy-and-health-opportunities-and-risks-2018. 21. Peters A. A coalition of giant brands is about to change how we shop forever, with a new zero-waste platform. Fast Company. January 26, 2019. https://www .fastcompany.com/90296956/a-coalition-of-giant-brands-is-about-to-change-how-we -shop-forever-with-a-new-zero-waste-platform. Accessed October 2019. 22. Schwab K. The Fourth Industrial Revolution. New York, NY: Crown Publishing; 2016. 23. WEF. Harnessing Artificial Intelligence for the Earth. Geneva, Switzerland: World Economic Forum in Collaboration with PwC and Stanford Woods Institute for the Environment; 2018. http://www3.weforum.org/docs/Harnessing_Artificial_Intelligence_for_the _Earth_report_2018.pdf. 24. UNFCCC. Santiago Biofactory: Chile. 2018. https://unfccc.int/climate-action /momentum-for-change/planetary-health/santiago-biofactory-chile. 25. Financial Times. Equities: Aguas Andinas SA. 2019. https://markets.ft.com/data /equities/tearsheet/profile?s=AGUAS-A:SGO. 26. Scipioni J. Alternative meat industry headed toward a $40B market by 2030, analyst says. FOXBusiness. 7 May 2019. https://www.foxbusiness.com/features/the -alternative-meat-industry-headed-toward-a-40b-market-by-2030-analyst-says.amp. Accessed October 2019. 27. Franck, T. Alternative meat to become $140 billion industry in a decade, Barclays predicts. CNBC. 23 May 2019. www.cnbc.com/amp/2019/05/23/alternative-meat-to -become-140-billion-industry-barclays-says.html Accessed October 2019. 28. FAO. Livestock’s Long Shadow: Environmental Issues and Options. Rome: Food and Agriculture Organization; 2006.

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29. Matthews C. Livestock a major threat to environment [press release]. FAO, 29 November 2006. http://www.fao.org/3/a0701e/a0701e00.htm. 30. National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS). Antibiotic Resistance. https://www.cdc.gov/narms/faq.html. Accessed January 2020. 31. FDA. 2009 Summary Report on Antimicrobials Sold or Distributed for Use in Food-Producing Animals. Food and Drug Administration, Department of Health and Human Services; 2014. https://www.fda.gov/media/79581/download. 32. Heller MC, Keoleian GA. Beyond Meat’s Beyond Burger Life Cycle Assessment: A Detailed Comparison between a Plant-Based and an Animal-Based Protein Source. Ann Arbor, MI: University of Michigan Center for Sustainable Systems; 2018. http://css.umich.edu /sites/default/files/publication/CSS18-10.pdf.

Part 4 Saving Ourselves, Saving Our Planet

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17 Planetary Health Ethics Alexander Foster, Jennifer Cole, Ivica Petrikova, Andrew Farlow, and Howard Frumkin

For many years, ethics has been a staple of both medical and environmental thought. On the medical side, the Hippocratic precept to “do no harm” evolved into a contemporary framework of bioethics based on four pillars:1,2 • Autonomy: Respecting the decisions (self-determination) of adults, which entails telling the truth, respecting privacy, protecting confidential information, and obtaining consent for interventions. • Beneficence: Acting for the benefit of others, which entails protecting the rights of others, preventing harm to others, and rescuing people in danger. • Nonmaleficence: Avoiding harming others (consistent with the Hippocratic precept). • Justice: Fair distribution of opportunities and other goods. The term bioethics, as proposed by biochemist Van Rensselaer Potter in 1970, referred to a combination of biology with “humanistic knowledge” to form a “science of survival.” Ethics, Potter wrote, “cannot be separated from a realistic understanding of ecology in the broadest sense. Ethical values cannot be separated from biological facts. We are in great need of a land ethic, a wildlife ethic, a population ethic, a consumption ethic, an urban ethic, an international ethic, a geriatric ethic, and so on.”3 Despite this broad and prescient framing, bioethics has in practice been limited in large part to questions of health care.

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On the environmental side, early conservationists such as George Perkins Marsh (1801–1882) and John Muir (1838–1914), responding in part to the ravages of industrialization on natural places, called for an ethic of environmental stewardship. In doing so, they railed against what historian Lynn White, a century later (White, 1967), characterized as a longstanding Judeo-Christian attitude of domination and exploitation of the natural world (perhaps without appreciating that humans could fundamentally alter that world). With the rise of environmentalism in the second half of the twentieth century came calls for a new ethos of planetary stewardship, one “founded on a basic change of values and goals at individual, national and world levels.”4 Ecologist Garrett Hardin (1915–2003), in his famous 1968 essay on the tragedy of the commons, raised moral concerns over the unfettered use of common-pool (free for all to use) resources.5 These concerns were acknowledged even by opponents such as economist Elinor Ostrom (1933– 2012), who showed that communities can and do manage shared resources sustainably under favorable circumstances.6 Many different kinds of ethical approaches to the Anthropocene have been proposed. Holmes Rolston, for example, advocates an “Earth ethic,” one that regards Earth as a “valued residence in a community of life.”7 Miles and Craddock similarly argue for “biome ethics” grounded in “the global biome with its comprehensive relationships between human activity, all life forms, and the environment,”8 which encourages humanity to think through the concepts of connectivity, the human and nonhuman continuum, and shared suffering. Consistent across these different propositions are the needs to position humanity within both its ecological and social contexts so as to enable stewardship; to extend ethical thinking to longer timeframes, larger spatial scales, and the more-thanhuman world; and to implement economic and legal systems that advance both justice and sustainability.8–10 Such an expansion of ethics is vital to avert what philosopher Stephen Gardiner (2006) refers to as a “perfect moral storm.” For Gardiner, three attributes make climate change (and, we might add, global environmental change more generally) the problem that it is: dispersion of cause and effects (e.g., emissions from any location affects all locations), fragmentation of agency (multiple actors all responsible to varying degrees), and institutional inadequacies (the institutions, particularly political institutions, currently in place are insufficient to deal with the task at hand). Furthermore, the longevity of CO2 in the atmosphere skews problems into the future, turning climate change into a backloaded problem in which the impacts are most forcefully felt by those a few generations into the future rather than by those most responsible for greenhouse gas emissions. Gardiner argues that these three aspects conspire with intergenerational complacency, the demand for unreasonable certainty about intrinsically uncertain projections, deliberate deception by vested interests, and selective attention to lead people to commit

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otherwise unspeakable actions: a perfect moral storm. From a planetary health perspective, we might add to this list that our impacts on other people or future generations can be quite indirect, mediated through complex interactions with our natural environment, and therefore may be less visible than actions that directly imperil others. In the face of such a storm, planetary health aims to advance the understanding of the links between human-driven changes to the planet and their consequences for people and planetary systems and to develop appropriate solutions to the challenges identified. To do this, it needs an ethical framework against which identified solutions can be evaluated. Longstanding ethical frameworks serve well, but planetary health insights—the global connectedness of all people, such that my decision about what to eat in London affects the well-being of a child in India, and the global connectedness of people with the biosphere, such that my decision about what to eat in London may contribute to Amazon deforestation—call for novel ethical thinking. A starting point for planetary health ethics was proposed in 2019,11 building on the Statement of Principles in the Canmore Declaration of 2018,12 which itself drew from the 1986 Ottawa Charter for Health Promotion.13 These affirm the urgent need to consider the health of people, places, and the planet as intimately connected pieces of a larger whole. It is worth clarifying the subtle differences between the terms principles, ethics, morals, and values. Principles are aspirational14 but also generally abstract. Morals are broadly accepted beliefs about what is right or wrong, which can be codified into ethics, a more practical, tangible system or set of rules explicitly adopted by a group of people such as a professional society. Values, like morals, guide decisions, distinguishing right and wrong, good and bad, but unlike morals, values can vary between individuals. I can respect you if your values differ from mine, but I will probably lose my respect for you if you act immorally. Ethical standards can be adhered to (or violated), and they guide our personal values and the choices we make in our daily lives, such as, “Should I drive a car that emits greenhouse gases when I could walk?” Or, “Should I spend money on entertaining myself when I could give that money to the poor?”15 Such decisions routinely entail choosing one course of action and its consequences over another course of action with different consequences. Ethics do not provide incontrovertible answers. They can be highly controversial and politically loaded, and finding consensus on what they should be may not be easy, particularly in a pluralistic world.16 However, they can provide a basis for negotiating in situations where particular actions are not the preferred first choice of all actors.16 In this sense, the notion of ethics carries with it something bigger than the individual, pushing us toward actions that are not (only) for self-interest.15 Ethical judgments thus empower us to transcend our own likes and dislikes and to reason with others as to why they should do the same. Inherent in traditional ethics are

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concepts such as honesty, prudence, avoiding harm, and concern for others.16 If we can extend the notion of “others” to future generations, to other species and to Earth itself, we can more easily ensure the “sustainable vitality of all systems” called for by the Canmore Declaration.12 Ethics thus provide a part of the principled framework for building a holistically healthier world. This chapter proceeds as follows. First, it clarifies some basic considerations for thinking through planetary health ethics. Second, it proposes five ethical positions for planetary health: intergenerational justice, more-than-human rights, distributive justice, the precautionary principle, and the right to know. For each of these, actions points are suggested as examples of what can be done to operationalize the ethical positions proposed. It then closes with some general comments about human rights and potential future ambitions of planetary health ethics.

Foundations for Planetary Health Ethics Against a backdrop of both medical and environmental ethics, any approach to planetary health ethics should have certain features. First, ethical statements must be useful. They should be clear enough that they can guide decision making, particularly in highly complex or ambiguous situations and those that require compromise. We will increasingly confront a world in which the choices we would most like to make are unavailable, so any decision guidelines must effectively help navigate thorny, even paralyzing dilemmas, assessing and “maximizing” the remaining choices.17 Second, ethical statements must be usable. They should be framed in ways that are accessible and workable for both policymakers and members of the public. They must be relevant to the problems people actually confront. And they must be regarded as legitimate by those whose actions they will guide. Third, ethical statements must be used. They cannot be decorative or disingenuous, the rhetorical equivalent of greenwashing; ethical talk without commensurate action is not ethical. Ethics must be put into practice and must demonstrably affect outcomes. In practice this often means codifying ethics and applying them through social norms, legal requirements, or other mechanisms. Fourth, ethical statements must be universal. Just as planetary health must be farreaching, the ethics that inform it must be widely agreed and accepted. If fossil fuel extraction, widespread deforestation, or profligate meat consumption is acceptable in one place but not another, that poses challenges of both principle and practice in meeting global goals. It is here that ethics has particular purchase by providing a universal navigational tool through a series of options that may require compromises from some or all of its stakeholders.

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Ethical Positions for Planetary Health Intergenerational Responsibility Intergenerational responsibility is the idea that those alive at any point in time have a duty to leave the world intact for those who come after them. This is a position recognized by many authors,10,18,19 and it has become axiomatic in planetary health, which views each generation as the custodians, not the masters, of the biosphere, responsible to future generations as well as to its own. Perhaps surprisingly, there is robust debate about the concept of intergenerational responsibility; some philosophers and legal scholars argue that future generations do not exist and therefore cannot “have” anything, including rights, that there is no reciprocity between present and future generations (a prerequisite for responsibility between groups), and that there is uncertainty regarding what future generations would want.20,21 Gardiner asserts the alternative in his concept of the perfect moral storm: It becomes unethical for the present generation not to act when inaction increases both the suffering of future generations and the likelihood of having to make tragic choices.22 Some have suggested that the concept of intergenerational responsibility might be less abstract and more tangible if reduced to the “scale of the family”20— roughly three generations on either side of the present generation, an interval during which people have personal relationships (and accountability) with both their immediate forebears and their progeny.23

Action Points • Develop jurisprudence and enact laws that establish rights for future generations. Examples include litigation such as Juliana vs. United States24 and legislation such as the Welsh Well-being of Future Generations Act (2015). • Introduce children to sustainable practices and outlooks from the earliest age so that actions and attitudes conducive to planetary health become normative. • Empower and heed youth voices such as those that have given rise to the School Strike movement, in recognition of their claims to a legacy of an intact planet.

Extending Rights to the More-Than-Human World A central question in environmental ethics concerns the moral standing of nonhuman species and of the biosphere more generally.25,26 Debate about this question has turned on the difference between instrumental value and intrinsic value. Instrumental value is grounded in the means to some other end. For example, pollinators would have value not in and of themselves but because of their role in producing food for people. Intrinsic value holds that something has value in and of itself—a belief that implies a duty on the part of others to respect its right to be. For environmentalists, this has been a primary rationale for nature conservation.

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An anthropocentric approach to environmental ethics is instrumental, holding that only humans have intrinsic value (or, in softer form, that human value exceeds the value of nonhuman things).27 This is an ancient perspective; Aristotle, for example, wrote that “nature has made all things specifically for the sake of man.”28 Similarly, Martin Heidegger (1889–1976) saw animals as tools that are “at hand.”29 Opposing this approach are arguments made in the late twentieth century by animal rights advocates such as Peter Singer.30,31 These writers viewed animals as subjects, rather than objects, of a life, meaning that they have inherent value and moral standing.15,32 Some philosophers33,34 and legal scholars35–37 have elaborated these arguments, even arguing for individual animals to have their rights recognized.38 Planetary health brings new insight to this debate through its focus on the intimate relations between the biosphere and human wellbeing—rejecting a bright distinction between animals, landscapes, and ecosystems on one hand, and humans on the other. This corresponds to a third ethical category that has arisen alongside instrumental and intrinsic value, introduced by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), called relational value.39 Proponents note that the dichotomy between instrumental and intrinsic has led to a stark choice: between marketbased valuation and conservation without much consideration of humans.40–42 Relational value reflects the importance attributed to meaningful and sought-after relations (and responsibilities) between humans and between humans and nature. As such, it departs from an economic valuation framework, such as ecosystems services analysis, more typical of instrumental value. Relational value accommodates the different relations with nature of different cultures and societies, including Indigenous people, and thus promotes pluralism. There are echoes of planetary health in emerging legal initiatives on the “rights of nature.”43,44 Often such efforts incorporate Indigenous traditions. In 2008, Ecuador became the first nation to recognize rights of nature in its constitution—including the rights to exist, persist, maintain, and regenerate its vital cycles.45 In New Zealand, the Te Urewera Act (2014) and the Te Awa Tupua Act (2017) established the rights of the Te Urewera National Park and the Whanganui River, respectively, turning these places into legal personalities, represented by a system of joint Indigenous and government guardianship.44,46 In 2017, a court in the northern Indian state of Uttarakhand cited the New Zealand precedent in conferring the status of living human entities on the Ganges and its main tributary, the Yamuna. In the United States, several jurisdictions have enacted rights of nature ordinances, beginning with Tamaqua Borough, Pennsylvania in 2006.47 These legal statements of rights of nature, though diverse, share several principles: recognizing human impacts on the natural world, balancing human and nonhuman rights, and providing for restoration of disrupted ecosystems.

