Dr. Gaurab Basu
Assistant Professor, Brigham and Women's Hospital and Harvard Medical School
May 12, 2026
Dr. Gaurab Basu is a primary care doctor in Boston and a global health physician who has worked in India, Liberia, and elsewhere for years. He teaches at Harvard Medical School and the Harvard T.H. Chan School of Public Health, where he sits on the faculty of the Center for Climate, Health, and the Global Environment and the FXB Center for Health and Human Rights. He also serves as senior advisor for the climate and health program at the Child in Need Institute in India, and co-leads a Wellcome Trust funded project on the health benefits of climate mitigation policies in India. He talks about his own awakening to climate change as a thunderbolt moment in October 2018, after reading coverage of the IPCC report on an early Sunday morning. His wife was pregnant. The work he had been doing on health and equity suddenly looked different, and he reorganized his career to put climate change at the center of it.
Climate change is reshaping health in cities through heat, air pollution, infectious disease, and the disruption of healthcare itself. Around 500,000 heat related deaths occur each year, and roughly 37 percent of those are attributable to climate change. Air pollution is the bigger killer, with more than eight million deaths a year and five million tied to fossil fuel combustion. Most of that burden falls on low and middle income countries.
The urban story is not just about temperature. It is about which neighborhoods can dissipate heat and which cannot, which homes leak nitrogen dioxide from gas stoves into the lungs of children, and which communities historically lost the investment that would have given them tree canopy and green space. Heat does not stay in one organ system. It shows up as renal failure in young farmers, as mental health crises in emergency rooms, as gun violence in cities, and as premature birth and stillbirth, with disproportionate harm to Black mothers and infants.
Clinicians have a role beyond the exam room. Medical education, hospital operations, and the way doctors take a social history all need to change. Trees become a cardiovascular intervention. A 30 percent increase in urban tree cover can drop city temperatures by 1.3 degrees Celsius and prevent a third of heat related deaths. Doctors are a trusted voice across the political spectrum, and translating climate change into the health of people's families and neighbors is one of the most effective forms of communication available.
Heat is the most important climate to health mechanism in a city like Boston. When heat enters the body, the body tries to compensate. The heart pumps faster, blood shifts toward the skin, and sweat carries heat away. That is the compensated zone, where the core temperature stays roughly stable. The uncompensated zone is what breaks people.
Once core temperature rises and the body can no longer dump heat, enzymes denature, cells die, inflammatory cascades fire, and tissues lose integrity. The result ranges from cardiac arrhythmias and heart attacks to muscle cramping, kidney injury, liver damage, and at the extreme end, heat stroke. The people most at risk are the very young and the very old, pregnant patients, people with diabetes or heart or respiratory disease, people on medications that interfere with sweating, people who are isolated or cognitively impaired, and people who cannot leave the heat because of their job, their housing, or their disability.
The case that shaped Dr. Basu's thinking was a 30 year old farmer from Central America who arrived with cold symptoms, shortness of breath, and headaches. His labs came back showing end stage renal disease in a young, otherwise healthy man with no diabetes and no high blood pressure. The diagnosis was chronic kidney disease of unknown origin, also called Mesoamerican nephropathy, a heat triggered renal disease described in a New England Journal of Medicine piece. Years of outdoor labor in severe heat had left him chronically dehydrated, with reduced blood flow to his kidneys, until they failed.
The pattern is not unique to Central America. Sri Lanka has its own cluster. And the same logic now follows patients in Boston who work in construction, landscaping, factories, or any job that keeps them outside on the hottest days. Heat also pushes mental health into crisis. A 2022 JAMA Psychiatry study led by Amruta Nori-Sarma found significant increases in emergency room visits for mood disorders, schizophrenia, delusional disease, suicidality, self harm, substance use, and anxiety on very hot days. A separate study across 100 US cities by Jonathan Jay at Boston University tied hot days to increases in gun violence, with nearly 7 percent of shootings attributable to above average daily temperatures, and a follow up showed that neighborhoods with more tree cover had fewer shootings. A 2020 JAMA Network Open meta-analysis found that air pollution and heat exposure are associated with preterm birth, low birth weight, and stillbirth, with Black mothers disproportionately affected.
