The Planetary and Human Health Initiative

How this changed paradigm of looking at environmental health can change your life

This past week, TIME awarded six individuals, including myself, the Earth Award for 2025. While the recognition is truly an honor, my real hope is that the Earth Award serves to kickstart awareness about the vital connection of our individual human health with planetary health. Indeed, this integral force that connects all life is what brought me to this work – and it’s what keeps me here, no matter the challenges or the headwinds.

After 20 years as a scientist and surgeon, 12 years as a policymaker in Washington, and a decade and a half innovating and building health companies, I approach conservation and climate action from the perspective of what science tells us, both about the specific ways the world around us is changing and how the pace of this change today, for the first time in human history, is outstripping evolution of us as a human species. These are big issues, so big they seem overwhelming and sometimes distant, so big they can be put out of mind — but by viewing them from the vantage point of why they matter to “me, my health, my well being (and the health of my children),” they become more in focus, more understandable, more digestible, more doable. And they introduce a sense of moral responsibility to act now out of respect for the generations to follow.

The world around us is more than just a backdrop for human existence — it is the foundation of our health. What I’ve come to more fully understand in my winding journey from medical student to chair of The Nature Conservancy (TNC) is that human health and planetary health are inextricably linked, and this understanding offers a powerful way to approach the escalating environmental challenges of our time. Rather than viewing nature as something separate from us, we must recognize that the air we breathe, the water we drink, the food we eat, and the climate we experience all directly affect our well-being, including being as healthy and as productive as possible. This perspective shifts the conversation away from abstract environmental issues to something deeply personal: our own health and the health of our children and grandchildren.

The journey

Through my responsibilities at The Nature Conservancy, I spend much of my time around the conviction that human health cannot be fully addressed without caring for planetary health. The specific mission of TNC is “to conserve the lands and waters on which all life depends,” reflecting our commitment to protect and restore natural ecosystems for the purpose of ensuring a sustainable future for both people and nature. And it’s this health of people that I underscore.

People ask what brought me to this point, and I go back to my earliest days of growing up on five acres with woods and horses out back, as a child our annual summer vacations always at the nature-centered Cumberland Mountain State Park, to camping and exploring in scouting. But by far, the single greatest influence that brought me to nature has been my wife Tracy, who for her entire life has placed nature and a love for animals and the outdoors as central to her being. She provides the North Star for all our conservation initiatives.

Tracy and me at the edge of our favorite vernal pool (the “Fairy Pond“) on our farm Sinking Creek. Vernal pools are temporary, seasonal wetlands that typically fill with water in the spring or fall and dry up in winter. They provide essential habitat for a wide variety of plant and animal species, especially amphibians that breed in the pools. Tracy’s commitment to and love for nature serves as a “North Star” for me.

Was there an epiphany moment for me? Not really, but the closest thing was a revelation that occurred when I was a young heart transplant surgeon who dreamed of doing lung transplants for the thousands of patients who were dying each year of irreversible lung disease.

At the time lung transplants were impossible because the necessary immunosuppressant regiment prevented healing of the sutured anastomosis connecting the main airways. But then two Norwegian scientists discovered in a soil sample a specific fungus (Tolypocladium inflatum) that had powerful new immune suppressing properties that revolutionized transplantation. From that discovery in nature, they developed the drug cyclosporine — and it was that fungus from nature that opened the door for me and others to successfully perform lung transplants for the first time ever.

And over 50,000 lifesaving lung transplants have been performed since. In fact, the longest surviving lung transplant patient in the world today is a woman I transplanted at Vanderbilt 36 years ago. The discovery not only revolutionized lung transplantation but also transformed the field of medicine by enabling successful transplants of kidneys, hearts, livers and other organs, extending the lives of countless patients who would have otherwise died from organ failure.

This breakthrough taught me a critical point: nature-based solutions are all around us. Nature is connected to health. Planetary health is connected to human health. It’s why the World Health Organization has declared: “Climate change is the single biggest health threat facing humanity.”

My friend Dr. Katharine Hayhoe, a renowned climate scientist and Chief Scientist for TNC, echoes this perspective. She emphasizes that the science is clear—climate change and biodiversity loss are not just environmental crises but also health crises. The heat waves, floods, and wildfires we see increasing around the world are not just weather events; they contribute to respiratory illnesses, cardiovascular disease, and mental health challenges. For example, rising temperatures (Note: 2024 was the hottest year since global records began 175 years ago) lead to more heat-related illnesses, exacerbate air pollution, and create conditions for the spread of vector-borne diseases like Lyme disease and malaria.

Examples

The health impacts of environmental degradation extend far beyond infectious diseases. The Green Heart Initiative in Louisville, Kentucky, found in a TNC- and NIH-funded, controlled trial that simply living in greener neighborhoods lowers markers of inflammation (C-reactive protein) associated with heart disease and stroke. Trees, it turns out, are medicine. Even looking at images of nature has been shown to reduce pain sensitivity. These findings reinforce that conservation is not just about protecting landscapes but about fostering healthier lives and healthier communities.

