
How climate change harms human health — and what can be done
7/9/2026 | 26m 46sVideo has Closed Captions
How climate change harms human health
From air pollution to wildfires, from heat waves to vector-borne diseases, climate change harms our health and causes significant stress to our healthcare system. Horizons moderator William Brangham explores what can be done to protect people from a warming world with Victor Tsao of the U.S. National Academy of Medicine and Lisa Patel of fthe Medical Society Consortium on Climate and Health.
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Problems playing video? | Closed Captioning Feedback

How climate change harms human health — and what can be done
7/9/2026 | 26m 46sVideo has Closed Captions
From air pollution to wildfires, from heat waves to vector-borne diseases, climate change harms our health and causes significant stress to our healthcare system. Horizons moderator William Brangham explores what can be done to protect people from a warming world with Victor Tsao of the U.S. National Academy of Medicine and Lisa Patel of fthe Medical Society Consortium on Climate and Health.
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Learn Moreabout PBS online sponsorshipI'm William Brangham, and this is "Horizons," with a special episode from the Aspen Ideas Health Festival.
From air pollution to wildfires, from heat waves to vector-borne diseases, it's well known that climate change harms our health and causes significant stress to the nation's health care system.
And while doctors and clinicians devise new ways to protect people from a warming world, the medical establishment is also learning that its own practices contribute to that warming.
Climate change and health care, coming up next.
♪ Narrator: Support for "Horizons" has been provided by Steve and Marilyn Kerman and the Gordon and Betty Moore Foundation.
Additional support is provided by Friends of the News Hour.
♪ This program was made possible by contributions to your PBS station from viewers like you.
Thank you.
Here is William Brangham.
Brangham: Thank you all so much for joining us here today.
It's such a treat to be at the Aspen Ideas Festival.
And it is appropriate, I think, that we are talking about climate change today, especially in this location.
I mean, anyone who has been here in the summer looks up at the mountains at this time of year and sees snow that is still there.
That snow is no longer up there.
We know we are also in the middle of a tremendous drought here in the West.
I spoke with a man yesterday, a 55-year veteran of Aspen, and he said that he had never seen the river running quite so low.
We also have dozens of forest fires that are burning all over us surrounding this area right now.
These are all symptoms of climate change.
These are the flashing red warning signals that this is a real problem facing us.
We know that climate change also has a huge impact on human health.
And that's one of the things that we're going to be talking about today, the medical establishment's recognition of this as an issue and what it is doing to try to address that.
We're also going to be talking about how the healthcare industry is recognizing that, while it is trying to protect people from the impacts of climate change, it is also a major contributor.
The way in which we practice medicine in America is a contributor to climate change.
And there are ways to make that better.
So we're going to be talking about that as well.
And for that conversation, we have two perfect people for that.
At the far end here, Victor Dzau is the president of the U .S.
National Academy of Medicine and vice chair of the U.S.
National Research Council.
Previously, he was chair of medicine at both Harvard and Stanford Universities.
And Lisa Patel is the executive director of the Medical Society Consortium on Climate and Health.
She is also a clinical associate professor of pediatrics at Stanford University's School of Medicine.
Welcome to you both.
And thank you so much for being here.
Victor, I would like to start with you first.
Could you help us understand?
Was there a moment?
Was there a period of time when the medical industry started to recognize that climate change was a real problem, that it made us, humans, sick?
When did that happen?
How did that happen?
Well, I would say that, to begin with, you know, our community have looked at these issues of extreme heat, you know, extreme events as an environmental issue.
It wasn't until about... Because we've always taken care of patients with these issues, right?
Air pollution and respiratory disease, asthma, you name it.
But I think in the 1990s, the association between climate change and these events were very clear or getting increasingly clear.
So my feeling is the major leap forward is the last 15 years or so.
Brangham: Lisa, from your perspective, that sense, was there a moment, again, from your perspective, when did your community start to realize this is something we have to tackle directly?
Yeah.
And I came at this a little differently than Victor because I was actually an environmental scientist first.
