What if the most powerful medicine we have isn’t found in a pill or a procedure—but in the soil beneath our feet, the air we breathe, and the trees outside our window?
After decades in medicine—as a heart and lung transplant surgeon, a policymaker, and a healthcare entrepreneur—I’ve come to see something fundamental: the health of our planet and the health of our people are inseparable. Yet we’ve long treated them as two different conversations. That has to change.
Planetary health is human health.
The air we breathe, the water we drink, the food we eat, and the climate we live in directly shape our well-being. When these systems are degraded, our health suffers—physically, mentally, and economically. It’s time we reframe climate change and biodiversity loss for what they truly are: not just environmental threats but escalating human health crises.
A Surgeon’s Wake-Up Call
One of the most profound lessons I ever learned didn’t come from a textbook—it came from a fungus in the soil.
Early in my transplant career, lung transplantation was impossible. The medications we used suppressed the immune system but also prevented surgical healing. Then came cyclosporine, derived from a Norwegian fungus found in the dirt. It changed everything. That tiny organism helped unlock one of medicine’s greatest advances. It changed my life, and opened the door to the 50,000 lung transplants performed since.
The takeaway? Nature is not separate from health. Nature is medicine.
That insight has stuck with me ever since. It underlies my conviction. And today, it has never been more urgent.
The Science Is Clear—and Personal
Climate change is already reshaping how and where disease spreads. It worsens respiratory illness, increases cardiovascular stress, and fuels the rise of vector-borne diseases like Lyme and malaria. In 2024—the hottest year ever recorded—we saw a surge in heat-related illness, poor air quality, and storm-related displacement.
But it doesn’t stop there. Mental health is under siege. Eco-anxiety, depression, and trauma are on the rise, especially among youth. At the same time, we know that spending time in green spaces reduces stress hormones, lowers blood pressure, and improves overall well-being. It has a well documented physiological impact on our human health and well-being.
Even our food systems are vulnerable. Warmer temperatures and extreme weather reduce crop yields, disrupt global supply chains, and erode nutrition. As a result, food insecurity—and its downstream health effects—is increasing across the globe.
We are living in a time when environmental degradation is undermining every determinant of health and thus well-being.
Health Professionals: Our Most Trusted Messengers
The healthcare sector, in particular, has both a responsibility and an opportunity. It makes up nearly 18% of the U.S. economy and contributes about 9% of national greenhouse gas emissions. But doctors, nurses, hospitals, and health plans can lead the shift toward sustainability—and healthier outcomes.
Even more important, doctors and nurses are among the most trusted voices in society. When they speak up for clean air, safe water, and climate resilience, people listen. That’s why we need to equip tomorrow’s physicians with the knowledge to lead.
At Meharry Medical College, my wife Tracy and I recently launched a fellowship for students focused on Planetary and Human Health. These future leaders will explore how climate change affects chronic illness, infectious disease, mental health, food security, and healthcare infrastructure.
In short: healthcare needs to treat the planet like a patient. Diagnose what’s wrong. Prescribe what works. And bring the public along in the healing.
Nature-Based Solutions Work
Solutions already exist—and they improve health now.
Take neighboring Louisville, Kentucky. There, the Christina Lee Brown Envirome Institute, partnering with The Nature Conservancy and the NIH, studied how green neighborhoods affect heart health. The result? Simply living near trees lowered blood inflammation markers associated with heart attack and stroke. Just being near nature has changed people’s health. It’s proven.
We’ve seen similar benefits from regenerative agriculture, which Tracy and I practice on our farm in southwest Virginia. By planting trees, rotating livestock, and restoring wetlands, we improve soil health, store carbon, protect water, and grow more nutritious food. What’s good for the land turns out to be good for people, too.
At The Nature Conservancy under the leadership of our Chief Scientist Katharine Hayhoe, we established a new Planetary and Human Health Initiative to embed health outcomes into conservation work. The goal is to measure how efforts like reforestation, sustainable agriculture, and wetland protection directly improve human health—so policymakers, businesses, and communities can act with confidence.
A New Narrative—And a Call to Action
For too long, climate change and biodiversity loss have felt distant and abstract. Or politicized. Or overwhelming.
But health is personal. No one wants their child to develop asthma from polluted air or watch a loved one suffer from a heatwave. When we talk about health—not just polar bears or melting glaciers—we reach hearts and minds.
And most Americans are already on board. Nearly 70% recognize climate change as a serious concern. Over 90% support nature protection. What’s missing isn’t awareness—it’s activation.
Here is the new narrative. One rooted in science, focused on health, and powered by shared values. That’s how we build the broad, bipartisan support needed for real, lasting change.
Why I’m Hopeful
I’ve seen the power of science, innovation, and public will. I’ve seen society reduce smoking, control HIV, and slash traffic fatalities. These victories weren’t easy—but they were possible because people came together around shared goals.
We can do the same for climate and biodiversity. But we must speak plainly, act boldly, and lead with health.
Because in the end, this isn’t just about saving the planet. It’s about saving ourselves.
And the prescription is clear:
Protect nature. Invest in nature. Because nature is medicine.
The author serves as global board chair of The Nature Conservancy, the largest conservation organization in the world.