Conservation, biodiversity loss, climate action, and sustainable use of natural resources should not be polarizing or partisan issues. A quarter of century ago they were not. The paradigm shift — viewing planetary health as a prerequisite for human health—has profound implications. It reframes environmental action in a way that resonates with people across political and ideological spectrums. Climate change and nature loss can sometimes feel abstract or politically charged, but health is personal. No one wants their child to struggle with asthma because of air pollution, nor do they want their elderly parents to suffer from heatstroke due to rising temperatures. By centering human health in the conversation, we can move past divisive rhetoric and focus on solutions that benefit everyone.

Another critical element of planetary and human health is food. Last year I testified before Congress on the growing “food is medicine” movement. What we eat clearly impacts our productivity, our quality of life, and how long we live. And then there is food security. The changing climate and increasingly extreme weather patterns disrupt agricultural systems, leading to food shortages and declining nutrition. Higher temperatures make crops more vulnerable to pests, toxins, and extreme weather events.

Tracy and I have a farm in southwest Virginia, in the heart of central Appalachia. With her leadership, we actively engage in conservation practices including rotational grazing, planting trees, riparian borders, silvopasture, and prescribed burns for land health. Regenerative agriculture—farming practices that restore soil health, enhance biodiversity, and improve water retention—provides a solution that benefits both the planet and human nutrition. This helps create sustainable food systems that support long-term health and economic stability.

Mental health, often overlooked in traditional environmental discussions, is yet another explosive dimension of the planetary-human health connection. Studies show that climate change-related stress and anxiety are on the rise, particularly among young people. The loss of natural spaces, biodiversity decline, and environmental uncertainty contribute to feelings of helplessness and distress. Yet, spending time in nature has been shown to reduce anxiety, lower blood pressure, and improve overall well-being. The physiological response of lowered cortisol (the stress hormone) levels is well documented. Recognizing nature as a fundamental component of mental health care opens the door to policies that prioritize nature spaces, urban tree planting, and conservation initiatives as public health strategies.

Role of the healthcare sector

As a doctor and builder of healthcare companies, I think a lot about the role of the healthcare sector in addressing sustainable energy use and the changing climate. In board meetings of health companies whose boards I sit on, I ask the simple question, “How are the hotter days and increasingly unstable weather patterns affecting our business?” Sometimes eyes roll when I initially ask it, but when the educated answers come back, the impact is typically eye-opening.

The healthcare sector makes up 18% of the U.S. economy and is responsible for approximately 9% of the unhealthy greenhouse gas emissions in the U.S. If hospitals, health insurance companies, and healthcare providers integrate planetary health into their mission and operations, they can become powerful allies in advancing environmental solutions. Doctors and nurses are among the most trusted voices in society, and their advocacy for clean air, clean water, and sustainable food systems can mobilize public support in ways that traditional environmental messaging often struggles to achieve. People listen to trusted sources.

This is why Tracy and I are committed to adding the concept of “planetary and human health” to medical and nursing school curricula. It’s practically nonexistent today, in spite of the fact medical students today are hungry for the information and eager to be a part of developing solutions. We recently worked with Meharry Medical School in Nashville to establish an award and fellowship for medical and PhD students who wish to advance a career in Planetary and Human Health.

We envision students studying the health impacts of the changing climate, exploring such topics as:

· Impact on Chronic Diseases: Examining how climate exacerbates conditions such as cardiovascular and respiratory diseases due to increased air pollution and heat stress.

· Infectious and Vector-Borne Diseases: Investigating the expanded range and incidence of diseases like malaria and dengue fever as changing temperatures and precipitation patterns affect mosquito and tick populations.

· Mental Health Effects: Assessing the psychological impacts of climate-related events, including increased anxiety, depression, and post-traumatic stress disorder resulting from extreme weather events and displacement.

· Disproportionate Impact on Vulnerable Populations: Understanding how marginalized groups, such as low-income communities, the elderly, and children, are more susceptible to health issues stemming from climate change due to factors like limited access to healthcare and resources.

· Food: Exploring how a changing climate affects food security and nutrition, leading to malnutrition and related health problems as agricultural yields and food quality decline.

· Heat-Related Illnesses: Studying the increase in heat-related conditions, such as heatstroke and dehydration, as global temperatures rise and heatwaves become more frequent.

· Healthcare System Preparedness: Evaluating how climate change challenges healthcare infrastructure and delivery, emphasizing the need for resilient systems to manage increased disease burdens and disaster response.

I have seen every one of these in my own practice in medicine as well as in my on-the-ground international medical relief work in response to disasters throughout Africa, in Haiti, in Sri Lanka, in New Orleans. Who better to share this message to their colleagues and to the public than the healthcare providers of tomorrow?

We hope this initiative will become a model for other medical schools around the country, supporting the science and advancing the understanding of the emerging field on this human health side of the equation.

And on the other side of the equation, the planetary health side, Tracy and I six months ago helped launch a major new program at The Nature Conservancy called the Planetary and Human Health Initiative. The vision is to systematically investigate and establish health-positive conservation practices that simultaneously benefit people and the planet. It is assembling a diverse, interdisciplinary team of scientists spanning biology, medicine, ecology, public health, sustainable energy, anthropology, and economics with a focus on solutions, recognizing that protecting nature is essential to protecting people. By embedding health outcomes into conservation, sustainable use of natural resources, and climate action, we believe this new discipline can accelerate progress on climate resilience, biodiversity protection, and equitable environmental solutions.