And so I've been studying climate change for 30 years.
And then I became a physician.
And I remember thinking I would have some time to learn how to be a good doctor and be... My kids are in the front row, learn how to be a good mom.
The wildfires.
I live in Northern California.
The wildfires started to hit.
And I started looking around.
At the time, I had no leadership positions in climate change.
And I started to look around and try to find other physicians or nurses that were working in it.
And it wasn't readily visible to me.
I really credit the youth movement in 2018 and 2019 that really just brought everyone out.
What I noticed was that there was this huge momentum around that time.
I think between the youth movements and these crises that were getting worse, I call myself an unfortunate wildfires expert.
This isn't what I dreamt of being when I was a little girl.
But I was an environmental scientist and a pediatrician.
And we were seeing so many people trying to make sense of what wildfires meant for their health that this was an area that I became an expert in.
And I saw that happen in lots of different areas and fields.
Emergency medicine physicians becoming experts on extreme heat.
Infectious disease doctors becoming experts on how vector-borne illnesses are changing.
So to Victor's point, we started to see those impacts and the profession started to learn as we go to try to bring that awareness to the work that we need to do.
Dzau: Can I say one?
Brangham: Please.
Dzau: I think frequently we think about climate change at these events.
But truth of the matter is, people are dying from chronic disease, respiratory disease, cardiovascular disease, mental health, infectious disease, from air pollution, right?
From many other events, about 7 million people die a year globally from air pollution.
That's climate change.
So while we think about these dramatic events, which is so important, we talk some more about this, we need to remember that the real impact in climate change is on these issues of asthma, respiratory disease, elderly, all the stuff which are chronic diseases as well as acute diseases.
Brangham: I mean, I've heard from environmental and climate experts for years making this argument that even if you do not care about climate change or the glaciers or sea level rise, that simply tackling air pollution alone would be saving, as you're saying, millions of lives every single year in premature deaths.
Victor, I wonder, as someone from your position, was there any skepticism in the medical industry to acknowledging that this was a real issue?
Dzau: Honestly, not much.
I think it just became issue awareness.
Most of you were not aware this was an issue.
I think what's exciting, what Lisa said, is around 2017-18 is when people begin to realize this issue.
And a lot of people are working on it.
But it is until we organize ourselves as groups of people, organizations, to say, "We need to do something about this," which, by the way, is so important, the communication with the public is so important.
And I'm sure Lisa would talk about how we're training our doctors, nurses to be sure that they actually make patients aware of this issue, particularly when we see extreme events, but even chronic events such as this.
The issue in pushing back is going to be, how much work do I need to do?
Hospitals say, "Wait a minute, "I've got enough to worry about.
"Do you want me to measure one more thing?
"Do you want to do all those things?"
Brangham: Lisa, to Victor's point, if I was a young medical student today and I came out of medical school, or even compared to, say, 10 years ago, are doctors being trained to be focused on this, to be aware of this, to see those linkages that you're talking about?
Patel: Again, the credit I really want to give here is the youth movement and what we've seen in medical students.
I would say they have been really the soul of a lot of the work that we've seen happen.
And so around 2018-19, there was a group called Medical Students for a Sustainable Future.
They created a planetary health report card, and it has spread throughout the country.
And it's been a way for them to leverage to their medical school what their grades are in terms of teaching planetary health.
Now, are we as far as we need to be?
No.
But thanks to the work of these medical students, more and more medical schools are integrating planetary health into their curriculum.
Brangham: Is everyone saying, "Oh, of course this makes sense, "of course we need to start doing this," or is it a, "I don't have time for this, "I'm focused on board certification," all of those other things?
So I love Victor's optimism.
I have encountered something a little bit different.
Brangham: We have an optimist side, we have a pessimist side.
Patel: I call myself a cynical realist.
But what I've encountered in a lot of the talks that I do, especially in the community, is that there is a segment of the population in medicine that denies that it's happening.
Now it is the minority, and we know this from the polling research, it's about 10% of the country.