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Action Points • Acknowledge the value of more-than-human entities and therefore work to reduce one’s own individual impacts on those more-than-human entities (e.g., reduce the use of palm oil–based products that contribute to deforestation, reduce meat consumption, reduce personal contributions to plastic pollution of both the land and the sea). • Partner with Indigenous peoples to incorporate their perspectives and traditions within policies regarding protection of the more-than-human world. This must be done in a manner that is not superficial but in a way that respects and seeks to learn from these Indigenous peoples. • Seek to work with local interest groups to develop rights-of-nature policies and laws, not only for individual species, but for ecosystems as a whole. Such action is especially salient for communities that are directly dependent on particular ecosystems, such as coastal, rural, and Indigenous communities.

Distributive Justice Distributive justice is concerned with how goods, services, and entitlements should be apportioned in a just society.* This has been a concern for as long as people have formed societies. Deliberations on distributive justice date from Aristotle (384–322 BC) to Enlightenment thinkers such as Immanuel Kant (1724–1804) and David Hume (1711–1776), through to the contemporary philosopher John Rawls (1921–2002). Distributive justice is keenly relevant to planetary health. Our world features massive inequities in wealth and income between and within countries, with some of the disparity widely viewed as unethical. Moreover, the prospect of scarce resources—land, water, and more—becoming even more scarce threatens to deepen inequalities. Three aspects of distributive justice are especially salient for planetary health: • Inequalities in who has contributed to planetary degradation; • Inequalities in who is most harmed by planetary degradation; and • Opportunities to rectify injustices while addressing planetary degradation. There is considerable asymmetry in which countries have contributed to environmental degradation. As shown in Figure 17.1, the wealthy countries of the Global North have contributed the bulk of greenhouse gases to the atmosphere, and the poor countries of the Global South are disproportionately at risk. But as dramatic as the disparities in *This can be considered as a base definition for distributive justice. For further information on what a just society is, to what extent inequality might have a role in such a society, and on what grounds this inequality would be acceptable, see Olsaretti S. The Oxford Handbook of Distributive Justice. Oxford, UK: Oxford University Press; 2018.

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Figure 17.1 Cumulative national carbon dioxide emissions, 1950–2000 (upper panel) and distribution of four climate-related causes of death (malaria, malnutrition, diarrhea, and flood-related fatalities) (lower panel). In this cartogram, each nation’s size is proportional to its impact. The disconnect between the countries that drove climate change and those that suffer from it is dramatic. Source: Patz JA, Gibbs HK, Foley JA, Rogers JV, Smith KR. Climate change and global health: quantifying a growing ethical crisis. EcoHealth. 2007;4:397–405.

Figure 17.1 are, they do not tell the full story. First, many of the emissions assigned to countries such as China relate to goods produced for export to wealthy countries,48 so arguably they should be attributed to the wealthy countries. Second, the geopolitical arrangements that give rise to these disparities rest on a history of colonialism and exploitation49 that is ongoing—a history itself rife with ethical transgressions.

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Ethical concerns about disproportionate contributions to planetary damage that will profoundly affect human lives apply to the individual level as well as to the national level. If a person chooses to live extravagantly—to fly long distances frequently, to eat large quantities of meat, to build a home out of old-growth redwood, or to use technologies that require extensive mining for rare earth elements—is that ethical? Does it violate the core principle of nonmaleficence if excessive consuming contributes to harming others?50,51 One proposed solution to asymmetric contributions to environmental degradation is called contract and converge.52 On a global level, this entails reducing overall CO2 emissions (or, in theory, other forms of environmental impact) to a sustainable level (contraction) and harmonizing all countries’ per capita emissions (convergence): Wealthy, high-emitting countries would reduce their emissions, while poor countries increase theirs, as their citizens become more prosperous. (Underemitters could sell their quotas to overemitters, as in a cap-and-trade scheme.) On the individual level, the question is whether people should keep their environmental footprints to within a “fair share”—a level defined as commensurate with everybody else also having access to a fair share while remaining within planetary boundaries.53,54 Both approaches involve ethical limits to consumption. Disparities in vulnerability to global environmental change are dramatic. These are well characterized in the case of climate change. At the national scale, small island states such as Kiribati and Tuvalu55 are especially vulnerable, as are flood-prone nations such as Bangladesh, nations due to become unbearably hot such as Iraq and Saudi Arabia,56 and many others. Within nations, people who are poor and disenfranchised—those already vulnerable to life’s vicissitudes—are especially vulnerable to heat, natural disasters, rising food prices, and other impacts (Figure 17.2).57 In certain parts of the world, women are more likely to be affected by these global environmental changes than are men.58 These disparities are not static; by disadvantaging the disadvantaged, environmental degradation deepens inequalities,59 in a classic vicious cycle. Finally, if there are ethical problems with both the legacy of planetary damage and the distribution of the suffering that results, what are the implications for adaptation and mitigation action? Do wealthy countries—the ones that have done most to cause the problem—carry a special responsibility for supporting poor countries in coping with environmental destruction? Several examples are instructive. An important climate change mitigation strategy is reducing emissions from deforestation and forest degradation (REDD). An enhanced approach, which includes conservation and enhancement of forest carbon stocks and sustainable forest management, is called REDD+. Case studies of REDD+ projects in Vietnam and Tanzania have found that they shift considerable responsibility for forest conservation onto local communities, as opposed to interrupting deforestation from infrastructure development and illegal commercial logging.60,61 Such an approach may unduly burden smallholder communities, devalue traditional ways of life, and leave structural causes of deforestation unchallenged.

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Figure 17.2 People stranded by Hurricane Katrina in New Orleans, 2005. Poor and ethnic minority communities were among those hit hardest by that disaster—a typical pattern. Source: Photo by Jocelyn Augustino (FEMA)

A more ethical approach might be for historically large contributors to climate change to shoulder responsibility themselves, effect needed system change (even at some expense to themselves), and support adaptation measures that protect those most affected. A second example pertains to when adaptation and mitigation fail: the concept of loss and damage (L&D). This refers to irreversible loss (e.g., disappearance of an island nation or the extinction of a locally important species of pollinator) or repairable damage (e.g., urban flooding or deforestation to create oil palm plantations) due to environmental change. Because low-income countries are disproportionately vulnerable to such L&D, some have called for providing them with financial assistance, compensation, or even reparations. The UN Framework Convention on Climate Change (UNFCCC) debated these issues beginning in the 1990s, including whether to make an L&D mechanism a “third pillar” alongside mitigation and adaptation. Small island states and least-developed countries advocated this move and wealthy nations resisted it—or at least resisted framing it as compensation or reparations. The ethical argument for a more robust L&D mechanism

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turns on the disparities in both responsibility for environmental change and capacity to recover from losses. Although there are practical difficulties in creating a compensation mechanism—such as the difficulty of attributing losses to specific causes and the difficulty of defining adaptation limits beyond which L&D are unavoidable—the major barrier has been the reluctance of wealthy nations to accept ongoing liability. In 2013 the UNFCCC created a mechanism for countries to report on climate change impacts including damages suffered (called, a bit inelegantly, the Warsaw International Mechanism on Loss and Damage Associated with Climate Change Impacts), but there remains no mechanism for compensation of poor nations by wealthy nations.62,63 A third example of a distributive justice challenge is environmental migration (see Chapter 8). Global environmental changes are rarely the sole cause of migration, but increasingly they contribute. If people are forced to leave their communities in Central America in part by the failure of the coffee crop, or if people are forced from their homes in Bangladesh by rising sea levels, is there an ethical responsibility in wealthy nations, which contributed to those changes, to accept immigrants? If so, does that ethical responsibility start when the future prospect of such migration becomes clear or only once such migration begins? Does the magnitude of that responsibility depend on the receiving nation’s contribution to the environmental changes that triggered migration? On its financial resources? On its ability to support a greater population? What is the role of anti-immigrant political sentiment in receiving countries? Do the migrants themselves have rights in this situation? What protections should be put in place to preserve the culture of peoples displaced by rising sea levels, when the land that formed the basis of their culture no longer exists? Currently, the definition of “refugee” in international law is based on persecution in the country of origin; should that definition be broadened to create entitlements for environmental refugees?64–67 If so, how does this labeling affect those who have been displaced?68

Action Points • Seek to eradicate poverty and achieve sustainable development through appropriate economic models. Such poverty eradication and sustainable development must occur in conversation with local communities, favoring grassroots sustainability through collective participation over top-down imposition of change. • Press governments to implement contraction and convergence policies at both the national and international scales, placing particular emphasis on historically largescale contributors. • Encourage governments and international agencies to open discussions about how the climate-related global migration of peoples might best happen so as to prevent panicked mass migration and virulent anti-immigration responses. • Work to develop an actionable L&D mechanism that can enable the process of compensation from wealthy nations to poor nations.

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The Precautionary Principle The precautionary principle is a modern recasting of the adage that “an ounce of prevention is worth a pound of cure.” It calls for action to prevent harm when scientific evidence about an environmental hazard is incomplete, but the stakes are high. Both an empirical claim and an ethical claim, it involves four aspects.69 First, when harms are known to increase as a result of particular actions, measures should be taken to prevent that action even if the cause-and-effect relationships are not fully understood. Second, the burden of proof of no harm is shifted onto the entity producing the action—a chemical manufacturer or a factory farm, for example. Third, alternatives to harmful processes are encouraged—ranging from technical fixes such as seaweed-based plastics, to system change such as the circular economy. Finally, the precautionary principle advocates robust public and interdisciplinary communication within decision-making processes. This is meant to deliver the most effective strategies for reducing harm. For planetary health ethics, the precautionary principle is important for three key reasons. First, given that it advocates for action in the face of possible harm and shifts the burden of proof to those engaging in a potentially harmful activity, it greatly reduces the number of people exposed to a harm. Second, the need for alternatives to harmful actions can be linked with the previous call for distributive justice. Considering the contraction and convergence model, we might imagine something analogous to a product such as plastics, with each entity (be it an individual, a business, or a nation) allowed a certain amount of plastic use. Surpassing that limit would incur a fine proportional to the excess, which in turn would go toward funding research in alternatives to plastics. Third, encouraging participation in the decision-making processes offers the opportunity for marginalized voices to be heard, a point that is further explored in the following section on the right to know.

Action Points • Seek to identify products and processes that cause the greatest harm so that those can be acted on first, an important role for planetary health research. • Implement a system of financial incentives to encourage the transition to products and processes, such as green chemistry (see Chapter 14), that produce less harm.

The Right to Know The right to know is the right for people to be told of the risks present in their everyday lives. Rooted in respect for individual autonomy, this principle holds that it is unethical to withhold information from people when doing so either increases the risk of harm to them or hinders their ability to make informed decisions. The right to know is implemented through dialogue between the affected party (an individual or a community) and the entity doing the informing (a professional, a company, a government agency) that

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allows for participatory decision making.70 Examples of the right to know include food labeling and chemical safety sheets. Key to this process of fostering autonomy are five attributes: open minds, encouragement to develop personal perspectives, eagerness for new facts and insights that may change one’s perspective, facilitating the open expression of other people’s perspectives, and developing reasons for interpersonal and environmental forms of care.70 The right to know has several implications for planetary health. First, information must be presented honestly and objectively. Many of the issues in planetary health are layered with ideological beliefs and vested interests; as a result, deceptive, biased “alternative facts” are all too common.71,72 Planetary health workers must seek to cut through such false presentations. This is an ongoing duty; simply debunking misinformation once is insufficient for preventing that same misinformation from continuing to circulate.73 This may involve confronting climate deniers head-on in public debates. It is arguably unethical to fail to engage such people when their rhetoric can hinder climate change mitigation and thus harm people. Second, the duty to communicate risk is a duty both to listen attentively and to communicate through the language and worldview of the affected people. Failure to listen risks misunderstanding the concerns and perspectives of affected people and not responding appropriately. Failure to communicate effectively risks undermining the engagement and participation of affected people, a key goal of the right to know. This last point is highly relevant to communication across cultural, ethnic, ideological, age, gender, and other differences, as well as at their points of intersectionality. Planetary health communicators, even in the face of urgent challenges, may need to temper their advocacy to allow solution-oriented conversations that work effectively across different belief systems and ways of life.74 For example, current conversations about the need for the world to eat less meat must grapple with environmental and cultural realities in the Arctic, where hunting and eating meat is synonymous with both physical and spiritual survival.75 Planetary health communicators need to understand, respect, and integrate the richness of other ways of approaching the world in a participatory manner that enables grassroots solutions across cultures. Such an approach is likely to yield more robust solutions, with better uptake by local communities, and with less damage to religious and cultural traditions. Third, a right to know is also a right to hope. Planetary health insights can be grim and are often presented in a manner that triggers despair. Grim news should not be concealed or sugar-coated (this would violate the duty of honesty and objectivity), but neither should it be presented in ways that crush hope. Those working within planetary health may want to portray the task at hand as a “Great Work,”76 an inspiring call to “carry out the transition from a period of human devastation of the Earth to a period when humans would be present to the planet in a mutually beneficial manner.” This sense of being “present to the planet” is a call to act mindfully in a manner aligned with

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environmental stewardship. Planetary health narratives might propel hope by emphasizing the co-benefits of mitigating planetary damage, inspiring awe and wonder for the world,9 and encouraging people to fight for the survival of beloved natural places.

Action Points • Translate potential risks into multiple languages and cultures so those affected may understand the potential risk on their terms. • Develop an understanding of the reasons for climate denialism and what arguments and counternarratives are effective in neutralizing it and preventing its spread.77 • Seek to debate climate deniers through public forums in a manner that respectfully and productively engages them.