Why am I optimistic?

I am optimistic about our ability to address the dual crises of biodiversity loss and climate change. Yes, we face real headwinds—especially political ones. But I believe we have a strong foundation for progress, and here’s why:

First, most Americans understand the problem. That was not true a decade ago. That alone gives me hope. Despite what we hear from some elected officials, the majority of the American people recognize that climate change is real and already having a negative impact on their lives. Public opinion polls show that 60 to 70% of Americans recognize climate change as a serious concern, and 94% support protecting nature. However, only about 8% feel activated to take action. That is our challenge. The missing link is communication—connecting the dots between planetary health and personal well-being in ways that inspire action. As Dr. Hayhoe puts it, the challenge is to bridge the gap between knowledge (what we know), emotion (why we care), and action (what we do about it).

My years in politics and policy have taught me that widespread awareness is a powerful force. Public opinion is shifting in the right direction. We must accelerate that. When the public leads, in a democracy policy eventually follows.

Second, the science is clear—and growing stronger by the day. An overwhelming majority of scientists agree that climate change is real, and that human activity—especially the burning of fossil fuels—is a major driver. The National Academy of Medicine, the most respected body of doctors and scientists in the U.S., concludes: “Climate change is one of the most pressing existential threats to the future of human health.”

The same scientific consensus exists around biodiversity loss: the rapid degradation of ecosystems and extinction of species is harming our health, our food systems, and our economies. We can’t ignore it. Knowledge is power—and the more we understand, the better we can act. Science at its best, defines nature. It’s humanity’s best chance to define truth. And it’s this truth that is the best weapon to destroy the misinformation that haunts every corner. Today’s science gives us both the urgency and the tools to make informed, targeted progress.

Third, innovation and advances in technology are moving at breathtaking speed. For example, Direct Air Capture is rapidly progressing with machines that pull carbon dioxide directly out of the atmosphere and store it underground or use it to make sustainable fuels and materials. And today, thanks to falling costs of renewable electricity, we can now produce “green hydrogen” by splitting water molecules using clean power from wind and solar—without emitting any carbon. Another example is the use of next-generation nuclear technology that is safer, more flexible, and more affordable than past models. Small Modular Reactors are compact power plants that can be built in factories and deployed to power cities or rural areas with zero emissions. None of these technologies are silver bullets, but each is representative of potential partial solutions to the challenges we face today. They help define a future we can believe in.

Renewable energy sources like solar, wind, geothermal, hydro, and even nuclear are expanding rapidly. Over the past decade, the cost of solar has dropped by nearly 90% and wind by about 70%. Wind and solar are now cheaper than fossil fuels in many regions. Solar generation in the U.S. has grown more than eightfold since 2014; wind has more than doubled. And promising developments in fusion and battery storage are accelerating. These advances are creating a pathway to a cleaner, more sustainable, and ultimately more affordable energy future.

Then the question is, can such a big problem ever really be solved? That answer is absolutely yes. My own experiences in medicine, policy and science underly this optimism. I’ve seen other seemingly insurmountable issues addressed in real time, many equally politically polarized when initially identified.

Think back to the Civil Rights movement, the time when 45 percent of Americans smoked, when three million people were dying every year from the HIV virus, or when motor vehicle accidents were the number one cause of death of children. We have much to learn from the movements that addressed each of these. But what’s important is that they all begin with understanding the facts and the science, defining and agreeing on what the problem is, developing a plan to correct what we can, and innovating with technology to solve in the future what we can’t yet solve today.

But even before all this, we must all come to the table and we will only do that if we depolarize the issue, remove it from partisan politics, and align around the common theme that our health and wellbeing is at the core of everything we do — and that includes our physical, mental, and financial health so we can live fulfilling and prosperous lives.

Summary

Tracy’s and my personal goal is to help measurably improve the health of the planet — the streams and oceans, the air, and soils — and thereby maximize the health of all life on it, most notably humanity. For Tracy and me that means engaging in two arenas: protect biodiversity in our natural world and actively address our changing environment, especially the changing climate.

Learning about the unique biodiversity of the Amazon with The Nature Conservancy board in Brazil.

We seek to maximize the health of our environment by sharing our understanding (as doctor, policymaker, scientist, farmer) of how planetary health — the health of the world around us — directly impacts and in many ways determines our own individual health and wellbeing, and the health of our families. In other words, to maximize our own physical, mental and emotional health, we must together do everything we can to maximize the health of our environment.

We believe this paradigm of connecting planetary and human health offers a compelling new lens through which to address the climate and biodiversity crises. It is a framework that personalizes the stakes, making clear that conservation and environmental health is not just about preserving landscapes—it is about protecting ourselves, our families, and future generations. By embracing this approach, we believe we together can help build a movement that transcends politics and inspires collective action toward a healthier, more resilient world.