It does show up in medicine in different ways.
But the other thing that I hear, and I work in a small community hospital, we are dealing with a, if not breaking, if not broken, then breaking healthcare system.
I'm in pediatrics.
30% of beds in this country for children are gone.
Brangham: 30% of beds for children?
Patel: For children in hospitals, because community hospitals are closing their pediatric wards.
And so what happens, especially during high pressure times, like respiratory illness or big air pollution events, I have had to call to Nevada to get children transferred because there are no beds in the Bay Area.
This is the Bay Area, right?
And so healthcare already is under significant strain.
We have not recovered from the pandemic, and we are going to see more pressure from climate change.
So to your point, what I often hear from providers is, "Not one more thing.
"I cannot handle one more thing."
And this is where I think sustainable healthcare is actually a really good way in, because the way we talk about sustainable healthcare and what I have felt from healthcare providers is that it addresses moral distress.
It helps people have a sense of agency again, that your healthcare institution can be part of the solution of healing, rather than just feeling like you have no agency or control over the system.
I do think reaching healthcare workers front line, reaching the community health workers, reaching the non-MDs and nurses are key in being able to take that out to the community, because most of what we're dealing with, to my knowledge, again, is these chronic events, also heat events, in addition to extreme events.
Brangham: Yeah, I was just reading a study from Harvard that indicated that four out of five staff at frontline clinics, just as you're describing, reported climate-related disruptions to care.
And that could be power going out, staff shortages, facilities being closed, transport being disrupted.
I mean, it seems like the people who are on the front lines of this are starting to understand because they're seeing it happen all the time.
Patel: And I experienced at least two of those events.
The power got cut at our hospital, nine o'clock at night.
It was a high wind advisory, which is a big risk for fire.
PG&E just cut the power at our hospital with no notice.
And so we entered a blackout.
I work on the maternity ward, and so moms who had just delivered their babies were just walking around in the pitch black dark.
And this was a minor event, mind you.
My colleagues up in Santa Rosa, they had to actually evacuate their hospital because of oncoming flames that engulfed parts of that hospital.
Brangham: Victor, could you tell us, you were mentioning before some of the things that the National Academy is doing on this front.
Tell us a little bit more about that.
Yeah, I see this as a huge existential threat to our health, to be sure.
And I can give you numbers.
I already did.
Seven million deaths from air pollution, you name it, right?
So it's a real big issue.
One is, of course, looking at how to communicate to the public, right?
We have a lot of work to do.
And I think Lisa's right.
Publics have to understand, and they see the extreme events more visibly and respond to it.
But we need to communicate to the public.
Second, of course, is looking at what the health sector should be doing, resilience.
How do we create a health sector that is ready, prepared for emergency, as well as long-term, efficient?
Brangham: That doesn't have a blackout, like Lisa's describing.
Dzau: And how do we work with communities to help them be more resilient, right?
Third, of course, is research innovation.
What kind of research innovation do we need to do?
We published a whole report on what are the future areas of research innovation needed with Kaiser Permanente, and that was looking at communities.
We have a program that actually looks at communities.
We look at what are the map, all the counties in the country, looking at what are the communities with the highest risk.
They're usually the highest risk in terms of the kind of extreme events, but also socioeconomic risk, marginalized community.
And then finally, we're doing what they call systems transformation, getting together other industry, agriculture, transportation, construction, energy, you name it, to say, "Can we work together and policy "to put health in the middle of all those things?"
So it's a big initiative.
Brangham: Lisa, do you think that some of the... I don't want to point fingers here, but the slowness of our societal response has been in part because the people who suffer the most from the impacts of climate change are not the people in power, the people who are wealthy are able to shield themselves in some way.
Do you think that that has contributed to some of this?
Patel: I mean, I think it's two things.
I think that the fossil fuel industry, who's known since 1960 with great accuracy, exactly the problem that would happen.