Conclusion Most ethical guidelines, including the five discussed in this chapter, are grounded in fundamental principles such as respect for autonomy and nonmaleficence. Another approach to planetary health ethics might take as its starting point human rights—rights that, in the words of the United Nations, are “inherent to all human beings.” There are strong arguments for considering a healthy environment as necessary for human thriving and therefore as an appropriate focus of human rights.78–81 The Universal Declaration of Human Rights, the major global framework, does not include a right to a healthy environment, but the international community has debated such a right for many decades. The 1972 Stockholm Declaration on the Human Environment declared that “Man has a fundamental right to freedom, equality and adequate conditions of life, in an environment of a quality that permits a life of dignity and well-being, and he bears a solemn responsibility to protect and improve the environment for present and future generations.” More recently, the UN Human Rights Council began considering a formal promulgation of environmental rights—an initiative that was propelled in part, tragically, by abuses and even murders of environmental activists (Figure 17.3). Many jurisdictions have expanded their human rights frameworks to include such a right in their constitutions (as in dozens of countries, from South Africa to Norway),82,83 in case law (as in Europe; see Mijatović 2019),84 or in innovative litigation strategies advanced by civil society. Examples of such litigation include the Urgenda case against the Dutch government85 and Juliana vs. United States,86 both filed in 2015. The Dutch case drew on the rights to life and to home and family life (Articles 2 and 8, respectively, of the European Convention on Human Rights) to assert a government duty to mitigate climate change. Such legal strategies, combined with constitutional provisions, may presage a universally recognized right to a healthy environment—a practical application of planetary health ethics.

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Figure 17.3 Honduran environmental activist and indigenous leader Berta Cáceres (1971–2016), assassinated a year after winning the Goldman Environmental Prize for her protests against the construction of the Agua Zarca Dam. Her killing was not an isolated incident. Murders of environmental activists—who, like Cáceres, fight for environmental human rights—had reached four per week globally by 2017 (Butt N, Lambrick F, Menton M, Renwick A. The supply chain of violence. Nat Sustain. 2019; 2(8):742–747). Such violence has helped propel the cause of environmental human rights. Source: Courtesy of Goldman Environmental Prize

A right to a healthy environment (now and for future generations) represents a substantial broadening of traditional ethical thinking. Planetary health may call for even more ambitious rethinking—accepting new ways of knowing, less bound by rationalism, individualism, and domination, and more grounded in sensory appreciation, solidarity, and reciprocity, and therefore more congenial to ethical commitments. This would involve what French philosopher Bruno Latour has called “learning to be affected.”87 As Miles and Craddock note, learning to be affected is “not just an awareness of connectivity but also an experience of being transformed by connectivity and coexistence.”8 This involves “opening human sensibilities to allow compassion to encompass all life forms.” In this way traditional ethics—framed in the language of rights and duties—might be reenvisioned in terms of human solidarity with the planet, and a sense of reciprocity with the more-than-human world, a solidarity informed by awareness of our evolutionary origins and mindful of the many benefits of contact, in all its forms, with flourishing ecosystems.

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The formative documents of planetary health expressed the need for such a field and described attributes it should have: a social movement, a scientific framework, an attitude toward life, and a philosophy for living that fosters resilience and adaptation. However, they did not describe all the steps needed to create this field. Ethical principles provide agency to individuals and communities, be they human or nonhuman, in identifying problems and crafting solutions. This chapter has discussed five positions to which planetary health can align itself: intergenerational responsibility, more-than-human rights, distributive justice, the precautionary principle, and the right to know. No single position, by itself, is enough. For example, intergenerational responsibility without distributive justice and more-than-human rights risks people being responsible only to their own families and not the families of others, whether the other is or is not human. We hope that the ethical engagement described here will help planetary health professionals and the communities they serve to achieve the Great Work of planetary health: to reach high levels of health for both people and the natural systems on which we depend.

Authors Alex Foster is an MPhil candidate in medical anthropology at the School of Anthropology and Museum Ethnography, University of Oxford, and he holds a first-class degree in geography, also from the University of Oxford. His research interests lie in the development of low-cost, carbon-negative embodied practices that both improve planetary health and challenge cultural conceptions of the human body. Jennifer Cole, PhD is a research fellow in the Geography Department of Royal Holloway, University of London School of Sustainability and the Environment, and public health policy adviser to the Rockefeller Foundation Economic Council on Planetary Health at the Oxford Martin School, University of Oxford. She studied biological anthropology at Cambridge University and holds a PhD in computer science and geography from Royal Holloway. Ivica Petrikova, PhD is a senior lecturer in international relations at Royal Holloway University of London. She is also a co-director of the Centre for Politics in Africa, Asia, Latin America, and the Middle East. Her research focuses predominantly on the questions of what development is and how it can and cannot be attained, examining the effects of both domestic and external development interventions. Andrew Farlow, MPhil is a senior fellow at the Oxford Martin School, Oxford University’s interdisciplinary school for tackling the big challenges of the twenty-first century. He is coordinating the planetary health activities of the Oxford in Berlin initiative, with the

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aim of Oxford, Berlin, and other European researchers working alongside researchers in Africa, India, China, Brazil, and elsewhere in finding solutions that protect the planet and human health and wellbeing. Howard Frumkin, MD, DrPH is professor emeritus of environmental and occupational health sciences, and former dean, at the University of Washington School of Public Health.

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49. Chakrabarty D. The climate of history: four theses. Crit Inq. 2009;35(2):197–222. 50. Shaw D, Carrington M, Chatzidakis A. Ethics and Morality in Consumption: Interdisciplinary Perspectives. New York, NY: Routledge; 2016. 51. Schwartz D. Consuming Choices: Ethics in a Global Consumer Age. 2nd ed. Lanham, MD: Rowan & Littlefield; 2017. 52. Stott R. Contraction and convergence: the best possible solution to the twin problems of climate change and inequity. BMJ. 2012;344:e1765. 53. Baatz C. Climate change and individual duties to reduce GHG emissions. Ethics Policy Environ. 2014;17(1):1–19. 54. Bowman P. Fair shares and decent lives. Ethics Policy Environ. 2014;17:24–26. 55. Lazrus H. Sea change: island communities and climate change. Annu Rev Anthropol. 2012;41(1):285–301. 56.

Pal J, Eltahir E. Future temperature in southwest Asia projected to exceed a threshold for human adaptability. Nat Clim Change. 2016;6:197–200.

57. Leichenko R, Silva JA. Climate change and poverty: vulnerability, impacts, and alleviation strategies. Wiley Interdiscip Rev Clim Change. 2014;5(4):539–556. 58. Crate S, Nuttall M, eds. Anthropology and Climate Change: From Encounters to Actions. Walnut Creek, CA: Left Coast Press; 2009. 59. Diffenbaugh NS, Burke M. Global warming has increased global economic inequality. PNAS. 2019;116(20):9808–9813. 60. McElwee P. From Conservation and development to climate: anthropological engagements with REDD+ in Vietnam. In: Barnes J, Dove M, eds. Climate Cultures: Anthropological Perspectives on Climate Change. New Haven, CT: Yale University Press; 2015. 61. Beymer-Farris B, Bassett T. The REDD menace: resurgent protectionism in Tanzania’s mangrove forests. Glob Environ Change. 2012;22(2):332–341.

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62. Mechler R, Bouwer L, Schinko T, Surminski S, Linnerooth-Bayer J, eds. Loss and Damage from Climate Change: Concepts, Methods and Policy Options. New York, NY: Springer; 2019. 63.

Mechler R, Schinko T. Identifying the policy space for climate loss and damage. Science. 2016;354(6310):290–292.

64. Drydyk J. Development ethics and the “climate migrants.” Ethics Policy Environ. 2013;16(1):43–55. 65. Nawrotzki RJ. Climate migration and moral responsibility. Ethics Policy Environ. 2014;17(1):69–87. 66. Eckersley R. The common but differentiated responsibilities of states to assist and receive “climate refugees.” Eur J Political Theory. 2015;14(4):481–500. 67. Marshall N. Forced environmental migration: ethical considerations for emerging migration policy. Ethics Policy Environ. 2016;19(1):1–18. 68.

Farbotko C, Lazrus H. The first climate refugees? Contesting global narratives of climate change in Tuvalu. Glob Environ Change. 2012;22(2):382–390.

69. Kriebel D, Tickner J, Epstein P, et al. The precautionary principle in environmental science. Environ Health Perspect. 2001;109(9):871–876. 70. Lambert TW, Soskolne C, Bergum V, Howell J, Dossetor JB. Ethical perspectives for public and environmental health: fostering autonomy and the right to know. Environ Health Perspect. 2003;111(2):133–137. 71. Keyes R. The Post-Truth Era: Dishonesty and Deception in Contemporary Life. New York, NY: St. Martin’s Press; 2004. 72. Oreskes N, Conway EM. Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming. London, UK: Bloomsbury; 2010. 73. Thorson E. Belief echoes: the persistent effects of corrected misinformation. Polit Commun. 2016;33(3):460–480. 74. Stengers I. Cosmopolitics (Posthumanities). Vols 9–10. Minneapolis, MN: University of Minnesota Press; 2010. 75. Blaser M. Is another cosmopolitics possible? Cult Anthropol. 2016;31(4):545–570. 76. Berry T. The Great Work: Our Way into the Future. New York, NY: Bell Tower; 1999. 77. Gifford R. The dragons of inaction: psychological barriers that limit climate change mitigation and adaptation. Am Psychol. 2011;66(4):290–302. 78. Shelton D. Human rights, environmental rights, and the right to environment. Stanf J Environ Law. 1991;92(28):103–138. 79. Boyle A. Human rights and the environment: where next? Eur J Int Law. 2012;23(3):613–462. 80. Leib L. Human Rights and the Environment: Philosophical, Theoretical and Legal Perspectives. Leiden, Netherlands: Brill; 2011. 81. May J, Daly E, eds. Human Rights and the Environment: Legality, Indivisibility, Dignity and Geography. Cheltenham, UK: Edward Elgar; 2019. 82. May J, Daly E. Global Environmental Constitutionalism. Cambridge, UK: Cambridge University Press; 2015. 83.

Jeffords C, Gellers G. Constitutionalizing environmental rights: a practical guide. J Hum Rights Pract. 2017;9(1):136–145.

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84. Mijatović D. Living in a clean environment: a neglected human rights concern for all of us. 2019. https://www.coe.int/en/web/commissioner/-/living-in-a-clean-environment-a -neglected-human-rights-concern-for-all-of-us. 85.

Urgenda. The Urgenda case against the Dutch government. 2019. https://www.urgenda .nl/en/themas/climate-case/. Accessed April 2020.

86. Our Children’s Trust. Juliana v. United States. 2019. https://www.ourchildrenstrust.org /juliana-v-us. Accessed April 2020. 87. Latour B. How to talk about the body? The normative dimension of science studies. Body Soc. 2004;10(2–3):205–229.

18 A Bright Future for Planetary Health Samuel Myers and Howard Frumkin

On September 23, 2019, 16-year-old Swedish climate activist Greta Thunberg (Figure 18.1) addressed world leaders who had come together for the UN General Assembly. “This is all wrong,” she told them. “I shouldn’t be up here. I should be back in school on the other side of the ocean. Yet you all come to us young people for hope? How dare you! You have stolen my dreams and my childhood with your empty words. And yet I’m one of the lucky ones. People are suffering. People are dying. Entire ecosystems are collapsing. We are in the beginning of a mass extinction. And all you can talk about is money and fairytales of eternal economic growth. How dare you!” She continued: “You are failing us. But the young people are starting to understand your betrayal. The eyes of all future generations are upon you. And if you choose to fail us, I say we will never forgive you. We will not let you get away with this. Right here, right now is where we draw the line. The world is waking up. And change is coming, whether you like it or not.” And so here we find ourselves at a pivotal moment in human history. After millions of years of biological evolution and thousands of years of social evolution we have, in the blink of an eye, multiplied our numbers and our consumption of resources to the extent that we imperil the natural systems that support us and all living beings. Our wealth, health, education, and opportunities exceed anything we have experienced before, but they have been carried forth on the groaning back of a crumbling biosphere.1 Our current trajectory leads to ecological collapse and the unraveling of our many gains. Now the eyes of all future generations are upon us, and within a few decades we must chart a new course from extinction to renaissance. We are a community forged in urgency.

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Figure 18.1 Sixteen-year-old Swedish climate activist Greta Thunberg. Her sign reads “Schoolstrike for Climate.” In 2019, Thunberg’s climate activism galvanized hundreds of thousands of school children around the world to strike in protest of governments and schools that were doing little to ensure they had a livable future. Source: Photo by Anders Hellberg (Wikimedia), Creative Commons, license CC BY-SA 4.0

In the face of these challenges, hope can seem elusive. Many Earth system trends are grim, the popular and scientific literature is full of apocalyptic scenarios,2,3 and progress to date has been slow. But as Thunberg and so many in her generation are emphasizing, we have a choice. Within our reach is a future that sparkles with promise, in which humanity has never been healthier, better educated, or happier, and in which opportunities are more accessible than ever before to people of every gender, race, ethnicity, and religion. The chapters of this book have presented core elements of a world that we would be proud to bequeath to Greta Thunberg and her generation, and that they might be glad to inherit. In it, the human population has stabilized and then started to decline as a natural

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Box 18.1. Ten Ways to Save the World • Transitioning to renewable energy • Conserving forests • Combating soil degradation • Better water management • Protecting biodiversity • Curbing overfishing and ocean pollution • Building greener cities • Reducing waste and improving recycling • Strengthening reproductive healthcare • Transitioning toward a healthier diet Source: Davey E. Given Half a Chance: Ten Ways to Save the World. London, UK: Unbound Publishing; 2019.

result of the demographic transition. Food is produced much more efficiently, with lower inputs of land, water, agrochemicals, and energy. Energy is produced renewably in a postcombustion world in which CO2 levels are beginning to decline. People are living mostly in cities designed to optimize their health, both physical and mental, encourage social connectedness, and minimize their ecological footprints. With each passing decade there is more room, not less, for the rest of the biosphere. Human wellbeing is on the rise, and we are living in harmony with the natural world. Inventories of these solutions have appeared in many places (Box 18.1). In the following paragraphs we offer a recap.

