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.