Rather than start making those investments then to give us a thoughtful time and a thoughtful transition to renewable energy, they sowed mass disinformation, mass denial, paid off politicians to look the other way while we continued investing in fossil fuels at the expense of renewables.
So we can't talk about this crisis without talking about the role of the fossil fuel industry.
And what frankly makes me upset is that now we are in the midst of dealing with these types of extreme events where this is not, I run codes on children, that the time to prepare for a code is not in the middle of a code, the time to prepare for a code is well before it.
Brangham: A code is an emergency declaration of a... Patel: So if a child comes in at death's door or essentially dead, same as an adult, right?
Everybody comes in and you're resuscitating that child or you're resuscitating that adult.
And so that is not the moment when you figure out what needs to happen.
You need to do that well ahead of time.
And so what I feel anger about, especially on behalf of my kids, 60 years we had, 60 years to get this right, and now we are in the midst of dealing with crisis after crisis where we're going to have to figure all of this out at the same time.
But the second point you raise is true.
And I've seen this play out in the Bay Area on very hot days, very smoky days.
My children are in San Francisco Unified School District where the schools were built for a Mediterranean climate.
They don't have HVAC systems, they don't have air conditioning.
And meanwhile, the private schools in that same area are completely buffered from all of these impacts.
So yes, if you have... Air filtration, air conditioning, greener spaces that they have access to.
So absolutely what the climate change crisis is, is a crisis of health equity of the haves and the have-nots and the systemic disinvestment in basic infrastructure.
Whether we are talking about a working sewage system, I was speaking in Baltimore and they had flood events driven by climate change that broke some of the sewage systems in disadvantaged neighborhoods.
Feces were backing up in their bathtubs and their sinks, for example.
And so this is where we are.
We've created a system where some people have the money to stay safe, the majority of this population does not.
And we are now in real time seeing those consequences play out.
Dzau: I totally agree with her.
I always said that, if you talk about health equity, it's a social equity issue, right?
And this is one example.
But this is why these stories are so important, because people see climate as something happening here, happening there, they don't realize it's happening to their health.
Brangham: There was a recent gathering of former health and climate ministers in Europe, and they got together and they were urging the World Health Organization to declare climate change a public health emergency on the scale of monkey pox or Ebola or COVID.
Do you think that that kind of international alarm signaling would be useful, Lisa?
Patel: I would have said yes once upon a time.
I guess what I... Brangham: See, this is back to being the pessimist side.
Patel: It's more than I think.
There's just signal fatigue across society.
There are so many.
And I've also seen how the Trump administration has used emergency declarations for fairly perverse purposes.
And so I don't know that I think it's the powerful tool that it once used to be for a number of reasons.
And so I wouldn't be against it, but I also wouldn't rely upon it as the answer, the solution to mobilize the resources that we need.
Brangham: It doesn't feel like a lever that will actually galvanize meaningful action.
Patel: Not to me, and not in this particular moment.
If you'd asked me the same question five years ago, I would have given you a different answer.
Dzau: I'm a slight optimist in this one.
First of all, our country notwithstanding, there is a big global movement.
I do think it matters because when people with a high enough priority, just like everything else, you need to at least make commitments and action.
For example, every country have a climate national plan.
They need to incorporate health into a climate national plan.
So those plans do exist.
You put climate in there.
So actually, I do think this makes a difference, even though she doesn't feel the same way because where we are living in our country.
But I do think internationally, there's a movement out there that's recognizing this as an existential threat.
There's no question about this.
Brangham: I do want to pivot back to what you were mentioning before, Victor, which is this understanding by the healthcare industry that in and of itself, even as you are doing all of these things to try to help people, the healthcare industry is not the most efficient in the world.
I think anyone that has been in a hospital or a medical setting understands that there is an enormous amount of waste.
The lights are on all the time.
The air conditioning is running constantly.
Lisa, does that strike you as, again, another fertile ground for trying to move the needle in a meaningful way?
Patel: Well, I want to build on something that Victor has said a number of times.
Yes, the air conditioning and the lights and all that.