Getting It Right Population As described in Chapter 3, the impact of human beings on natural systems is a product of the number of people, their consumption patterns, and the technologies they use to produce goods or process wastes. A future population with fewer people will need less energy, less food, and fewer natural resources, and produce less waste, than a larger population living similar lives with similar technologies. Thankfully, the interventions that reduce fertility and population growth are valuable in their own rights. Educating girls, providing economic opportunities for women, and giving couples access to contraception encourage gender equality and women’s rights while reducing maternal and child mortality. They also slow population growth. It is easy to imagine a world in which these interventions are universal, with population stabilizing and then falling over time as couples choose smaller families.

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Food Systems As discussed in Chapters 4 and 5, the global food system is the leading cause of biodiversity loss, land use change, and water scarcity and a major contributor to pollution and climate change. It is also massively inefficient; Chapter 5 discusses a suite of interventions that can reduce food waste and produce food with much lower inputs of land, water, energy, and agrochemicals. Many of these interventions, from innovative technology such as precision agriculture or artificial meat to agroecological practices, are already in full swing and simply require government and industry support to accelerate and expand them. Changing our diets (e.g., by reducing red meat and processed food consumption) is another area, like providing access to contraception, in which doing what is best for the global environment also pays large health dividends. There are major opportunities in the policy realm: Removing perverse subsidies, pricing the health externalities of less healthy foods while providing positive support for healthier foods will drive the transformation to healthier and more sustainable diets. Keeping a keen eye on issues of equity and access as this transformation unfolds is critical. Combining these different types of interventions, it is easy to imagine a world in which the ecological footprint of producing humanity’s food supply is a great deal smaller than today’s, while the health benefits of that supply are greater.

Energy The world we need to deliver to Thunberg’s generation and those that follow is a postcombustion world. As discussed in Chapter 12, the technologies to supply the world with renewable, carbon-free energy exist and are economically competitive with fossil fuels. But the challenge of scaling those technologies and creating the energy infrastructure to deliver renewable energy to all people everywhere is immense. Such a transition will require a massive global mobilization that needs to start immediately. Comparable to other planetary health interventions, there are enormous health co-benefits of such an energy transition in reducing air pollution, which is cutting millions of lives short. As described in Chapter 10, each day lost increases the suffering of the most vulnerable populations as climate change intensifies. Like so many planetary health challenges, this is mostly a challenge of political will, not expertise, and will require a global movement of engaged citizenry demanding urgent action.

Built Environment In the future, we will live mostly in cities. There is enormous promise in designing those cities to optimize our physical and mental health while minimizing our ecological footprints. We will live in buildings constructed of clean, safe, and sustainably produced materials. They will be dramatically more efficient than today’s buildings in their use of energy. They will recycle and reclaim wastewater, generate their own energy, and feature

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vertical and rooftop gardens to keep them cool, produce food, improve mental health, and encourage social connectedness. Our neighborhoods will be designed around walking and cycling instead of the automobile, with mixed-use zoning allowing people to live, work, and recreate in the same areas. They will include parks and greenways, connecting us to nature and each other. Design principles, for both buildings and neighborhoods, will draw from nature, which has been beta-testing solutions for millions of years—socalled biophilic design.4–6 Convenient, inexpensive mass transit will enable people to move about cities easily. And our metropolitan regions will turn solid waste into energy, water, and fertilizer, as discussed in the Chapter 16 example from Santiago de Chile.

Industry and Business Companies of the future will operate very differently from the companies of the past. Both their shareholders and a broad range of stakeholders will hold them accountable for the full life cycle impact of their goods and services on both the environment and human wellbeing. Firms will operate in accordance with the circular economy, keeping products in use, reducing the use of energy and resources, minimizing waste, and directing waste as inputs to other processes.7 Although large firms will continue to function, there will have been considerable relocalization, and many small companies will make and sell goods and services in the communities where their leaders and employees live.8,9 Industrial design will be informed by biomimicry, drawing on the naturally occurring genius to be found in silk, gecko feet, and inchworm locomotion.10,11 Accordingly, as described in Chapter 14, persistent and toxic materials will no longer be produced and released into the environment. The sharing economy will have expanded; people will own fewer goods, from vehicles to power tools,12 reducing the need to consume resources to make things. The private sector will be, as it has always been, a powerful engine for innovation, now addressing rapidly growing demand for sustainably produced products with much smaller ecological footprints, from zero-waste consumer products lines to renewable energy to precision agriculture to more sustainable food technologies.

Economics Alongside these changes in the ways we make and consume goods and services, economic theory will have evolved as well. As described in Chapter 15, the doctrine of perpetual economic growth will give way to a doctrine of perpetual growth of human wellbeing— a form of growth that doesn’t require the constantly increasing, unsustainable use of energy and raw materials. New indicators will be needed to monitor this growth; the gross domestic product, no longer fit for purpose, will give way to metrics of human and environmental wellbeing. Externalities will be internalized; the costs of goods and services will reflect their true cost to society and to the planet, helping to inform sound public policies in areas such as subsidies. Importantly, mechanisms to prevent gross inequities in

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the distribution of opportunity and wealth will be implemented. These may range from time-tested approaches such as reinvigorated labor laws and universal health coverage to more innovative mechanisms such as wealth taxes and a guaranteed basic income.

From Here to There The authors of this book’s many chapters have emphasized consistently that we are at a crossroads. A business-as-usual path commits us more completely to living in the world that Thunberg chillingly described: “People are suffering. People are dying. Entire ecosystems are collapsing.” A different path takes us toward the aspirational world we have described. The contours of that world are already taking shape in front of us; they are within grasp. The question is not, “Can we achieve such a future?” It is “Will we?” As important as the technical elements of the solution outlined above are the cultural elements that will answer this all-important “Will we?” question. “The future does not have to be bleak,” wrote a global group of sustainability researchers and futurists in 2016. “The continuing emergence of new thinking, innovative ways of living, and different means to connect people and nature are vital in overcoming critical local and global challenges that otherwise constrain sustainable Earth stewardship.”13 In theory, we as a species have what it takes to rise to the epic challenges of planetary health: the capacity for evidence-based reasoning and logical analysis, the ability to engage in long-range planning, the capacity for moral judgment, extraordinary talent for innovation, and the ability to feel compassion for each other and for other species.14 Four important elements of the needed transformation will be compelling shared visions that drive hope and optimism, changing the way we generate and share knowledge, deepening the human relationship with the natural world, and building movements for social action to drive needed change.

Shared Vision A part of what motivates people to come together, sacrifice, commit acts of civil disobedience if necessary, and insist on being heard is a shared vision for the future. Aspirational visions are the stories we tell ourselves about our future. They are connected to our stories about who we are, our relationships with each other, and our place in the world. Aspirational visions arise from many sources: the hopes and dreams of young people; the ancient wisdom of Indigenous peoples; organized religions with their ethics of stewardship, justice, and legacy thinking; the imagination of artists and writers; the creations of scientists and engineers; and the inspiration of our best leaders and thinkers. These will all be necessary in the transition to a state of planetary health. No single vision will motivate everybody; people view the world and form their hopes through the lenses of culture, faith, education, family, and friends. But some visions serve better than others. A vision for a planetary health future should be radically different

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Table 18.1. Criteria for Quality Visions of a Sustainable Future Visionary

A desirable, aspirational future state, with elements of surprise, utopian thought, farsightedness, and holistic perspective

Sustainable

Complies with sustainability principles; features radically transformed structures and processes

Systemic

Holistic representation; linkages between vision elements; complex structure

Coherent

Composed of compatible goals, free of irreconcilable contradictions

Plausible

Evidence-based, informed by empirical examples, theoretical models, and pilot projects

Tangible

Composed of clearly articulated and detailed goals

Relevant

Composed of salient goals that focus on people and their roles and responsibilities

Nuanced

Detailed priorities based on differing values (desirability)

Motivational

Inspire and motivate toward the envisioned change

Shared

Convergence, agreement, and support by relevant stakeholders

Source: Wiek A, Iwaniec D. Quality criteria for visions and visioning in sustainability science. Sustain Sci. 2014;9:497–512.

from contemporary realities yet practical. It should be farsighted and system-based. It should inspire. Social science research suggests that aspirational visions for the future are particularly galvanizing when they invoke a close relationship with nature, collective action, and a moral dimension.15 To motivate broad global collective action, a shared vision of the future will need to emphasize equity and social justice. These and other features of a “quality vision” were outlined by sustainability researchers Arnim Wiek and David Iwaniec (Table 18.1). It takes discipline, intellectual rigor, and courage to form and champion such visions. Fortunately, there is no shortage of bold, articulate, creative leaders—and up-and-coming leaders—who are helping to craft visions for a better future.

Science In the future, knowledge will be funded, created, organized, shared, and taught differently than was traditional in universities through the twentieth century. New institutional forms, such as universities organized around problems rather than disciplines, will

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arise. Research will be less “ivory tower”; researchers will routinely collaborate with communities, policymakers, the private sector, and other stakeholders in framing and carrying out their research.16,17 Academic disciplines that jealously guard their boundaries will give way to transdisciplinary research and teaching organized around solving the world’s great problems.18,19 Knowledge will be freely available to all who need it to solve pressing global problems.20,21 In the academic world, teachers and researchers will no longer be evaluated based on traditional metrics, such as number of publications, but based on impact in solving real-world problems, resulting in a natural emphasis on transdisciplinarity.22,23 The academic and research enterprise will in these ways advance the knowledge needed to ensure planetary health.

Human Bonds with the Natural World In the introductory chapter we asked whether beneath the ecological crisis we are experiencing, and the public health crisis that it threatens, we might also be contending with a spiritual crisis. Achieving planetary health may require addressing this spiritual dimension as well. It may need to reassert what so many people feel: a spiritual connection to the natural world. Cultures and traditions over time and across the globe embrace reverence for the natural world. Indeed, who can observe a flourishing coral reef, an oldgrowth forest, or the stillness of a desert red rock canyon without feeling the tug of awe that lifts one out of oneself? Many organized religions are explicit about this bond.24,25 “We are called—indeed, we are obliged—to embrace our role to preserve the earth as a gift and resource offered to humanity by a loving Creator,” wrote Christian Orthodox Patriarch Bartholomew.26 Pope Francis, in his famous encyclical Laudato Sí—a moving tribute to ecological principles—wrote that creation “can only be understood as a gift from the outstretched hand of the Father of all, and as a reality illuminated by the love which calls us together into universal communion.”27 Evangelicals refer to “creation care,”28 Jews to tikkun olam (healing the earth).29 The 2015 Islamic Declaration on Climate Change affirms that “we are but a minuscule part of the divine order” with “no right to abuse the creation or impair it,” and it calls on people “to tackle habits, mindsets, and the root causes of climate change, environmental degradation, and the loss of biodiversity . . . following the example of the Prophet Muhammad.” An important step on the path to planetary health may be reasserting the authority of our reverence and awe for nature, demanding that our collective actions be consistent with taking care of life on Earth. In this view, it is a profound moral failure to preside over the extinction of so many other species or to treat our atmosphere and oceans as gigantic rubbish bins.

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Movement Building and Social Action Moving to a healthy, sustainable, and equitable world “can be expected to involve fundamental changes in human values, assumptions, cultures, worldviews, and power relations . . . that influence societal norms and institutions governing behaviour.”13 This far-reaching set of changes has been called the “Great Transition.”30,31 It will not be an easy transition. Existing power relationships, habits, expectations, and technologies need overhaul. As the great abolitionist Frederick Douglass wrote, “Power concedes nothing without a demand. It never did and it never will.” The “demand” of which Douglass wrote can now be heard, more emphatically every day, in social movements arising around the world—of young people demanding a secure future, of Indigenous people demanding land rights, of small island nations demanding recognition of the perils imposed on them, of city dwellers demanding clean air to breathe, of disenfranchised people demanding social and environmental justice. The Great Transition toward planetary health will be achieved because it has been demanded by people across the world, coming together in collective action, holding their governments and industries accountable, and refusing to settle for the destruction of the planet. Achieving planetary health—protecting ourselves by protecting nature—will require many things: aspirational shared visions of the world that can be; a robust science base that enlightens us about the complexities of our biosphere; profound changes in social and economic arrangements, propelled by determined activism; and a renewed consciousness of our connections to the natural world. Innumerable voices will contribute to these changes, driving the mandates to construct our cities differently, configure our energy systems differently, grow our food differently, and produce and consume products differently—to care for life on Earth, as it takes care of us. Thunberg reminds us that “the eyes of all future generations are upon you.” We know much of what we need to do. We need to get on with it, to drive the Great Transition toward planetary health.

Authors Samuel Myers, MD, MPH is a principal research scientist at the Harvard T.H. Chan School of Public Health and director of the Planetary Health Alliance. Howard Frumkin, MD, DrPH is professor emeritus of environmental and occupational health sciences, and former dean, at the University of Washington School of Public Health.

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Afterword: Coronavirus and planetary health

Howard Frumkin and Samuel Myers During the two years of this book’s gestation, our planet was ringing warning bells with increasing urgency. Intense hurricanes devastated the Caribbean; wildfires raged in California and Australia, Siberia and the Amazon; droughts and civil strife brought famine in the Sahel; and the worst locust outbreak in 70 years destroyed crops in East Africa. Each of these planetary signals warned us that humanity is engaged in a fundamentally risky relationship with our natural systems.

