With frequent and severe disasters repeatedly underscoring the dangers of climate change, scientists across the country have been working to understand the consequences for our hearts, lungs, brains and more — and how to best mitigate them.
The work has relied largely on hundreds of millions of dollars in grants from the National Institutes of Health, a federal agency within the Department of Health and Human Services. But since Robert F. Kennedy Jr. took charge of H.H.S., the Trump administration has indicated that it will stop funding research on the health effects of climate change.
The N.I.H. said in an internal document obtained by The New York Times that it was the agency’s new policy “not to prioritize” research related to climate change. The document also described the organization’s intent not to fund research on gender identity, vaccine hesitancy or diversity, equity and inclusion. N.I.H. employees were instructed to tell researchers to “remove all” mention of the topics and resubmit their applications, even if the main focus was unrelated.
The policy shift on climate change, first reported by ProPublica, stands to drastically limit U.S.-based research into its health effects, which tries to answer questions like whether events like wildfires and heat waves can affect cardiovascular health and pregnancy.
A spokeswoman for H.H.S. said in a statement that the agency was “taking action to terminate research funding that is not aligned with N.I.H. and H.H.S. priorities.” Later, an N.I.H. spokeswoman sent a statement with slightly different wording, saying the agency was “taking action to review, and in some cases freeze or terminate” funding.
Both spokeswomen said the N.I.H. and H.H.S. were prioritizing research that they believed “directly affects the health of Americans” and was in line with the “Make America Healthy Again” agenda. That includes studying the causes of chronic disease, a focus of Mr. Kennedy’s.
But Shohreh Farzan, an associate professor at the University of Southern California’s Keck School of Medicine, said that climate change events were “already directly impacting the health of Americans,” and that one of the best ways to prevent chronic disease was to identify potential causes and symptoms as early as possible.
Dr. Farzan has received N.I.H. funding to study the effects of wildfires and extreme heat on children’s cardiovascular health.
Already, a range of conditions have been linked to extreme weather, including asthma flare-ups, heart attacks, strokes and mental health problems, scientists said. One study found last month that firefighters who fought the Los Angeles blazes in January had elevated lead and mercury in their blood. Scientists have also discovered that some wildfire smoke contains substances associated with chronic conditions like heart disease.
So far, grant recipients have been unable to get answers from direct contacts at N.I.H. about their funding, which they said would be difficult to replace, if not impossible.
“There’s nothing that comes close,” Dr. Farzan said. “This could be a really devastating loss to scientists who have worked for years with a goal of keeping people healthy.”
Without N.I.H. funding, “only a small fraction” of the research at the recently created Cincinnati Center on Climate Change and Health could continue, said Ardythe L. Morrow, the organization’s co-director. The center, part of the University of Cincinnati, has been studying the effects of extreme heat on the immune system and assessing ways to protect high-risk populations.
Grants from foundations are typically smaller than N.I.H. grants, and even wealthy philanthropists’ resources don’t compare to the government’s. Relying on them would leave the country “flying blind” as it figures out how to combat climate change’s health consequences, said Lyndsey Darrow, a professor of epidemiology at the University of Nevada, Reno.
“The health effects of climate change are happening whether or not we fund the science to understand them,” said Dr. Darrow, who is finishing up an N.I.H.-funded project on extreme heat. Her research has found that heat waves increase the likelihood of premature births, especially among groups such as women under 30 and people of color.
Research related to the effects of climate change only used a minimal percentage of N.I.H. funding. In 2024 and 2025, the N.I.H. funded at least 16 studies on the effects of wildfire smoke, and at least seven on extreme heat, out of thousands of total funded studies. But interest in the area had increased.
Several studies are focused on wildfires that spread from forest and brush to highly populated areas, as occurred in Los Angeles. Many questions remain about the health effects of these fires because, until recently, they were rare. What chemicals are in the smoke, and how does that differ by location? What are the short- and long-term effects?
Extreme heat research has similar gaps. Researchers are still trying to understand fully how heat exposure affects the body, especially over prolonged periods.
Perry Hystad, a professor in the College of Health at Oregon State University, had expected to receive a five-year N.I.H. grant to study who is most susceptible to extreme-weather exposure. He planned to follow more than 200,000 people in 27 countries, a far larger subject base than most studies. But he no longer believes he will receive the grant.
Dr. Farzan, the professor at the University of Southern California, feels similarly. If she loses the N.I.H. grant she currently has, she does not expect to be able to replace it.
“Our work isn’t driven by politics or ideology,” she said. “It’s driven by the idea that we can do things now to protect the future health of our children and make our communities places that will be more able to withstand the impacts of extreme events.”
