Climate Action
Climate Change in Our Bodies and Our Communities: 22 Minutes with Dr. Carlos Faerron Guzmán
April 17, 2026
Where human and environmental health intersect, Dr. Carlos A. Faerron Guzmán offers a perspective that goes beyond hospitals and medical treatment: planetary health.
In his discussion with an EARTHDAY.ORG educator Dennis Nolasco, Dr. Guzmán reflects on practical experience from his work as a physician in an Indigenous community in southern Costa Rica, highlighting how closely human health depends on the surrounding environment.
Set within the broader discussion of the Earth Week 2026, his message focuses on the idea that environmental conditions and human health are deeply connected. Dr. Guzmán argues that problems such as respiratory illness, extreme heat, limited access to nutritious food, infectious disease, and emotional stress should not be viewed in isolation from climate disruption. Rather than treating these issues as separate topics, Dr. Guzmán presents them as part of a larger system in which damage to air, water, land, and local environments directly affects people’s lives.
Dr. Carlos A. Faerron Guzmán is an international scholar and educator in global health whose work focuses on equality in healthcare. His teaching and research reflect a strong interest in how social and environmental conditions work together to shape well-being across communities. He holds leadership and academic roles at University of Maryland Baltimore, John Hopkins University, the InterAmerican Center for Global Health, the School of Professional Studies at Northwestern University, and the Universitat Oberta de Catalunya.
Earthday.org’s 2026 theme, Our Power Our Planet, reflects how actions we take now can save us the invisible costs of climate change in the future. Our health starts with our environment, and we have the power to keep that environment clean and thriving.
Q: Carlos, welcome. You’ve worked on the frontlines where health and environment intersect. Was there a moment or experience that made you realize the planet’s health and human health can’t be separated?
I’ll say there was kind of a slow movement towards that recognition. Early on in my career as a physician working in an indigenous territory in southern Costa Rica I started understanding how these interconnections of health and the environment happened. I grew up mostly as a, let’s say, a city person. I didn’t fully understand out of lack of lived experience and somewhat ignorance how directly the environment actually shapes health, food, daily life and even things like our spirituality. So what I saw in that indigenous territory was that the environment was not something that was a backdrop to health, it was more or less the foundation of health.
A lot of times in urban life. It’s easy to think that health is managed in clinics. In that indigenous territory called La Casona It became very clear to me that actually health begins much, much earlier. In the land, in the soil, in the water, in the food systems and in the ecosystem — the other living beings that are surrounding us — and that experience really exposed that this way of understanding health from a very urban perspective is very very limited.
I say that cured me from that urban illusion. So when you see that food comes directly from the soil that you’re surrounded by, when you’re seeing that your health depends right on the water that’s in the river, and that even the identity of people are so tied to place. The idea that environmental degradation is separate from health really becomes very difficult to defend.
Q: For those hearing “Planetary Health” for the first time, how would you explain it in a way that connects to someone’s daily life? For example, what’s a simple way to see this link while walking through a city or sitting in a doctor’s office?
Planetary health is a simple idea. We can have layers of our understanding, but the simplest way to explain it is that the health of humans depends on the stability of the natural systems that support our well-being. The simplest way that we interact with natural systems is the air we breathe, the water we drink, the soil where our food comes from, the climate that helps us live stably, so to speak. The ecosystems, the bees and the other aspects of living things that live with us. If those systems are degraded, then our health is deeply affected.
And whether you notice that immediately or not, those things are interconnected. So let’s say I’m gonna use an example from a normal city block anywhere in the world, and in that city block you can have things like excessive heat trapped in concrete. You can have pollution of the air coming from traffic. You can have little presence of greenery that provides little shade, creating a hotter environment. You’re seeing that in the neighborhoods that flood quite easily after heavy and extreme rains. You can even see it when you go to the supermarket. The quality of the food that we buy. Right? So in our daily lives, we’re encountering these ways in which natural systems degradation is starting to impact our health.
We as physicians, we’re also seeing this at the end of the process. We see more cases of asthma, more cases of heat stress, more cases of anxiety, more cases of infectious diseases, more cases of malnutrition because people are struggling to access healthy food.
And these are not separate problems. These are all interconnected through what we call global environmental change. So planetary health should not be thought about as an abstract environmental issue. It’s really about whether we can thrive breathing clean air or drinking safe water. And in general, just supporting those living conditions that support our health and the health of the other species that live with us.
This is why we call it planetary. Our planet Earth shows up in the conditions of our bodies. And that is because science keeps telling us this more and more. Everything is interconnected.
Q: Where do you see climate change already showing up in people’s bodies or communities today — even in ways that aren’t labeled “climate-related”?