A novel coronavirus But perhaps the loudest warning bell tolled on the eve of the book’s publication, when a novel coronavirus erupted in Wuhan, the capital of China’s Hubei province (Figure A.1). The first victim was probably infected in that city’s Huanan Seafood Wholesale Market in November, 2019. By mid-December, 27 cases had been identified in China, and by the last day of the year, there were 381. Within three weeks, Korea, Thailand, and Japan had reported cases of the new infection, and a week later there were cases in Europe and North America. The novel coronavirus was quickly named—SARS-CoV-2—and sequenced. By the end of January, 11,950 cases had been reported in 21 countries. By the end of February the new disease had been officially named Covid-19, and the case count had reached 84,615. A month later still, at the end of March, the count was ten times higher: 859,798. By April 22—poignantly, the 50th Earth Day—more than 2.5 million cases had been diagnosed, approximately 180,000 people had died, and the numbers were rising. People were isolating themselves around the world. The global economy was in tatters. And the full impact of the disease had not even begun to manifest in the crowded cities of the Global

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Figure A.1 An image of a coronavirus as seen through electron microscopy, showing the surface studded with glycoproteins that give it the appearance of a crown, hence its name. Source: Centers for Disease Control and Prevention, Public Health Image Library. Image 23311. https://phil.cdc.gov/Details .aspx?pid=23312

South, from Delhi to Maputo, from Cairo to São Paulo, or in failed states from Venezuela to Libya. As we write this epilogue, in late April, 2020, the ultimate trajectory of Covid-19 cannot be predicted. But a planetary health lens helps to contextualize the pandemic within the broader context of many themes we have explored in this book. The “spillover” of infectious diseases from animals to humans is well established, as described in Chapter 6. Bubonic plague—cause of the 14th-century Black Death, which wiped out nearly a quarter of the global human population—is caused by the bacteria Yersinia pestis, which is carried by rodents and transmitted to humans by fleas. Ebola virus was recognized in 1976, in outbreaks in what are now Democratic Republic of Congo and South Sudan; the natural reservoir may be bats, and several primate species are intermediate hosts. Nipah virus arose in Malaysia in 1998, probably from fruit bats, and was transmitted to humans through pigs. HIV originated with simian immunodeficiency virus in chimpanzees in Central Africa. Influenza viruses have come from birds (as in the 1918 flu) and from pigs (as in the 2009 H1N1 outbreak). Previous coronaviruses moved from bats to humans via intermediate mammalian hosts—civet cats in the case of SARS (in 2002) and camels in the case of MERS (in 2012). SARS-CoV-2 probably originated in bats, and jumped to humans through an intermediate host, perhaps pangolins. In fact, the majority of emerging infectious diseases are zoonotic infections from wildlife (Jones et al., 2008).

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In each of these cases, many factors helped the pathogen jump from animals to humans and then to disseminate. Environmental conditions, from changing rainfall patterns to forest fragmentation and clearing, often played a role. Human incursions into animal habitat for agriculture, logging, mining, and bushmeat hunting are common triggers. Global trade and travel, and crowded cities, contribute. In China, where SARS-CoV-2 emerged, and in other parts of Asia and Africa, there is a robust trade in wildlife for food, with bats and rats, porcupines and pangolins, civets, scorpions, and squirrels, turtles and a variety of birds, among other animals, crammed in close quarters in crowded markets. “We made the coronavirus epidemic,” wrote David Quammen, the author of Spillover: Animal Infections and the Next Human Pandemic. “We invade tropical forests and other wild landscapes, which harbor so many species of animals and plants—and within those creatures, so many unknown viruses. We cut the trees; we kill the animals or cage them and send them to markets. We disrupt ecosystems, and we shake viruses loose from their natural hosts. When that happens, they need a new host. Often, we are it” (Quammen, 2020). But it isn’t just invading wild places that primes the pump for infections. It’s also the way we produce our food. Writing of the novel coronavirus, MIT professor Kate Brown observed that “The pandemic is not a natural disaster.” While early agriculture enabled populations to grow and cities to form and flourish, Professor Brown wrote, “crops and livestock, once they were concentrated in one place and cultivated in monocultures, became vulnerable to disease. As cities and farm operations grew, people and animals crowded closer together. The result was a new epidemiological order, in which zoonotic diseases—ones that could jump from animal to human—thrived” (Brown, 2020). Denser human populations also began producing monocultures of crops which simplified farming but allowed a single pathogen to devastate entire harvests. History is littered with the catastrophic results, affecting both people and the crops on which we depend: the potato blight that killed a million Irish people in the mid-19th century (Ireland’s population has still not recovered); the epidemic of grape phylloxera that almost wiped out the French wine industry in the late 19th century; Panama disease which eradicated the beloved Gros Michel banana in the mid-20th century; wheat rust and stem rust which have caused waves of famine for centuries and are currently on the rise in Africa; coffee rust which is now devastating the Latin American coffee industry and helping drive migration to the United States. The human enterprise has intensified greatly during the Anthropocene, and especially during the last century. With it, new and re-emerging infectious diseases have appeared with increasing frequency.

Covid-19 as a planetary health problem The outbreak of Covid-19 illustrates many of the themes emphasized throughout this book. In fact, Covid-19 is a quintessential planetary health problem.

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Complex systems: The first law of ecology, as Barry Commoner wrote in 1971, is that everything is connected to everything else. The response to Covid-19 is illustrative. Planners need to anticipate the rate of disease spread—a function of how frequently people encounter each other, the extent of protective equipment use, and other factors. They need to anticipate the resulting disease burden—a function of the coronavirus virulence, a population’s age profile and underlying health, and the effectiveness of medications and vaccines. They need to anticipate the capacity of the health care system—a function of existing facilities, supply chains, and staffing (including impacts on staffing of the disease itself). In doing these things, they need to anticipate second- and third-order effects and feedback loops. For example, if schools close, doctors and nurses have to mind their children—so health care system capacity declines. Such complexity is the rule, not the exception, in planetary health challenges. Geographic reach: In a globalized world, system connections can cover vast distances. Just as the virus travelled far, so do people and so does global trade; the shortage of face masks and diagnostic reagents in the United States had everything to do with supply chains that stretch back to China. It may seem far-fetched that a chance event in an unknown market in Wuhan could result in cancellation of the Boston Marathon, or the death of folk singer John Prine in Nashville, or the bankruptcy of Whiting Petroleum in Denver—much less the police clubbing of pedestrians in Delhi or the shooting of a 13-year-old in Nairobi. But these far-flung impacts illustrate the level of global connectedness that characterize the planet’s human and natural systems. Surprises: Complex systems have both a tendency to maintain stability and a capacity for sudden shifts. While infectious disease experts had long warned of the possibility of a pandemic like Covid-19, the emergence of the virus, and its extraordinarily rapid global spread, were sudden and shocking—a “predictable surprise.” The triggering event may have been a shift in the viral genome toward a configuration both contagious and deadly. Other large-scale events—some sudden, such as cyclones and floods, others gradual, such as pollinator loss and crop collapses—also exemplify this potential for “business as usual” to be upended, with far-reaching impacts on human health and well-being. Equity: A disaster such as the Covid-19 outbreak (or a typhoon, or a heat wave) typically occurs against a backdrop of ongoing disasters: income inequality, structural racism, dysfunctional government. As Covid-19 swept the United States, a pattern of stark racial disparities emerged. In many states and cities, African-Americans were over-represented two- to three-fold among Covid-19 cases and deaths relative to their proportion in the population. Among the explanations are higher underlying rates of diseases that could increase vulnerability, such as hypertension and diabetes—diseases that are associated with the stress of racism. Similarly, African-Americans are disproportionately employed

Afterword  491

as public transit and delivery drivers, personal care workers, hospital cleaning staff, and other jobs that pose exposure risk, may provide inadequate personal protective equipment, and do not permit isolating while working from home. Members of racial and ethnic minorities are disproportionately likely to be poor, and therefore more likely to live in crowded quarters that facilitate disease transmission. African-Americans are substantially more likely than Whites to lack health insurance. Four in ten U.S. households do not have the cash on hand to cope with an unexpected $400 expense such as a car repair or replacing a broken appliance, and African-American households are two to three times more likely than White households to be in this low-cash predicament (Federal Reserve, 2019). The lack of cash reserves hits hard when a pandemic puts a stop to paychecks. Disasters lay bare these disparities, and remind us that long-term solutions that achieve health, well-being, and sustainability must incorporate social justice as well. The human relationship with nature: The emergence of Covid-19 reflects a rupture of the human relationship with the natural world. While the global trade in bushmeat serves important nutritional roles in some settings, it threatens hundreds of species with extinction (Ripple et al., 2016), and it threatens humanity with serious infections (Johnson et al., 2020). Moreover, the casual cruelty that underlies this practice (Figure A.2)

Figure A.2 Bush meat on sale at the weekly market of Yangambi, DRC. The main animals sold are warthogs, monkeys and Gambia rats. Photograph by Axel Fassio. Source: CIFOR (Center for International Forestry Research)

492  Afterword

may numb people to the beauty and existence value of the more-than-human world. It is also inconsistent with the notion that we humans exist in relation to the other beings on our planet and have a moral obligation to treat them with compassion and dignity— a spiritual tenet of many of the world’s religions and indigenous traditions (Tucker and Grim, 2020). Ironically, as social distancing and stay-at-home mandates were increasingly imposed across the United States, people flocked to local and national parks, turning to nature for relief and solace from the pandemic’s impact. Park managers at first kept parks open, recognizing the essential service they provided, but soon closed them because the volume of visitors made social distancing impossible to maintain (Figure E.3). Covid-19 reminds us, yet again, that we need a balanced relationship with the natural world, substituting stewardship for domination, reverence for arrogance, coexistence for conquest. Building resilience, preparing for disasters: Covid-19 revealed the extent to which nations had heeded early warnings and prepared. Nations such as South Korea and Taiwan, which had recently confronted SARS, had relatively strong responses. The U.S., in contrast, demonstrated what can only be characterized as reckless insouciance.

Figure A.3 A park closed in Clinton Township, New Jersey, in April, 2020, due to Covid-19. Just as the benefits of nature contact are more needed than ever, access to parks has been restricted. Source: Ed Murray / NJ Advance Media. Used with permission.

Afterword  493

Shortcomings that rapidly emerged in the U.S. included a threadbare public health infrastructure, tenuous supply chains for essential supplies and equipment such as ventilators and protective masks, absence of central coordination of the pandemic response, absence of scalable testing or vaccine manufacturing capacity, and absence of adequate social safety nets to protect people who lost jobs. At a time when disasters are becoming ever more common, building resilience, from the community level to the national level, is essential (National Research Council, 2010). Heeding science: While science by no means provides all the answers to civilizational challenges, it provides indispensable guidance. Disregarding, obfuscating, and even bashing science have become normative among some political leaders, right-wing media figures, and internet chatters (Michaels, 2020). This has greatly hindered sensible decision-making regarding climate change, ecosystem protection, pollution control, and other planetary health challenges. Perhaps not surprisingly, it arose in the context of Covid-19, when misinformation rapidly proliferated on social media (Rutschman, 2020), when the U.S. president foolishly recommended untested and even dangerous treatments for the disease, and when state governors moved early to re-open commerce, all against medical and public health advice. It is essential to restore public faith in science, to combat anti-scientific rhetoric, and to integrate science into public health and environmental policy-making (Oreskes, 2019.) Government as a force for good…or not: The coronavirus outbreak is emblematic of challenges that demand large-scale collective solutions. In every country, the response has been led by government, in coordination with civil society, the private sector, academia, and others. National governments, in turn, have coordinated some of their responses through multilateral organizations such as the World Health Organization. When well-managed, this is a path—indeed, the only path—to solving massive collective action problems, not only a pandemic but also climate change, overfishing, ozone depletion, and others. Key contributors to success include governments with ample financial, human, and technical resources, transparent and competent governance, clear accountability, effective communication with the public, and public faith and trust in government. On the other hand, disasters can result in “elite panic” when those in power perceive a threat to their positions (Clarke and Chess, 2008). The coronavirus pandemic response has featured a consolidation of autocratic rule in nations as diverse as Hungary, Brazil, and the Philippines. In the U.S. we have seen audacious restrictions on abortion rights, immigration, environmental regulation, and government oversight, accompanied by equally audacious lifelines for the oil and gas industry, extending the Trump administration’s extreme agenda. The pandemic, like any planetary crisis, vividly illustrates the need for effective, accountable government.

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The basis for hope: But even as the world struggles with the pandemic, there is ample reason for hope. Even in the face of enormous disruption and suffering, the pandemic response improved life in some ways. In cities around the world, the air got cleaner, noise levels diminished, and streets no longer clogged with traffic were allocated to pedestrians and cyclists—glimpses of how a post-carbon future might look (Roberts, 2020). Volunteerism blossomed in cities and towns everywhere, as people demonstrated the kindness and solidarity that often emerge during disasters (Solnit, 2009). Business meetings, classroom teaching, and family visits took place virtually instead of in-person, reducing the associated carbon footprints. Countless articles and social media posts raised probing questions about the human relationship with the natural world, and how to repair it (Goodall, 2020). The novelist Charles Yu, writing in The Atlantic, argued that a “return to normal” after the pandemic should not be the goal, because the pre-pandemic “normal” was built on fictions: “The grand, shared illusion that we are separate from nature. That life on Earth is generally stable, not precarious. That, despite what we know from the historical and geological and biological record, human civilization—thanks to advancements in science and medicine and social and governmental structures—exists inside a bubble, protected from the kind of cataclysmic event we are currently experiencing.” Coronavirus may trigger the rethinking, and help usher in the far-reaching transformation, that planetary health demands. Perhaps more than anything, the pandemic response proved that massive, rapid change, requiring action by governments, private firms, civil society, and families, is possible. A pandemic is not the way anybody would wish to prove that point, but knowing that massive change is possible gives great hope for a brighter future for planetary health. In response to microscopic mutations in a sequence of RNA, the world just ground to a halt. As we turn our minds to next steps, this moment of pause and reflection must lead us down a new path. Around the world, our taxes will be spent on trillions of dollars of stimulus packages to reboot the global economy, and our goal must be not to prop up our old ways of living on Earth but to stimulate the Great Transition to a new relationship with the natural world. Let us turn this moment of darkness and pain into an opportunity for renaissance and regeneration.