But the bigger issue is that of all the chronic disease and the burden of that on our country and our health systems, we live in a sick system.
We do not live in a well system.
In a sick system, where what we're constantly coming up with is new therapeutics, new drugs to treat whatever new diseases are coming along, we generate more waste in the process if only a pound, an ounce of prevention is worth a pound of cure.
If only we as a country would actually invest in prevention, that to me is the climate solution for healthcare, is that what we want is we want a healthy population that doesn't have to access this much healthcare to begin with.
That is the far better solution to this problem.
And yes, there are other things that we can do around facilities that feel more tangible to folks.
But that to me will be a drop in the bucket.
As Victor was mentioning, 80% of our emissions, it doesn't come from the facilities itself.
It comes from all the products that we are constantly producing to treat an unhealthy population.
That's where we need to invest our energy.
Brangham: If you simply bring the disease burden down broadly, we'll be doing less of this inefficient stuff.
Patel: Correct.
Brangham: I mean, it is, to what you were saying before, Victor, that it is, I can't remember the exact percentage of America's greenhouse gas emissions, but it's a not insignificant amount.
I mean, I think it's more than all the airplane flying that we do all over the country.
Dzau: 8.5%.
Brangham: I mean, that is, if you carved American healthcare out into its own nation, that would be an enormous polluter that we would be jumping all over to try to do something about.
Dzau: I think for healthcare, health sector, globally, it's 5%.
It ranks among the top five countries, I think, in emission.
Patel: We are a sick system.
Dzau: Yeah.
That's why I say collective work globally is important.
It's not just US, it's everywhere, right?
That's why those things do, I think they do matter in trying to work together in that direction.
Lisa, on this issue of trying to make a system more efficient, you are a practicing doctor.
If your administrator came to you and said, "We would like to do this more efficiently, "and we think it could be done XYZ way," do you think that there would be pushback?
Maybe not you, you clearly understand the rationale for this, but as we were saying before, doctors have so much on their plate already.
Does it feel like it's one more thing that your colleagues, writ large, don't want to deal with?
Patel: I am very proud for the healthcare system where I'm at.
I'm at Stanford Healthcare, and actually, I just spoke with our sustainability director before I came here to talk about what our journey has been, to your point that, yes, we have a lot on our plates, but also doctors, nurses, those of us that work in the hospital systems, we are powerful voices for change.
In 2020, we got together with some students that were really distressed about climate change.
We put together a symposium.
Our CEO came, along with other CEOs in the region, and it turned into this race to the top of who could do the best.
Six years later, I was getting all these messages from CleanMed, which is this big conference for healthcare sustainability, that our CEO was on the stage telling everyone else, "Talk to your CEOs, talk about climate change.
"This is important."
Brangham: That's how change happens.
Patel: That's how change happens, and especially because, to this point, there's massive healthcare worker burnout right now, but what I have seen in healthcare sustainability is that it is the remedy to burnout because it is mission aligned with what we as healthcare workers want to do, which is to take care, to take care of people, to take care of planet.
It really re-infuses with a sense of purpose.
This is like a fairy tale, right?
This doesn't happen everywhere, but what I have seen time and again from other nurses and doctors that I've seen in other healthcare systems is that it starts with them.
You do need some buy-in from the leadership at the top to really get somewhere because the number one way to go nowhere is that you're just kind of toiling along in your system and you can't get anybody on board with you, but persistence also matters.
What I've seen is where people are successful is where they keep at it, more people come into it, you have a conversation with leadership, but you kind of need both of those pieces.
You need people within the system that care and you need leadership buy-in, but it is possible and we are seeing more and more healthcare systems step up to do it.
Brangham: Thank you all for being here.
That's it for this episode of "Horizons."
Thank you so much for watching.
We'll see you next week.
Narrator: Support for "Horizons" has been provided by Steve and Marilyn Kerman and the Gordon and Betty Moore Foundation.
Additional support is provided by Friends of the News Hour.
♪ This program was made possible by contributions to your PBS station from viewers like you.
Thank you.
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