Takeaway Heat is not a single organ story. It is a whole body stressor that lands hardest on people who cannot escape it, and the clinical picture often looks nothing like a textbook case of heat stroke.
Two neighborhoods sitting next to each other can experience the same hot day very differently. The reason is the urban heat island effect. Asphalt, concrete, and cement absorb and reradiate heat. A neighborhood with no tree canopy can run 5 to 10 degrees Fahrenheit hotter than a leafy one a few miles away.
A picture of Chelsea, Massachusetts, a predominantly immigrant community with very little greenery, made the point. Heat bounces off the ground there with nothing to soften it. A map of historical redlining in Boston tracks closely to that pattern. Communities that were redlined in the 1930s, mostly communities of color and lower income communities, lost out on mortgages, public investment, and the green infrastructure that came with it. Studies have shown those redlined communities run up to 2.6 degrees Celsius hotter than non redlined neighborhoods today. The Lancet Countdown series adds that redlined communities also sit closer to more oil and gas wells and higher levels of air pollution.
A Lancet study on European cities found that increasing tree cover by 30 percent could reduce urban temperatures by 1.3 degrees Celsius and prevent roughly a third of heat related deaths. That framing matters in a clinic. Trees are not landscape decoration. They are an intervention against cardiovascular disease, respiratory disease, and premature death. Teaching that shift to medical residents is part of the curriculum work happening at Harvard.
Takeaway The map of hot neighborhoods is the map of historical disinvestment. Tree canopy and green space are public health infrastructure, and adding them is one of the more powerful preventive interventions a city can make.
Air pollution is the larger health threat. More than eight million deaths a year are linked to air pollution, with five million tied to burning fossil fuels, and the vast majority of those deaths fall on low and middle income countries. The home is supposed to be the safe place. With a gas stove in the kitchen, it often is not.
Decades of research connect nitrogen dioxide from gas combustion to respiratory disease in children, and new studies are extending that picture into cardiovascular impacts, increased allergens, and cognitive effects. Research out of Harvard and Stanford has shown that benzene, a known carcinogen, leaks from gas stoves even when they are off. With a stove running for 45 minutes, benzene exposure can be comparable to secondhand smoke. The stove also leaks methane, which is harmful to the climate.
No one needs to panic if they currently cook on gas. Opening windows, using a hood, and ventilating the kitchen all help. The longer arc points toward induction. In India, the surge in gas prices tied to the Middle East conflict has driven a wave of induction stove uptake, a useful reminder that affordability and health and climate gains can line up when communicated clearly.
Takeaway A gas stove is a small fossil fuel plant inside the home. The harms are measurable now, and the path away from them is already opening up where induction becomes affordable.
Climate change does not cause specific infections, but it changes where and when they appear. Mosquitoes prefer particular temperature ranges, and as those ranges move, so do the diseases the mosquitoes carry. Lyme disease has exploded in part because of warmer winters and because people now live in spaces that used to be forest.
Stopping deforestation matters in the same conversation. Forests are carbon sinks, but they are also buffers against pandemics. Hundreds of viruses sit out in nature with no clinical relevance, until people move into spaces that bring them into contact with human populations. Leaving more of nature alone is one of the more underdiscussed public health interventions of the decade.
Takeaway Clinicians need a practice, not a fact sheet. The diseases their patients will see are shifting, and the right habit is to keep surveilling what is changing locally rather than memorizing the map as it stands today.
The climate also disrupts how care gets delivered. After Hurricane Maria in Puerto Rico, a major share of households reported being unable to refill medications, access medical equipment, reach a hospital, or find an available doctor. Roads were damaged, healthcare facilities were closed, and the supply chain for routine care collapsed for weeks.