References Brown K. The pandemic is not a natural disaster. New Yorker, April 13 2020. https://www .newyorker.com/culture/annals-of-inquiry/the-pandemic-is-not-a-natural-disaster Clarke L, Chess C. Elites and Panic: More to Fear than Fear Itself. Social Forces. 2008;87(2):993-1014. Commoner B. The Closing Circle: Nature, Man, and Technology. New York: Knopf, 1971. Federal Reserve Board. Report on the Economic Well-Being of U.S. Households in 2018. Washington: Board of Governors of the Federal Reserve System, 2019. https://www .federalreserve.gov/publications/report-economic-well-being-us-households.htm

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Goodall J. COVID-19 should make us rethink our destructive relationship with the natural world. Slate, 6 April 2020. https://slate.com/technology/2020/04/jane-goodall -coronavirus-species.html Jones KE, Patel NG, Levy MA, Storeygard A, Balk D, Gittleman JL, et al. Global trends in emerging infectious diseases. Nature. 2008;451(7181):990-3. Michaels D. The Triumph of Doubt: Dark Money and the Science of Deception. Oxford and New York: Oxford University Press; 2020. National Research Council. Disaster Resilience: A National Imperative. Washington, DC: The National Academies Press, 2012. https://doi.org/10.17226/13457. Oreskes N. Why Trust Science? Princeton: Princeton University Press; 2019. Quammen D. We made the coronavirus epidemic. New York Times, 28 January 2020. https://www.nytimes.com/2020/01/28/opinion/coronavirus-china.html. Ripple WJ, Abernethy K, Betts MG, Chapron G, Dirzo R, Galetti M, et al. Bushmeat hunting and extinction risk to the world’s mammals. Royal Society Open Science. 2016;3(10):160498. Roberts D. How to make a city livable during lockdown. Vox 13 April 2020. https://www. vox.com/cities-and-urbanism/2020/4/13/21218759/coronavirus-cities-lockdown -covid-19-brent-toderian. Rutschman AS. Mapping misinformation In the coronavirus outbreak: Health Affairs Blog; 10 March 2020 [Available: https://www.healthaffairs.org/do/10.1377/hblog20200309 .826956/full/]. Solnit R. A Paradise Built in Hell: The Extraordinary Communities that Arise in Disasters. London and New York: Penguin, 2009. Tucker ME, Grim J. The Crisis of Planetary Health: Reflections from the World Religions. April 17, 2020. Berkley Center for Religion, Peace, and World Affairs, Berkley Forum. Available: https://berkleycenter.georgetown.edu/responses/the-crisis-of-planetary-health -reflections-from-the-world-religions. Accessed 24 April, 2020. Yu C. The pre-pandemic universe was the fiction. The Atlantic, 15 April 2020. https:// www.theatlantic.com/culture/archive/2020/04/charles-yu-science-fiction-reality -life-pandemic/609985/

INDEX Note: page numbers followed by “b,” “f,” “t,” or “n” refer to boxes, figures, tables, or notes, respectively.

abortion, 58b activism, 230–31, 236–37, 237f Adjusted Net Savings, 398 agriculture. See also food systems area under (1800 and 2016), 388t climate change and, 125, 132, 174–75, 251 crop yields, 175 diversity loss, 131 drip irrigation systems, 128–29 fertilizers, 75–79, 76f, 116, 155–58 freezing the footprint of, 127 genetic techniques, 129 greenhouse gas emissions from, 116 hydroponics, aeroponics, and vertical farming, 129, 130f intensification of, 84, 127 intercropping, cover crops, crop rotation, and pollinator-friendly practices, 131 land use change and, 81, 82–83 nutritional value of crops, 175 precision, 127–28, 128f, 132 regenerative practices, 89 soil degradation and, 86, 118 tillage and no-till agriculture, 86, 131–32

trends in cereal yields by world region, 119f urban, 341–42 agroecology, 131–32 agroforestry, 132 Aguas Andinas, 445 air pollution. See also carbon dioxide (CO2) emissions; fossil fuel combustion about, 98–99 cities and, 171, 327 climate change and, 249 food production and, 125 fossil fuels and outdoor pollution, 98, 292–93, 296–97 household air pollution (HAP), 289–92, 293f, 313 mental health and, 226 noncommunicable disease and, 167–69 ozone, 168, 249 urban, 171 allergies, 250, 250f aniline dyes, 366 Anopheles mosquitoes, 146, 147, 153, 154 aquaculture, 129–31 arable land, 85–89, 118, 125, 216 Arctic marine mammals, 364–65 Aristotle, 261–62, 265, 458, 459

497

498  Index

artificial intelligence (AI), 440 asbestos, 366 asset and vulnerability analysis, 237 attention restoration theory, 229 Australian indigenous homelands, 270–71 automobile dependency, 171–72 Bangladesh, 59–61b, 206, 251–52, 253, 461, 463 Bartholomew, Patriarch, 482 battery technology, 312 beef production, industrial, 446 behavioral economics, 405 benzene, 366 Beyond Meat, 135, 136, 445–47 Bhutan, 263–64 bicycle use, promotion of, 338–39 biodiversity loss, 94–97, 149–52, 177. See also species richness bioethics, 453. See also ethics biofactories, 445 biofuels, 310–11 biogeochemical cycles, 75–79, 155–58 biomagnification and bioconcentration, 360 biomass burning, 289–92, 293f, 313 biomes, distribution of, 79, 80f biomimicry, 479 BirthStrike movement, 231, 231f boundaries, planetary, 29, 389, 390f, 432–33, 441 Boyden, Stephen V., 24–25, 26, 29 Brown, Kate, 489 Buddha, 261–62 bushmeat, 489,491 business Aguas Andinas biofactories case study, 445 Beyond Meat case study, 445–47 blueprint for planetary health business, 440–41 business model categories, 433–34 dependencies and, 435, 437–39 externalities, internalization of, 434–36, 437f future prospects, 479 Kering EP&L case study, 441–45, 442–44f

new forms of, 439–40 planetary health business, 432–34 resistance, 447 bus rapid transit (BRT), 337–38, 340 cancers. See also disease, noncommunicable chemotherapeutic agents, 359 climate change and, 170 fossil fuels and, 301, 302b, 303b nuclear power and, 301, 306 POPs and, 176, 364–65 toxic chemicals and, 366, 372b Canmore Declaration, 455 cap and trade, 431b, 461 Cape Town, South Africa, 330–31 carbon capture and sequestration (CCS), 310–11 carbon dioxide (CO2) emissions. See also climate change; greenhouse gases coal and, 297 by country, 460f decarbonization, adaptation, and economic development, 75 food production, impacts of atmospheric CO2 on, 121, 122–24b, 126, 175 historical (1800, 1900, and 2016), 388t life cycle by source, 298f per capita emissions, 43–44 petroleum and, 297–99 variance by nation, per capita, 43–44, 43f carbon intensity, 297, 298f carbon monoxide, 291 carbon tax, 430 carrying capacity, 21, 387 Carson, Rachel, 20, 24, 25f, 26 Case studies (Planetary Health Case Studies: An Anthology of Solutions) 8, 56, 84, 135, 158, 175, 445 Central American migration, 193 Chagas disease, 151–52 chemicals, toxic Arctic marine mammals and, 364–65 biomagnification, bioconcentration, and intensification, 360 bird impacts, 363

Index 499

chemical manufacturing, 100–101, 359–60 children and, 367–68 coral reefs and, 362 dose-response relationships, 361–62 endocrine disrupters, 176, 361, 368, 372b, 378 food quality and, 252 governance and coherent policy, absence of, 371, 372–73b green chemistry, 378–82, 380b, 381f historical origins and early warnings ignored, 368–69 insect impacts, 363 lakes and, 77, 363, 364f low-dose toxicity, 361–62, 377–78 metals contamination, 176–77 mixtures, 360–61 nitrogen cycle and, 75–79, 365 persistent organic pollutants (POPs), 176, 364–65 testing and policy, 372–73b, 376–78 toxicological data, absence of, 373–75, 374f unconventional oil and gas development and, 303b worker and community impacts, 365–67 Chesapeake Bay, 193 children air pollution and, 168 BirthStrike movement, 231, 231f chemical exposures and, 367–68 developmental neurotoxicants in, 372b, 374 electronic waste and, 367 intergenerational responsibility and, 457 iron deficiency in, 123b leukemia in, 306 nature, exposure to, 229 prosocial behavior and, 271–72 PTSD in, 235 in refugee camps, 209–11b vulnerability of, 173, 234–35, 246, 333, 340, 367–68 China, 48, 155, 176–77, 226, 291, 296 chlorofluorocarbons (CFCs), 369, 373 circular economy movement, 46, 439

civil conflict. See conflict civil society, 429–30 Clean Development Mechanism, 427 climate change. See also carbon dioxide (CO2) emissions; greenhouse gases; sea-level rise about, 245–46 adaptation, 236 agriculture and, 125, 132, 174–75, 251–52 air quality effects, 249 allergies and, 250, 250f cities and, 327, 329–30 civil conflict and, 252–53 co-benefits of addressing, 236 conflict ant, 252-53 denial of, 235-36 displacement due to, 149, 190–93, 195–201, 252 distributive justice and, 459–63 ethics and, 454–55 fisheries and, 118 food production and nutrition and, 120, 125–26, 251–52 fossil fuels and, 297–301, 313–14 health outcomes, pathways to, 246, 247f human displacement and, 149 impacts, 73 infectious disease and, 144–49, 145f, 148f, 250–51 mental health and, 232, 236, 253 migration and, 190–93, 195-201, 252 mitigation and adaptation, 73–75, 127, 236, 461–62 mortality by country, 460f national security and, 204–05 nitrogen cycle and, 78–79 noncommunicable disease and, 169–70 nutrition and, 251–52 pollinators and, 121 principles linking health and, 253–54 severe weather events and disasters, 169, 248–49 surprises from, 253 Tangier Islands (Chesapeake Bay) and, 193 temperature, global average, 72–73, 72f

500  Index

temperature-related effects, 246–48, 248f tipping points, 73, 74f UN Framework Convention on Climate Change, 427, 428–29 views of, 233f Club of Rome, 23, 28 coal, 293, 296, 297, 300, 300f coal workers’ pneumoconiosis (black lung), 300 Commoner, Barry, 21–22 common pool resources, 274–75, 409, 425, 454 community initiatives, 236–37 concentrated animal feeding operations (CAFOs), 134 conflict ancestral Pueblo peoples and, 190 causal links between migration and, 206–7 climate change and, 202–205, 252–53 cooperation instead of, 206 Darfur, 191–92, 205 glossary, 203b health implications, 207–8 migration, links to, 206–07 number of, 201, 202f primary vs. secondary factors, 193 resource scarcity and, 202–6 slow- vs. rapid-onset, 193 solutions, 212–13 conservation of ecosystems, 31, 56, 62-64f, 83, 270–71, 454, 456 of energy, 47f, 312–13 of forests, 154, 460 of soil, 89, 132 of water, 92, 94 consumption cumulative, 37–38 GDP decoupled from throughput, 46 growth in, 40–41, 42f and happiness, 45, 52–53, 261, 268, 398–99 I = PAT equation, 37, 52 metrics on growth of, 5, 5f policy considerations, 49–51 Roseto, PA, immigrant/Americanization study, 45

strategies, 51–53 urban, 328–29 variance by country, 41–46, 43f contraception, 57–58b, 64 contract and converge, 461 Convention on Biological Diversity (CBD), 95, 429 Convention on Long-Range Transboundary Air Pollution, 427 Copenhagen, 334–36 coral reefs, 73, 330, 362 coronavirus, 487–90, 493–94 cost-benefit analysis (CBA), 371, 403 Covid-19, xiii, 487–94 crowding, 173 Curitiba, Brazil, 337f, 340, 342 dams, hydroelectric, 81, 308–09 Darfur conflict, 191–92, 205 DDT, 146, 369 dead-end hosts, 143b deep ecology, 9 Deepwater Horizon, 301 deforestation, tropical, 83, 153–54, 175, 291–92 denial of environmental impacts, 235–36 density, in urban form, 332, 334, 340 depreciation, 395 development, economic colonialism and, 31 dark side of, 31 decarbonization and economic development, 75 disease and, 159, 165 ecological economics and, 404 energy and, 289, 313 fertility, family planning, and, 54, 56, 60–61b, 64–65 human development improvement measures, 3, 4f Human Development Index (UN), 265, 398 Millennium Development Goals (MDGs), 288 PHE projects and, 62–63b poverty and economic development, 45, 50 poverty eradication and sustainable development, 463

Index 501

Sustainable Development Goals (SDGs), 178f, 288, 398, 429, 429f developmental neurotoxicants, 372b, 374 development economics, 405–6, 423 diarrheal disease, 251 diet. See food systems disability-adjusted life years (DALYs), 420–21, 421f disasters and acute events. See also fire; flooding Bhopal chemical disaster, India, 366 children and, 235 cities and, 329–30 climate change and, 73–74, 169, 245–46, 248–49 dam failures, 309 Irish potato famine, 190 mental health and, 212, 222–24, 253 migration, displacement, and, 194, 197, 198b, 208, 213 nuclear accidents, 307 Oklahoma Dust Bowl, 190–91 poverty and, 200 discounting, 418–20, 418t disease, infectious biodiversity loss and, 149–52 categories of, 143t cities and, 333 climate change and, 144–49, 145f, 148f, 250–51 emerging diseases and zoonotic pathogens, 141–44 foodborne and waterborne diseases, 251 hydroelectric dams and, 309 land use changes and, 152–55 methods, 144 migration and, 208–11 policy and management implications, 158–59 pollution, altered biogeochemical cycles, and, 155–58 pollution, biogeochemical cycle changes, and, 155–58 terms and definitions, 142–43b disease, noncommunicable (NCDs) about, 165–66, 166f biodiversity loss and, 177 cancer risk, 170 cardiovascular disease, 169

climate change and, 169–70 diabetes, 212 diet and, 134 energy, air pollution, and, 167–69 food, nutrition, agriculture, and, 174–77 integrated exposure–response (IER) curves, 293f kidney disease, 170 leukemia, 306 metabolic disorders, 114, 115b migration and, 212 Non-Communicable Disease Alliance, 430 Sustainable Development Goals and, 178f toxic chemicals and, 365–66 urbanization and, 170–74 displacement. See migration and displacement, human distributive justice, 459–63 doughnut economic model of safe and just operating space for humanity, 399–400, 399f drip irrigation systems, 128–29 drought. See water scarcity and drought Dubos, René, 23–24, 23f, 26 Earth Overshoot Day, 387 EAT-Lancet Commission on Healthy Diets from Sustainable Food Systems, 133, 134 ecoanxiety, 230 ecological economics, 404, 410 ecological grief, 230 economic development. See development, economic economics. See also business aggregate healthy life expectancy and wellbeing as outcomes, 401–2 biosphere size vs., 387–89, 388t circular economy movement, 46, 439 cooperation, coordination, and incentives, 427 discounting, 418–20, 418t economic theory vs. economic dogma, 390–91 ecosystem services and, 410, 411f externalities and, 391, 395, 396, 408–9, 408f

