Avril Haines, President Biden’s director of national intelligence, told world leaders on Thursday that climate change was no longer a peripheral issue but now “at the center” of U.S. foreign policy, with far-reaching impacts on force deployments and the stability of hard-hit regions.

Ms. Haines, speaking at this week’s virtual global climate conference, struck a tone of urgency at variance with the attitudes of many of her predecessors, who downplayed the role of rising sea levels, droughts, crop failures, fires, diseases and more frequent severe weather events.

“To address climate change properly it must be at the center of a country’s national security and foreign policy,” she said, echoing the words of Lloyd J. Austin III, the defense secretary, who addressed the conference a few minutes earlier.

“It needs to be fully integrated with every aspect of our analysis in order to allow us not only to monitor the threat but also, critically, to ensure that policymakers understand the importance of climate change on seemingly unrelated policies,” Ms. Haines said.

Her comments came after NATO officials announced they would likely agree on a climate “action plan” to reduce emissions by military units and conduct an alliance-wide assessment of the potential threats arising from climate disruptions.

On Thursday, the C.I.A. announced it was adding a new category covering the environment to its World Factbook. The agency’s unclassified guide will now provide the latest country data on climate, air pollutants, infectious diseases, food security, waste and other environmental topics.

Ms. Haines began by saying that the intelligence services had long recognized the importance of climate change — and praised efforts by the C.I.A. over the last three decades to identify the geopolitical impact of climate-based changes in Russia, Asia, Africa and the Arctic.

“We have not always made it a key priority,” she added.

The Biden administration has promised to put a new focus on climate change at the nation’s intelligence agencies. Top intelligence officials all pledged in their confirmation hearings to increase their agencies’ focus on climate.

A pair of recent intelligence reports have presented a grim picture of climate change. The annual worldwide threat assessment, which looks at short-term challenges, said extreme weather caused by climate change would increase the potential for surges in migration and cause instability around the globe.

The changes will “exacerbate political instability and humanitarian crises,” the annual threat report said.

The intelligence agencies issued even more dire warnings with the quadrennial Global Trends report issued on April 8, which argued that climate change would contribute to instability, strain military readiness and encourage new political movements. It said that all societies would be forced to adapt to a warmer planet through changes both small and complex, including the building of massive new sea walls and the relocation of cities and towns.

The report said the physical effects of climate change would intensify over the next 20 years, particularly in the 2030s, and the impact would fall disproportionately on poor parts of the world.

Some Republicans have expressed reservations at expanding the intelligence community’s focus on climate change. At a hearing last week, Ms. Haines argued that while there was partisan division over the issue, intelligence analysts have been examining the issue for decades during administrations of both parties.

“It’s just become increasingly accepted as something that is part of the national security landscape,” she said.