One thing I’ll say when we talk about planetary health, right, we’re not just talking about climate change. We’re talking about “everything” change, so to speak. We have huge changes in our biodiversity. We have huge changes in the quality of our soils. We have huge changes in the quality of our air, in the quality of our water.
We see changes happening at every single natural system that we know. And climate change is definitely one of those very prevalent symptoms of our larger syndrome. But I think one of the biggest misunderstandings is that climate change is a future problem.
It’s actually very visible in everyday health and in every person around the world. You see it in everything from worsening respiratory diseases and that changing towards not just someone that has asthma but has a more severe case of asthma, not someone that has chronic obstructive pulmonary disease, but has a more severe case of chronic obstructive pulmonary disease.
Right. Because in a sense, right, the world is becoming hotter, becoming more polluted, and it’s making it harder for people to just get their daily necessities of clean air, clean water, good food, being met.
I think even today, as we’re seeing it, due to ongoing geopolitical aspects and conflicts, we see it in our food systems. We see higher prices, we see reduced access.
And as changes in temperature and rainfall patterns really start being unpredictable, it affects what we call vector borne diseases like mosquitoes, and we see rising cases of things like dengue. And the numbers tell us if we don’t start changing the way we look at these challenges, these challenges are only going to get worse.
So climate change is already showing up in people’s lungs, people’s diets, people’s stress level, and every single choice they make in their daily lives. This is not something of the future.
This is something that’s happening right now.
Q: You co-authored a recent Annual Reviews piece on Planetary Health: Focusing on the Intersection of Human Health and the Earth System. Which findings struck you most personally — something that surprised you or changed how you think about health care itself?
I’ll say the central message of that piece is that the Earth crisis is fueling a global health crisis.
And those things cannot be separated and understood in different policy realms or solution realms. They need to be seen as one and be tackled as one. And part of what we talk about in that paper is the transgression of what we’re now calling planetary boundaries, which are these limits which the best science deems is a safe living space for the majority of humanity.
So that’s what we call the concept of planetary boundaries. Anything above a planetary boundary is deemed unsafe for humans. So you think: how much climate change before it becomes unsafe? How much pollution before it becomes unsafe? How much biodiversity loss before it becomes unsafe?
So the most recent assessment of the boundaries tells us that six out of the nine boundaries have already been transgressed to dangerous levels, which means that we are already operating outside much of the safe space and that human society is at high risk.
And we’re seeing that in everything from coastal Bangladesh to central Texas to the Amazon. We’re seeing it all over manifesting in different ways as a manifestation of the Earth crisis. And one of the things that in the paper we really emphasize is that the data keeps showing that health is often harmed before there’s actually a transgression of the boundary.
Especially health is mostly harmed in vulnerable communities. So there are communities already that are starting to pay the price of this Earth’s crisis very early. And these are communities all around the world.
And that challenges us to think that we shouldn’t wait until everything is color red and the alarms are ringing. Which is kind of what the Planetary Boundaries framework kind of depicts.
Q: Are you seeing momentum within the medical field toward viewing environmental protection as part of health care itself? What would help accelerate that shift?
Yeah, I’ll say there is momentum, but I’ll say also that the momentum is quite uneven and that it’s slower than what we want and what science would justify. So there is growing awareness, I’ll say that. There are more people around the world that are recognizing how the environment is interconnected with our health.
But that recognition is not necessarily leading to institutional change or systemic change. So that is still, let’s say, lagging a bit. And we still see that health systems around the world and education systems around the world are still treating the environment factor as kind of secondary rather than a core determinant of health. And this is a structural problem that we know is about training, it’s about finance, about governance.
And those are still organized in a kind of an old way where we’re treating illness rather than preventing it or promoting a healthier environment. So we need to change both in our imagination, how we do these things right and how we actually act. So we think at the Planetary Health Alliance that accelerating this shift means integrating planetary health into education, changing incentives, recognizing environmental risk as a clinical reality.
So we have training modules for clinicians and public health professionals that want to understand how do we actually go about doing this.
And then there’s another aspect of planetary health that’s interesting around the medical field and health system, which is looking inwards, so to speak, and saying, “What’s my role in, you know, the environmental issues? How am I disposing my waste?”
There are countries where the footprint of a health system can be anywhere between 5 to 10% of the environmental footprint from that country.
So it’s not minor that we ourselves, from the health systems, the health professionals are part of the problem. And we could be doing more in that sense. So there’s kind of many ways or many paths that can lead to convergent solutions towards reaching that momentum that you were mentioning earlier.
And as I said earlier, part of the challenge is how do we distribute this momentum where it is mostly needed. Because right now there’s a handful of countries that are trying to advance this of university systems, of health systems, of policy and decision makers and many other actors that are trying to move forward. But we really need convergent actions.
