The Trump administration took a major step in its efforts to unravel America’s climate policies on Feb. 12, 2026. It moved to rescind the 2009 endangerment finding, a formal determination that greenhouse gas emissions, such as carbon dioxide and methane from burning fossil fuels, endanger public health and welfare. But the administration’s arguments in dismissing the health risks of climate change are not only factually wrong, they’re deeply dangerous to Americans’ health and safety.
As physicians, epidemiologists and environmental health scientists, we’ve seen growing evidence of the connections between climate change and harm to people’s health.
Here’s a look at the health risks everyone face from climate change.
Extreme heat
Greenhouse gases from vehicles, power plants and other sources accumulate in the atmosphere, trapping heat and holding it close to Earth’s surface like a blanket. Too much of it causes global temperatures to rise, leaving more people exposed to dangerous heat more often.
Most people who get minor heat illnesses will recover, but more extreme exposure, especially without enough hydration and a way to cool off, can be fatal. People who work outside, are elderly or have underlying illnesses such as heart, lung or kidney diseases are often at the greatest risk.
Heat deaths have been rising globally, up 23% from the 1990s to the 2010s, when the average year saw more than half a million heat-related deaths. Here in the U.S., the 2021 Pacific Northwest heat dome killed hundreds of people.
Climate scientists predict that with advancing climate change, many areas of the world, including U.S. cities such as Miami, Houston, Phoenix and Las Vegas, will confront many more days each year hot enough to threaten human survival.
Extreme weather
Warmer air holds more moisture, so climate change brings increasing rainfall and storm intensity and worsening flooding, as many U.S. communities have experienced in recent years. Warmer ocean water also fuels more powerful hurricanes.
Increased flooding carries health risks, including drownings, injuries and water contamination from human pathogens and toxic chemicals. People cleaning out flooded homes also face risks from mold exposure, injuries and mental distress.
Climate change also worsens droughts, disrupting food supplies and causing respiratory illness from dust. Rising temperatures and aridity dry out forests and grasslands, making them a setup for wildfires.
Air pollution
Wildfires, along with other climate effects, are worsening air quality around the country.
Wildfire smoke is a toxic soup of microscopic particles (known as fine particulate matter, or PM2.5) that can penetrate deep in the lungs and hazardous compounds such as lead, formaldehyde and dioxins generated when homes, cars and other materials burn at high temperatures. Smoke plumes can travel thousands of miles downwind and trigger heart attacks and elevate lung cancer risks, among other harms.
Meanwhile, warmer conditions favor the formation of ground-level ozone, a heart and lung irritant. Burning of fossil fuels also generates dangerous air pollutants that cause a long list of health problems, including heart attacks, strokes, asthma flare-ups and lung cancer.
Infectious diseases
Because they are cold-blooded organisms, insects are directly influenced by temperature. So with rising temperatures, mosquito biting rates rise as well. Warming also accelerates the development of disease agents that mosquitoes transmit.
Mosquito-borne dengue fever has turned up in Florida, Texas, Hawaii, Arizona and California. New York state just saw its first locally acquired case of chikungunya virus, also transmitted by mosquitoes.
And it’s not just insect-borne infections. Warmer temperatures increase diarrhea and foodborne illness from Vibrio cholerae and other bacteria and heavy rainfall increases sewage-contaminated stormwater overflows into lakes and streams. At the other water extreme, drought in the desert Southwest increases the risk of coccidioidomycosis, a fungal infection known as valley fever.
Other impacts
Climate change threatens health in numerous other ways. Longer pollen seasons increase allergen exposures. Lower crop yields reduce access to nutritious foods.
Mental health also suffers, with anxiety, depression and post-traumatic stress following disasters, and increased rates of violent crime and suicide tied to high-temperature days.
Young children, older adults, pregnant women and people with preexisting medical conditions are among the highest-risk groups. Lower-income people also face greater risk because of higher rates of chronic disease, higher exposures to climate hazards and fewer resources for protection, medical care and recovery from disasters.
Policy-based evidence-making
The evidence linking climate change with health has grown considerably since 2009. Today, it is incontrovertible.
Studies show that heat, air pollution, disease spread and food insecurity linked to climate change are worsening and costing millions of lives around the world each year. This evidence also aligns with Americans’ lived experiences. Anybody who has fallen ill during a heat wave, struggled while breathing wildfire smoke or been injured cleaning up from a hurricane knows that climate change can threaten human health.
Yet the Trump administration is willfully ignoring this evidence in proclaiming that climate change does not endanger health.
Its move to rescind the 2009 endangerment finding, which underpins many climate regulations, fits with a broader set of policy measures, including cutting support for renewable energy and subsidizing fossil fuel industries that endanger public health. In addition to rescinding the endangerment finding, the Trump administration also moved to roll back emissions limits on vehicles – the leading source of U.S. carbon emissions and a major contributor to air pollutants such as PM2.5 and ozone.
It’s not just about endangerment
The evidence is clear: Climate change endangers human health. But there’s a flip side to the story.
When countries work to reduce the causes of climate change, they help tackle some of the world’s biggest health challenges. Cleaner vehicles and cleaner electricity mean cleaner air – and less heart and lung disease. More walking and cycling on safe sidewalks and bike paths mean more physical activity and lower chronic disease risks. The list goes on. By confronting climate change, we promote good health.
To really make America healthy, in our view, the nation should acknowledge the facts behind the endangerment finding and double down on our transition from fossil fuels to a healthy, clean energy future.
This article includes material from a story originally published Nov. 12, 2025.
Jonathan Levy receives funding from the National Institutes of Health, the Federal Aviation Administration, the City of Boston, the Masschusetts Office of the Attorney General, and the Mosaic Foundation.
Howard Frumkin has no financial conflicts of interest to report. He is a member of advisory boards (or equivalent committees) for the Planetary Health Alliance; the Harvard Center for Climate, Health, and the Global Environment; the Medical Society Consortium on Climate Change and Health; the Global Consortium on Climate and Health Education; the Yale Center on Climate Change and Health; and EcoAmerica’s Climate for Health program, and chairs the National Academy of Medicine Committee on the Roadmap for Transformative Action to Achieve Health for All at Net-Zero Emissions—all voluntary unpaid positions.
Jonathan Patz receives funding from the National Institutes of Health. He is affiliated with the Medical Society Consortium for Climate and Health, and its affiliate Healthy Climate Wisconsin.
Vijay Limaye is affiliated with the Natural Resources Defense Council.
* This article was originally published at The Conversation
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