Heat waves stress the grid, and hospitals run on the grid. Patients on dialysis or chemotherapy cannot pause their care during a flood. Patients who depend on home medical equipment lose it during outages. Disaster planning, backup power, and proactive outreach to vulnerable patients are no longer optional capacity for a healthcare system. They are core operations.
Hospitals are also part of the problem. About 8.5 percent of US emissions come from the healthcare system itself. A growing number of medical centers, including Boston Medical Center and Brigham and Women's, now have medical directors of sustainability auditing the anesthetics on the shelves, the single use supplies, the waste streams, and the energy footprint. Some of those choices are pure waste with no clinical benefit. Some are real tradeoffs between patient outcomes and emissions. The work is to sort one from the other and bring the relevant specialists to the table to lead the change in their own departments.
Takeaway Extreme weather is not just an exposure for patients. It is an operational threat to the system that treats them, and the system contributes significantly to the emissions driving the threat in the first place.
In the clinic, climate aware medicine starts with a richer social history. Where does the patient work, and is it outdoors? Do they have an air conditioner or a heat pump at home? Do they live next to a freeway with chronic air pollution that is silently driving asthma? Are they isolated, elderly, on medications that block sweating? Are their children in a school that overheats and posts lower test scores and more behavioral incidents on the hottest days?
The clinical response is anticipatory guidance. Counsel patients on hydration and breaks if they work outside. Talk through tick prevention, what to do during heat waves, when to keep kids inside during poor air quality, and what to do during wildfire smoke events. Pair that with the health co-benefits message that walking, biking, and plant based eating help the patient and the planet at once.
Medical education is moving in the same direction. The Association of American Medical Colleges has been tracking a sharp increase in the share of US medical schools delivering climate content, with the percentage roughly doubling over two to three years. At Harvard Medical School, climate content now lives in every course, integrated across anatomy, physiology, cardiology, pulmonology, and infectious disease. 96 percent of course directors said they wanted it. A study published in PLOS Climate by Basu and colleagues described the implementation and initial evaluation of the integrated curriculum and its novel competency framework, finding statistically significant gains across nearly every competency and substantial increases in student comfort applying climate concepts to patient care.
Takeaway Climate change is not a separate medical specialty. It is a thread that belongs in every part of clinical training and every patient encounter, because patient care is already changing because of it.
What frameworks support meaningful interdisciplinary work between health, urban planning, meteorology, and other fields?
Start with the problem and build the team around it rather than assuming there is one universal configuration. For urban heat, that means city planners, politicians, climate scientists, engineers, and health professionals in the same room. The piece that gets undervalued most often is community voice. Technical experts can produce beautiful designs on a spreadsheet that completely miss what daily life feels like on the ground. The work of meeting with people, hearing concerns, and earning trust is slow and laborious, but solutions that skip it tend not to stick.
How do you reconcile community engaged research ethics with the urgency of the climate crisis?
The urgency is real and it will not go away. The energy transition is not a five or ten year project, and the latest reports show that nearly all new energy demand globally is now being met by clean energy, even though it is not yet displacing fossil fuels fast enough. The Inflation Reduction Act in the US almost stuck but did not have the political teeth to hold, and the worst case scenario is a back and forth that erodes progress. Going fast and going deep are often in tension. Deep community work creates change that holds, and not everyone has to do every part of the job. Partnering with organizations already rooted in a community, and funding them properly, is how researchers and clinicians can stay in their lane without losing the community grounding.
How is medical curriculum evolving to train climate aware clinicians?
Interest is growing fast. The share of US medical schools delivering climate content has roughly doubled over two to three years. The most durable curriculum is integrated, not siloed. At Harvard, every course director agreed to include climate content, and student competencies improved significantly over an 18 month follow up. What students need is a practice rather than a fact set. Memorized numbers age. The habit of asking the right questions, surveilling local threats, and reading the new research as it comes out is what holds up across a career.
How should healthcare think about plastic use and single use supplies without compromising patient care?