And then because priorities are shifting in other parts of the world due to geopolitical, political circumstances and, you know, lobbying and many other things, then we see that momentum lagging or even, you know, struggling to pick up. So it’s unfortunate, but in the Planetary Health Alliance, I’ll say we’ve captured a lot of that momentum and we try to systematize it in order to be inspirational to others.
Q: You’ve argued that climate action is one of the most cost-effective public health investments. What does a prevention-focused health system look like in practice — and what would it take to move from treating illness to preventing it at scale?
In a lot of my classes, I usually tell my students when we think about prevention in health systems, we think about it too narrowly.
Our own definition of health is too narrow. And because our definition of health is narrow, then our actions are narrow. So we think about prevention and health systems on things like screenings and vaccines. But actually prevention is much more than that. It’s also about those very basic things like air, water, good housing, stable food availability, and the quality of that food.
Right. So securing all those aspects should also be part of what we understand as a preventative health system. So a preventative health system should not be thinking about things downstream. Yes it should, but we also should be looking at the upstream conditions as part of when we think about goals involved in health policy, not just external environmental issues.
When we think about, you know, a planetary-health-friendly health system. It’s more around a priority problem. And we really need to start getting our priorities straight as societies, as voters, as professionals of healthcare or professionals in education. In general the world really needs to start thinking about what it is that we want to do and what kind of future we want to create.
And I think one way to look at this is through one specific lens, which is climate action. It’s a very powerful health investment. It produces not just benefits for us today, but benefits for the people in the future. And all aspects of our health and our well-being will be improved through climate action.
I recently saw a cartoon that says, “What if we created a better world for nothing? And climate change was just a hoax?” If you think about it, it is like we could be creating a better world just because. Even if there was no climate change.
Climate change exists and it’s very real, but what’s stopping us from creating a better world? So I think, again, priorities need to be set out straight. This relates to people’s values, relates to constitutional values and many other things that I talked about a lot in my classes.
Q: You’ve said education is your passion. What’s one way we can better connect with people who don’t see climate change as personal yet — to make them realize it’s about their kids’ asthma, their food, their mental health?
There’s no one way. And if we had the one best way, we would be repeating and repeating and rinse and repeat.
But different parts of society, different geographies will react to different things. And I think understanding that is a good place to start. Now there is science that is telling us what type of messages tend to hit best with certain parts of communities and societies and professions. So even looking at that science is a good starting point.
But for the most, I think, we’re starting a lot of the time in the wrong place. We—and I might be even at fault at this at times—We start with abstract language, instead of things like lived experience.
So we start seeing climate change as personal. Not as global averages, but daily lives. As you were saying, impacting people’s asthma, the cost of food, the heat, the stress, the sleep. But even if you do that, there’s going to be a part of society that thinks that’s immune to that, right? Whether because they have strong social networks or they have high resources or simply they’re, you know, not empathetic.
And that’s where I think appealing to people’s values and common sense and common good is important. So, we need to bring it down to people’s personal lives. But still we know that more information is not always gonna lead people to change.
Education, as we traditionally think about—and you’re an educator, so you know what I’m talking about—Education is not about putting more information in people’s brains. It’s not just about giving more information, new information. It’s also about how we look at stuff. How we frame the challenges, how we frame that solution.
So kind of boiling it down to everyday climate and health connections, it’s about not just telling you these are the impacts, but reframing what actually counts as health issues. So how does this affect their body? How does this affect their family? How does this affect their communities? How does this affect the overall long term well-being of a country?
And we might start seeing that when that happens the conversation might change. So in Costa Rica, for example, we see this in Latin America in general. We start seeing people from all around the spectrum starting to recognize how, you know, the heavy rains, the dengue, the food insecurity—all these things are now made more explicit in the way we communicate them.
And asking people to reframe this is not just impacting a sector of society. It’s impacting the country as a whole. It’s impacting global as a whole. And we need to start thinking about solutions together. So the goal is to make climate change visible, not something that is abstract, not something that is distant. It’s bringing it to people’s day-to-day lives, but also bringing it to the things that they care about the most.
Q: You’ve spoken about how pollution shifts costs onto families and health systems. Can you walk us through an example of that “invisible bill” we’re all paying — and why prevention could actually save money and suffering alike?
Invisible bill is a good term because it tells us about the costs that we’re not seeing. When we pay for gas at the pump, when we pay for plastic in a supermarket, we’re not paying for the real cost of that.
There’s, you know, externalities that go into that production process to get from under the Earth to that gas pump that are not necessarily easily seen. and this is why the invisible bill is a good concept.
So I’m going to go back to perhaps the example of the kid with asthma that’s exposed to polluted air from traffic or industry or the production of dirty energy. And that kid is developing asthma and having to visit the E.R. every now and then to get treatment and starts having issues to thrive because of this asthma and can’t control their asthma.