502  Index

GDP alternatives, 397–400 GDP as deficient measure, 393–97 health, measuring and valuing, 420–21, 421f invisible hand (Adam Smith), 391 multicapital framework and natural capital, 410–13, 412f, 440–41 public goods, 409 supply, demand, and equilibrium, 407–8, 407f three-factor and two-factor models (land, labor, and capital), 392–93, 392f valuation, 413–20 welfare economics and supply and demand, 406–8 wellbeing, measuring and valuing, 421–22 economics, types of behavioral, 405 classical and neoclassical, 392–93, 406 development, 405–6 ecological, 404, 410 environmental, 403 health, 405 natural resource, 404 normative, 403 positive, 403 welfare, 406–8 wellbeing, 405 ecopsychology, 229 ecosphere, 379–82, 381f ecosystem services agriculture and, 159 biodiversity and, 95 business dependencies and, 437–38 categories of, 79n, 410 chemical pollution and, 363 cost-based valuation and, 416 cultural, 271 defined, 9 externalities and, 436 natural capital and, 412 regulation and, 435 subsidies and, 430 tropical forest conservation and, 154 wellbeing and, 410, 411f

ecotoxicology, 361–65, 364f efficiency buildings, 347 economic, 51, 405, 408–09, 441 energy, 47f, 288, 312–13, 328-29, 334, 340, 380b food systems, 126–33, 342, 477 resource use, 79, 404, 439 toxicity testing, 377 transportation, 336–38, 339–40 water use, 92–94, 93f Ehrlich, Paul, 21, 26, 37 El Salvador, 206, 212 electrical grid, 312, 314 endocrine disrupting chemicals (EDCs), 176, 361, 368, 372b, 378 energy. See also carbon dioxide (CO2) emissions; fossil fuel combustion; greenhouse gases access to, 288–89 biofuels, 310–11 biomass burning and household air pollution (HAP), 289–92, 293f, 313 choices about, 285 climate and occupational implications of fossil fuels, 297–301 conservation and efficiency, 312–13 fossil fuels vs. renewables and postcombustion world, 285–88 future prospects, 478 health linkages (overview), 285, 286f hydroelectric, 81, 308–9 intensity, 47f noncommunicable disease and, 167–69 nuclear, 301, 306–7 outdoor air pollution, 292–93, 296–97 per dollar of GDP, 46, 47f for planetary health, 313–15 primary global sources (1800–2017), 287f smart grids, 312 solar, 307–8 storage technologies, 311–12 subsidies and social investments in LPG, India, 294–96b wind, 308 entomological inoculation rate (EIR), 148f

Index 503

environmental economics, 403 environmental identity, 229–30 environmental impact assessments, 159 environmental profit and loss (EP&L), 441–45, 442–44f Environmental Protection Agency, US (EPA), 376–77, 379 epidemiologic transition, 166 equity and inequity. See also low- and middle-income countries in cities, 343–44, 347 consumption and, 41–46, 43f, 50 definitions of success and, 401–2 distributive justice, 459–63 economic valuation and distributional equity, 416–17 ethics and, 12–13 food resources and, 126, 134–35 future prospects, 479–80 GDP as blind to inequality, 396 infectious disease and, 490 mental health and, 232–35 transportation and, 338–39, 340 ethanol, as biofuel, 310 ethics climate change and, 454–55 definition of terms, 455 distributive justice, 459–63 ethical standards and judgments, 455–56 foundations for planetary health ethics, 456 four pillars of bioethics, 453 history of ethical frameworks, 454 human rights and, 466–67 intergenerational responsibility, 457 more-than-human world, extending rights to, 457–59 new ethical terrain, 11–13 precautionary principle, 464 right to know, 464–66 eugenics, 47–48 European Chemical Agency, 376 European Convention on Human Rights, 466 eutrophication, 77–78 evolution, 24, 475

existence value, 271 externalities in business blueprint, 440, 441 GDP, omission from, 395 internalization of, 434–36, 437f negative, export of, 396 negative production externality, 408–9, 408f positive, capturing, 436–37, 438f of prosocial behavior, 274 quantifying, 13 Smith’s “invisible hand” and market failures, 391 extinction rates, 95, 96f Extinction Rebellion, 231 Family Planning and Health Services Project (FPHSP), 59–61b family planning programs, 54–56, 57–64b, 64–66 farmer’s markets, 341 fertility rates, 53–54, 231 fertilizers, 75–79, 76f, 116, 155–58 fire for cooking, 289–92 land cleared with, 13, 84, 175 wildfires, 73, 224, 248–49 fisheries aquaculture, 129–31, 252 biomass of large predatory fish (1700 and 2010), 388t climate change and, 118, 252 overharvesting and depletion, 97, 118, 157–58, 177 flooding cities and, 328–29, 330 dam failures and, 309 equity and, 344, 361 health impacts of, 248 from Hurricane Katrina, 194 sea-level rise and, 9, 73 foodborne diseases, 251 food systems. See also agriculture atmospheric carbon dioxide, impact of, 121, 122–24b, 126, 175 climate change impacts, 125–26, 175 dietary shift, need for, 133–36

504  Index

dietary transition, 114, 136, 174 equity and, 126, 134–35 future prospects, 478 government policy, private sector, and, 136 greenhouse gas emissions by food source, 134f historical and projected global dietary energy supply, 117f impacts on natural systems, 116 migration and, 211–12 nutrition, malnutrition, and hunger, 114–16, 115b, 175 overharvesting and access, 119 pests, pathogens and, 120 pollinators and, 120–21, 177 pollution and, 124–25 population growth and per capita food production, 113, 127 soil degradation and, 118 technological innovations in production, 127–32 triple challenge, 126–27 urban, 333, 340–42 violence and food insecurity, 207 waste, 133, 342 water scarcity and, 118 footprint, ecological ballooning of, 5 consumption, population growth, and, 50 of energy industry, 299 food production and, 116, 126, 127, 132–36, 134f, 478 Global Footprint Network (GFN), 50, 387 global hectares and Earth Overshoot Day, 387 globalization and, 44 in human history, 38, 42f private sector and, 479 urban, 325, 327, 331, 334, 339, 344, 478–79 forest transitions, 83, 85 fossil fuel combustion. See also carbon dioxide (CO2) emissions; greenhouse gases air pollution from, 98, 292–93, 396–97 annual output (1800, 1990, and 2016), 388t

carbon intensity, 297 climate change and, 297–301, 313–14 coal, 293, 296, 300, 300f hydraulic fracturing (“fracking”), 299, 302b leaks and spills, 301 liquefied petroleum gas (LPG), 294– 96bg natural gas, 299 nitrogen from, 76 noncommunicable disease and, 167, 168–69 occupational hazards and local environmental impacts, 299–301 petroleum, 296–97 postcombustion world and renewables vs., 285–88, 477, 478 tar sand oil production, 298–99 unconventional oil and gas development, 302–6b Francis, Pope, 482 free air carbon dioxide enhancement (FACE) experiments, 122–23b free-rider problems, 275, 427 fuel stacking, 291 gardens, rooftop and vertical, 334, 335f genetically modified crops, 129 gentrification, 344 Genuine Progress Indicator (GPI), 397– 98 geography, medical, 19–20 Give It Up (GIU) campaign, India, 295b Global Burden of Disease (GBD) Study, 115b, 165, 168, 289, 420n Global Covenant of Mayors for Climate and Energy, 346 “global health,” 30–31 globalization, 44, 489–90, 494 governance business and, 447 cities and, 326–27 commons and, 409 current global context, 428–30 economics and, 406 infectious disease and, 160 migration and, 213 for planetary health, 425–26, 434 political power, role of, 13

Index 505

theoretical and practical issues, 427–28 on toxic chemicals, absence of, 371, 372b government policies. See policy Great Transition, 483 green chemistry, 378–82, 380b Green Climate Fund, 427 Green Gyms initiative (South Tyneside, England), 276 greenhouse gases. See also carbon dioxide (CO2) emissions; climate change from agriculture, 116 as backloaded problem, 454 biofuels and, 310 from building sector, 328 business models and, 432, 433, 434 cities and, 171, 326, 329–30, 334 from coal, 167f consumption and, 49 food system and, 133, 134f health consequences of, 17 hydropower and, 309 inequity and, 12, 459 mitigation, 75 from natural biosphere, 73 nitrous oxide, 78–79 nuclear power, benefit of, 301 policy on, 51 from solid waste, 329, 333 variation by country, per capita, 44 green urbanism, 334–36 grid, electrical, 312, 314 grief, ecological, 230 gross domestic product (GDP), 46, 47f, 262–64, 393–400 gross national happiness, 52, 263–64 growth, economic vs. wellbeing, 393, 479 Gulf of Mexico dead zone, 77, 78f habitat destruction and fragmentation, 149–50 happiness Buddha and Aristotle on, 261–62 conservation of environments and, 270–71 definition of terms, 262 gross national happiness, 52, 263–64 Happy Planet Index (HPI), 398–99

metrics and measurement, 262–67 nature access and, 269–70 physical health and, 268 policy design and delivery and, 277– 78 prosocial behavior and, 271–77 resource intensity vs. social factors, 267–68 social norms, reciprocal cooperation, and, 274–77 subjective self-assessment, 265, 266b sustainable behaviors and, 236 trust and, 273–74, 274f, 276 hantaviruses, 151–52, 155 Hardin, Garrett, 426, 454 Hartwick’s rule, 404 health, human. See specific topics, such as disease, infectious or mental health healthy life expectancy (HALE), 421 healthy life year (HLY), 421 heat climate change and, 246–48, 248f health effects of, 169 mental health and, 225–26, 225f urban heat island effect, 246–47, 328, 329–30, 333 Heidegger, Martin, 458 herbicides, 98, 252, 372b Holdren, John P., 37 hope, 14, 494 Horton, Richard, 29 Hotelling’s rule, 404 household air pollution (HAP), 289–92, 293f, 313 housing, inadequate, 173 human capital, 411 Human Development Index (HDI), 265, 398 human rights, 466–67 hurricanes, 194, 224, 462f hydraulic fracturing (“fracking”), 299, 302b hydroelectric power, 81, 308–9 I = PAT equation, 37, 52 identity, environmental, 229–30 Inclusive Wellbeing Index (IWI), 398 Index of Sustainable Economic Welfare (ISEW), 397–98

506  Index

India Bhopal chemical disaster, 366 coal combustion, 296 indoor and outdoor air pollution, 291 Kerala bottling plant suspension, 436 LPG social investment initiatives, 294–96b Mumbai beach cleanup campaign, 274 population control in, 48 rights conferred on Ganges and Yamuna, 458 Slum Networking Project, 344 Indigenous communities, 234, 270–71, 459 industrial revolution, fourth, 440 inequities. See equity and inequity; poverty infant mortality, 57–58b infectious disease. See disease, infectious insects, 120, 363. See also pesticides; pollinators instrumental value, 457–58 integrated exposure–response (IER) curves, 293f internally displaced person, 198b intellectual capital, 412 Inter-agency Working Group on Reproductive Health in Crises (IAWG), 209–10b intergenerational responsibility, 457 intrinsic value, 457–58 Inuit communities, 234 IPBES (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services), 230, 410n, 458 Iraq War, 208 Irish potato famine, 190, 489 iron deficiency, 123b ischemic heart disease, 166–167, 168 Islamic Declaration on Climate Change, 482 Jakarta, Indonesia, 330 Jigme Singye Wanchuk, King of Bhutan, 263 Kant, Immanuel, 459 Kennedy, Robert, 394, 395

Kering, 441–45, 442–44f kidney disease, 170 King, Martin Luther, Jr., 14 Kuznets, Simon, 263 Lake Malawi, 157–58 Lancet Commission, 8, 29, 30f, 102, 174 land use and land cover conservation efforts, 83 defined, 79 drivers of change, 82–84 future trends, 84–85 global patterns, 79–82 historical statistics, 388t infectious disease and, 152–55 land management changes, 84 spatial distribution of biomes, 79, 80f urban, 327, 332–33 Lautenberg Act (US), 376–77 lead-based paint, 367 life cycle analysis, 134f, 293, 297, 298f, 301, 308, 310, 311, 328, 432, 447, 479, life evaluations, 266b life expectancy, healthy, 401–2, 421 liquefied petroleum gas (LPG), 294–96bg Local Governments for Sustainability, 346 loss and damage (L&D), 462–63 lowest observed adverse effect level (LOAEL), 377–78 Lyme disease, 145f, 151, 251 malaria, 146–48, 153–54, 156, 309 Malthus, Thomas, 47, 113 mangroves, loss of, 81–82 McMichael, Anthony J., 17–18, 18f, 20, 26, 28–29 Meadows, Donella, 28, 31 meat substitutes, 135, 445–47 Medellín, Colombia, 344 mental health access to nature and, 228–30, 492 air pollution and, 226 awareness of environmental change, effects of, 230–32, 233f climate change and, 253 depression, 221 disasters and, 222–24

Index 507

drought and, 226 heat and, 225–26, 225f inequity and, 232–35 migration and, 212, 226–27 mitigation, adaptation, agency, and collective action, 235–37 physical health, link to, 221 preexisting conditions, 235 PTSD, 223–24, 235 social networks and, 222 urbanization and, 227 mercury contamination, 177, 366–67 metabolic disease, 114, 115b metal contamination, 176–77, 366–67 microgardens, 341–42 migration and displacement, human adaptive and maladaptive, 201 ancestral Pueblo peoples, 190 causal links between conflict and, 206–7 Central American, 193 climate change and, 149, 201, 252 conflict, links to, 206–07 dam construction, related to, 309 Darfur conflict and, 191–92 disease and, 149 drivers of, 193–96, 195f environmental refugees, 463 glossary, 198b health implications, 208–12 Irish potato famine, 190 managed retreat, 198b, 201 mental health and, 226–27 nutrition and, 211-21 Oklahoma Dust Bowl, 190–91 patterns of, 197–201, 199f, 200f primary vs. secondary factors, 193 rural-to-urban, 173 sea-level rise and, 194, 198b, 463 slow- vs. rapid-onset, 193 social networks among, 199–200 solutions, 212–13 sources and destinations, 195, 196t, 197f Tangier Islands, Chesapeake Bay, 193 trapped populations, 200f women’s health and, 209–11b Milan Urban Food Policy Pact, 340–41 Millennium Development Goals (MDGs), 288