Start with the oath. Do no harm. A lot of single use waste is harm to the planet with no clinical benefit, and a growing number of hospitals now have medical directors of sustainability auditing every department. Some choices are real tradeoffs, like anesthetics that vary by orders of magnitude in emissions, and decisions there should involve the anesthesiologists themselves rather than outside pressure. Other choices are pure waste from old habits, and replacing them is often cheaper as well as cleaner. Microplastics are also under researched given how ubiquitous they are, with early evidence pointing to effects on fertility, cancer, inflammation, and autoimmune disease.
How can social determinants of health and climate change move from siloed conversations into urban health infrastructure and policy?
Social determinants of health have gained real traction in clinical and public health settings around poverty, malnutrition, and housing, but environmental exposures still lag in those conversations. The opening is to add climate exposure, air quality, and heat to the same social and structural framing already being used, so that parks, green space, and tree canopy land on the list of upstream interventions. The bigger barrier is commitment to science itself, including sustained funding and an openness to inquiry. Students often understand the integration faster than mid career clinicians, which is why training and continuing education matter so much for the people already in practice.
Is climate change creating new health risks or mainly amplifying structural inequalities?
Mostly amplifying. Low income workers in places like the Indian Sundarbans have endured dangerous heat for generations, and the communities that have suffered first know the most about adapting. There is a real risk that wealthier societies, newly aware of climate impacts, dominate the conversation with their own emotional response and crowd out the communities that have been living with this for decades. The deeper work is to listen to those communities, fund the institutions doing the on the ground engagement, and follow through on global commitments around loss and damage so the countries that caused the disproportionate harm pay for adaptation in the places now bearing the disproportionate cost.
Hope sits in human resilience and creativity. As he put it, "human beings are adaptive, they're creative, we're innovative, like, I believe in human beings. I think our structures and systems have gotten totally messed up." The repair work is structural, but the people are already there to do it.
- Read the Annals of Global Health paper on the climate and health work in the Indian Sundarbans
- Learn about and support the Child in Need Institute, the West Bengal based NGO advancing climate and health work in the Sundarbans and Kolkata
- Use your own sphere of influence as a storyteller, translating climate change into the health of people's families and communities
Mesoamerican Nephropathy (CKDu) — A form of chronic kidney disease seen in young outdoor laborers in hot climates, increasingly tied to chronic heat exposure and dehydration. source
Urban Heat Island — The pattern where dense built environments with little greenery run several degrees hotter than nearby areas with tree canopy and green space. source
Redlining — A 1930s era federal practice that denied investment and mortgages to neighborhoods marked on government maps, with documented downstream effects on heat exposure, air pollution, and health. source
Health Co-Benefits — The health gains that come from climate solutions, like cleaner air from renewable energy, lower disease burden from plant based diets, and active transport from walking and biking. source
Loss and Damage Fund — A UN climate finance mechanism through which higher emitting countries contribute resources to climate vulnerable countries facing unavoidable impacts. source
Anticipatory Guidance — Clinical counseling that prepares patients for foreseeable risks, applied here to heat waves, wildfire smoke, tick exposure, and poor air quality days. source
Harvard Chan C-CHANGE — The Harvard center on climate, health, and the global environment where Dr. Basu serves as faculty.
Child in Need Institute — The India based NGO leading the Sundarbans climate and health program Dr. Basu advises.
IPCC Reports — The Intergovernmental Panel on Climate Change assessment reports, including the 2018 report that shifted Dr. Basu's own career toward climate.
Annals of Global Health Paper — The Sundarbans climate and health paper Dr. Basu offered as a starting point for fellows who want to follow the work more deeply.
Lancet Countdown on Health and Climate Change — The annual tracking of climate and health indicators that includes the redlining, oil and gas wells, and air pollution links referenced in the talk.
PLOS Climate Harvard Medical School Curriculum Study — The Basu led paper on the implementation and initial evaluation of the longitudinal climate, environment, and health curriculum at Harvard Medical School.