So there’s, you know, the price we pay in the pump or the price we pay for energy. But there’s also kind of the invisible bill, as you were saying, which is the family that is paying for the medications, the clinical visits. How about that kid missing school and what that means for that kid’s life? How do we put a cost on that? How about future missing work or all the stress that is causing not just to the kid, but also the family?
And then there’s the health system. The health system is paying through emergency visits, long term care, increased demand, worker burnout. And all that is caused by us and air pollution or the way we produce our energy. The entity that is responsible for the pollution is not really paying for the damage.
And obviously this is one example, but it’s not limited to just asthma. It also applies to polluted water, heat-related illnesses, and food system impacts.
Um so we often say “profits are concentrated, but the damage is distributed.”
Q: Fixing “the air and water” can’t fall on individuals alone. What’s one bold move you’d like to see from governments, businesses, and health systems to anchor prevention in policy — not just personal choice?
Well, I don’t know if it’s bold but it seems rational. I’ll say that I’d like to see more rational decisions being taken. And one of the decisions or rational moves that we could take is apply a concept that’s been part of how we think about these challenges for a while in all policy frameworks.
Now we’re looking at planetary health in our policy. And that really means that all major decisions that countries and societies make—be it energy, economy, transport, housing, food—that the decisions aren’t made until we have clarity on what will be the impact on people’s wellbeing now and into the future.
So I don’t know if that’s bold, but I think that’s rational, right? Health shouldn’t be an afterthought. It should be the central metric of whatever we do in policy. And there are frameworks to look at. And these are already being applied in certain parts of the world.
For our government it means embedding health into planning, into budgeting into regulation. But it also can apply for other stakeholders like businesses.
For businesses, it would mean recognizing that shifting a cost to society is unacceptable. That’s a value decision. And I think that decision needs to be made. But it also can be a carrot and stick, right? So governments can play a role in how businesses make those decisions, right? For families or for health systems, for example, that shifting means using the influence, right, and their knowledge and their accumulated trust, and that form of power that is not just economic, but health system has a lot of power in the form of influence and moral and knowledge and data, of course, that can advocate for this approach.
Q: If we reimagined health care as prevention on a planetary scale, what would that system look like? How would it feel different from today’s model?
So, if we were to design a planetary health intervention that can trickle down or go from bottom up and spread around the world, the world would look different, right? I mean, the system wouldn’t be organized as reactive. It wouldn’t wait until damages were caused to react. It would immediately start shaping the things that I’ve been mentioning. You know, how we organize cities, how we produce food, how we produce environment, or how we produce energy, how we treat the environment, right?
People would start experiencing health and well-being in a much different way. They would experience it in the walk in the park with the cleaner air. They would walk through safer neighborhoods. They would have more safe, stable conditions and predictable conditions to make better life decisions.
So the measure wouldn’t be things like how many people I treat or how successful were those treatments, but how many people I’m keeping on the healthy side, how well is the planet doing? How many diseases am I preventing? There would be different metrics there that will help us. Tell us if we’re being successful.
And today, the end stage parts of systems, like hospitals, are carrying the burden. In this planetary-health-forward world we would still need hospitals, of course, but they wouldn’t carry the burden. The burden would be distributed much more in the other systems that keep us well.
Q: As Earth Day 2026 approaches, what gives you hope?
One thing that keeps giving me hope over and over again is that when I look at what’s happening around the world, it’s that we know probably 90% of the solutions that we need to implement.
There’s clear strategies being created. There’s clear technology, there’s clear governance schemes, there’s clear policy packages. They’re clear metrics. We know that most of these things work. And we know what that looks like. We can imagine ourselves in that world of cleaner energy, better food systems, healthier cities, stronger preventative public health systems.
We’re not navigating in the dark, but there are definitely forces pushing against that. But, what I do admire for the people working in the frontlines is their consistent push forward that also gives me hope.
And thinking about it from a public health side, as a public health person myself, just thinking about these things as we’ve been saying, the interconnectivity of how one thing that moves forward can then have a trickle down effect on how other things happen. How just secure and safe water can have, you know, immense, immense consequences for good for the people that are accessing that safe water.
The same goes for food. With better quality of the food, with better access to food, people’s lives will get better, not just now, but into the future. To think about that baby in a womb, getting nutritious food and the life trajectory of that baby suddenly improves exponentially. So that gives me hope as well, that there are kind of lock on effects that we can have down the line that we know are possible.
And I think kind of the question now is how do we actually act on what we already know? And from the Planetary Health Alliance, we’ve been working hard with different sectors of society and stakeholders to try to see what is that best “how.” How do we take that knowledge that we’ve created, those technologies, those governance schemes, those policy packages, those behavioral changes, you know, those solutions from all sides and how do we best implement them? Because I think the alliance is in itself pushing forward and trying to find those convergent actors in order to do that more quickly and create that shift that we need.