Millennium Ecosystem Assessment (MA), 410 Minimum Initial Service Package (MISP) standards, 210b Montreal Protocol, 427 mosquitoes, 146–48, 153, 154, 155, 250–51 Mothers Out Front, 237f movement building, 13, 483 Muir, John, 454 multicapital framework, 410–13, 412f nanomaterials, 372–73b natural capital, 412–13, 416 Natural Capital Coalition, 430 natural gas, 299, 301–306b natural resource economics, 404 nature, human relationship with about, 8–9 ecological grief, 230 happiness and nature contact, 269–70 health benefits of, 173 mental health and contact with nature, 228–30, 491–92 rights extended to more-than-human world, 457–59 social bonds and, 270 spiritual connection, 482 urban access, 333 neighborhood greenness, 228–29 neo-Malthusian approach, 204–5 neonicotinoids, 363, 372b nitrogen cycle, 75–79, 76f, 365. See also fertilizers nitrous oxide, 78–79 noise, 172, 173, 302b, 332 no observed adverse effect level (NOAEL), 361, 377 noncommunicable diseases 165–88 normative economics, 403 “No Wrong Door” (NWD) initiatives, 277–78 nuclear energy, 301, 306–7 nuclear weapons, 26–27, 307 nutrition. See food systems occupations. See workers and occupational hazards oil palm cultivation, 175

508  Index

oil spills, 301 Oklahoma Dust Bowl, 190–91 older adults air pollution and, 168 climate change and, 73 mental health and, 235 nature, exposure to, 229 population trends and, 39 vulnerability of, 246, 333, 340 100 Resilient Cities network, 346 Ostrom, Elinor, 275–77, 426, 454 overarching themes, 8 ozone, 168, 249 PAHAL (direct benefit transfer) initiative, India, 294–95b palm oil, 175 pandemic, 488–94 parasites, defined, 142–43b Paris agreement (UNFCCC), 346, 428–29 particulate matter (PM) household air pollution (HAP) and, 289, 291 integrated exposure–response (IER) curves, 293f livestock operations and, 78 noncommunicable disease and, 168 from petroleum combustion, 296 in soil, 100 pathogens, defined, 142–43b. See also disease, infectious peatlands, 82 permits, environmental, 431b persistent organic pollutants (POPs), 176, 364–65 pesticides. See also chemicals, toxic agriculture and, 116, 252 Bhopal disaster, India, 366 climate change and, 146–47, 252 DDT, 146, 369 endocrine disrupters, 176 governance, absence of, 371 history of environmentalism and, 25–26 human toxicity, 365 infectious disease and, 155–56 neonicotinoids, 363, 372b Pesticides in the Diets of Infants and Children report (NAS), 367

pollinators and, 121, 363 pollution and, 98, 99, 100 production of, 101 regulation and, 361 phosphorus, 75–79, 155–56 photovoltaics (PV), 307–08 physical activity, 171–72 Physicians for Social Responsibility (PSR), 26–28 Physicians for the Prevention of Nuclear War (IPPNW), 27–28 planetary boundaries framework, 29, 389, 390f, 432–33, 441 Planetary Health Alliance, 28–29 planetary health, history of conceptual framework, assembly of, 28–29 “global health” and, 30–31 McMichael and, 17–18, 20, 26, 28–29 medical geography, 19–20 nuclear weapons and PSR, 26–28 post-WWII environmental thinking, systems ecology, and environmental health, 21–26 systems thinking and, 20 plastics production and water pollution, 99, 100f Platform on Disaster Displacement, 198b policy dietary, 136 economic policy instruments for planetary health, 430, 431t family planning and reproductive health programs, 54–56, 57–64b, 64–66 GDP and, 396–97 infectious disease and, 158–59 “No Wrong Door” (NWD) initiatives, 277–78 political leadership, importance of, 428 on population and consumption, 47–51 right-to-know laws, 378 on toxic chemicals, 371, 372–73b, 378 pollen, 250, 250f pollinators, 96–97, 120–21, 177, 363 pollution. See also air pollution; chemicals, toxic; fertilizers chemical, 100–101, 252

Index 509

cities and, 327 defined, 97 eutrophication, 77–78 food production and, 124–25 historical statistics, 388t infectious disease and, 155–58 soil, 99–100, 124 sources of, 97–98 water, 99, 100, 124, 303b polychlorinated biphenyls (PCBs), 364, 369 population. See also migration and displacement, human conflict and, 205 contentious debates on, 47–49 demographic dividend, 55 family planning and reproductive health programs, 54–56, 57–64b, 64–66 fertility rates, 53–54 food production and, 113, 127 future prospects, 477 history of growth, 38–39 I = PAT equation, 37, 52 policies on, 47–51 population momentum, 38 projections, 39–40, 39f urbanization and, 39–40, 41f Population, Health, and Environment (PHE) projects, 62–64b positive economics, 403 postcombustion world, 287–88, 477, 478 potato blight, 190 poverty. See also equity and inequity climate change and, 200f conflict and, 205 economic development and, 45, 50 eradication of, 463 mental health and, 221 migration and, 194, 199–200 noncommunicable disease and, 165 number living in extreme poverty, 3, 4f urbanization and, 170–71 precautionary principle, 464 pregnancies, unintentional, 54, 55 prosocial behavior, 271–77 public goods, 409 Pueblo peoples, ancestral (Anasazi), 190

quality-adjusted life years (QALYs), 420–21, 421f Quammen, David, 489 Rall, David, 375 Raworth, Kate, 399–400 REACH regulation (EU), 376 recycling of batteries, 308, 312, 366 discouraged by GDP, 395 downcycling, 439 e-waste centers in LMICs, 99, 366 food programs, 342 materials replaced with recycled alternatives, 442f, 444 solar energy and, 308 of urban solid waste, 336 REDD and REDD+, 461–62 refugee, 198b refugee camps, 149, 208, 209–11b. See also migration and displacement, human relational value, 458 relocalization, 479 renewable energy, 81, 307–11 reproductive health programs, 54–56, 57–64b, 64–66, 209–10b reservoir hosts, 142b resilience, 237–38, 492–93 resource wars, 203b revealed preference techniques, 415 right to know, 378, 464–66 Rio Convention, 429 Rockefeller Foundation, 20, 29 Rockefeller-Lancet Commission on Planetary Health, 8, 29 Romania, 48 Rosenberg, Charles E., 20 salinization and saltwater intrusion, 9–10, 86, 169, 251, 253, 331 salt intake, 169–70 Santiago, Chile, 344, 445 schistosomiasis, 157–58, 157f, 309 School Strike movement, 457, 476f science-based targets, 433 sea-level rise arable land and, 28, 125 causes of, 245 Jakarta and, 330

510  Index

migration and, 194, 198b, 463 noncommunicable disease and, 169–70 saltwater intrusion from, 9–10, 86, 169, 251, 253, 331 Tangier Islands, Chesapeake Bay, and, 193 tipping point, 73, 74f urban flooding and, 330 sexuality education, 65–66 sexually transmitted diseases, 209–10b, 211 sexual violence, 208, 209–10b, 225, 225f silicosis, 300 Singapore, 277 slums, 343, 344 smart grids, 312, 314 Smith, Adam, 391 social action. See movement building social capital, 273–74, 274f, 412 social networks and connectedness community initiatives, 236–37 ethics and, 455 future prospects, 477, 479 happiness and, 270–71 mental health and, 212, 222, 224 migration and, 196, 199, 227 social urbanism, 344 soils degradation of, 85–89, 118 loss of, 85 metal contamination, 176–77 microbe research, 129 no-till agriculture and regeneration of, 131–32 pollution of, 99–100, 124 regenerative agricultural practices and, 89 solar energy, 307–8 solastalgia, 230 species richness, 145, 151. See also biodiversity loss spillover, 488 spiritual dimension, 13–14, 66, 482 sprawl, urban, 331, 333 stated preference techniques, 416 stewardship, 13–14, 436 Stiglitz, Joseph, 262 Stockholm Declaration on the Human Environment, 466

stress recovery theory, 229 stunting, 175 surprises, in complex systems, 253, 490 Sustainable Development Goals (SDGs), 178f, 288, 398, 429, 429f System of Economic Environmental Accounts (SEEA), 398 System of National Accounts (SNA), 398 systems thinking, 9, 20, 25–26, 179, 332f, 342–43, 404, 490 Tangier Islands, Chesapeake Bay, 193 tar sand oil production, 298–99 taxes, 52, 430, 431b temporal dimension of planetary health, 426 thalidomide, 367, 375 Thunberg, Greta, 475–76, 476f, 480, 483 TiPED (endocrine disruption testing), 378 toxic exposures. See chemicals, toxic Toxic Substances Control Act (US), 376–77 tragedy of the commons, 409, 426, 454. See also common pool resources Transition Towns, 346 transit-oriented development (TOD), 340 transportation, 171–72, 314–15, 332, 336–40 trapped populations, 200f tropical forests, 83, 84–85, 153–54, 175 trust and happiness, 273–74, 274f, 276 undernutrition, 175 United Nations (UN) Framework Convention on Climate Change (UNFCCC), 427, 428–29, 462–63 Human Development Index, 265, 398 Human Rights Council, 466 Sustainable Development Goals (SDGs), 178f, 288, 398, 429, 429f World Happiness Reports and, 264 Universal Declaration of Human Rights, 466 uranium mining, 301, 306 urban heat island, 328, 333 urbanization and urban environments biosphere, impact on, 327–29 buildings, better, 334

Index 511

crowding, 173 dissemination and translation of innovations, 345 environmental change, impacts on and of, 171–74, 329–31 equity and, 343–44, 347 food systems and urban farming, 340–42 future of the planet and, 326–27 future prospects, 478–79 gentrification, 338, 339, 344, 345 green urbanism, 334–36 health and, 331–33, 332f higher-density development, 334 housing, inadequate, 173 infectious disease and, 153, 154–55 land use, 86 mental health and, 227 nature and greenspace, disconnect from, 173 new urban science and evidence base, 342–43 noise and, 172 noncommunicable disease and, 170–74 partnerships, networks, and coalitions, 346 population and, 39–40, 41f social urbanism, 344 soil degradation and, 86 transportation, sustainable, 336–40 urban heat island effect, 246–47, 328, 329–30, 333 zoning, 334 valuation, economic, 413–20 value, in ethics (instrumental, intrinsic, and relational), 457–58 value chain, 432, 440–41, 442 value transfer, 416 vector-borne diseases, 143t, 143f, 143, 148, 250–51 vertical gardens, 334 violence. See also conflict   heat and, 225, 225f interpersonal, 204, 208, 209–10b vision, aspirational, 480–81, 481t war. See conflict Ward, Barbara, 21, 23, 31

waste batteries, 312 electronic, 367 food, 133, 342 nuclear, 307 pharmaceutical, 372b solid, 328, 329, 333, 388t unconventional oil and gas development and, 303–4b urban, 329, 333 zero-waste approach, 336, 440, 445 wastewater, 328, 331, 333, 372, 445 waterborne diseases, 251 water pollution, 99, 100f, 124, 303b water resources. See also wastewater conservation strategies, 94 demand management, 92–94 demands and projections, 92, 93f food system and, 118 geographic differences in water stress, 91, 91f global stocks of, 89, 90f impounding, 132 sustainability strategy, 94 urban, 328, 333 water scarcity and drought. See also flooding about, 89–94 cities and, 330–31 climate change and, 125 conflict and, 206 demand and projections, 92, 93f, 93t mental health and, 226 food production and, 118 migration, conflict, and, 190–92 welfare economics, 406–8 wellbeing. See also happiness aggregate, maximizing, 401–2 ecosystem services and, 410, 411f GDP vs., 393–97 Inclusive Wellbeing Index (IWI), 398 measuring and valuing, 421–22 subjective assessment of, 265, 266b, 405, 422 wellbeing economics, 405 Wellcome Trust, 29 wetlands, 81–82, 153, 156, 438 wilderness, land in, 388t

512  Index

wind power, 308 women biomass fuels and, 291, 313 climate-change vulnerability, 234, 251–52, 253 family planning, population control, and, 48–50, 54–55, 57–58b, 67, 477 fertility rates, 53–54, 231 Indian PBG programs and, 295b iron deficiency in, 123b PHE projects and, 62–63b in refugee camps, 209–11b Sustainable Development Goals and, 288 workers and occupational hazards biofuels and, 311 fossil fuels, 299–301 mental health and, 234 nuclear energy and, 301 toxic chemicals and, 365–66 World Commission on Environment and Development, 31

World Happiness Report, 264-65, 267 World Health Organization (WHO) Air Pollution and Health Conference, 429 climate change and, 17–18, 246 Global Burden of Disease estimates, 289n International Agency for Research on Cancer, 366 malaria estimates, 146 on mental health, 221 on noncommunicable disease, 165, 166f on pollution, 98–99, 168, 171, 291, 327 World Trade Organization, 428 Xe-Pian Xe-Namnoy hydroelectric project, Laos, 309 Yu, Charles, 494 zoonotic disease, 143f, 143t, 143–45, 149, 151, 152, 154, 488–89

About the editors Samuel Myers, MD, MPH is a Principal Research Scientist at the Harvard T.H. Chan School of Public Health and founding Director of the Planetary Health Alliance. Dr. Myers served as a Commissioner on the Lancet-Rockefeller Foundation Commission on Planetary Health. He was the inaugural recipient of the Arrell Global Food Innovation Award in 2018 for research quantifying the impacts of environmental change on human nutrition. He has also been awarded the Prince Albert II of Monaco—Institut Pasteur Award for research at the interface of global environmental change and human health. Howard

Frumkin,

MD,

DrPH

is Photo by Kelsey Wirth

Emeritus Professor of Environmental and Occupational Health Sciences at the University of Washington School of Public Health, where he was Dean from 2010–2016. He was previously head of Our Planet, Our Health at the Wellcome Trust and director of the

National Center for Environmental Health and Agency for Toxic Substances and Disease Registry at the US Centers for Disease Control and Prevention.  His other books include Environmental Health: From Global to Local (3rd edition, 2016) and Making Healthy Places: Designing and Building for Health, Well-being, and Sustainability (2011).

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