The Pentagon released a report Monday asserting decisively that climate change poses an immediate threat to national security, with increased risks from terrorism, infectious disease, global poverty and food shortages. It also predicted rising demand for military disaster response as extreme weather creates more global humanitarian crises.

The report lays out a road map for how the military will adapt to rising sea levels, more violent storms and widespread droughts. The Defense Department will begin by integrating plans for climate change risks across all of its operations, from war games and strategic defense planning situations to a rethinking of the movement of supplies.

Defense Secretary Chuck Hagel, speaking Monday at a summit meeting of defense ministers in Peru, highlighted the report’s findings and the global security threats of climate change.

“The loss of glaciers will strain water supplies in several areas of our hemisphere,” Mr. Hagel said. “Destruction and devastation from hurricanes can sow the seeds for instability. Droughts and crop failures can leave millions of people without any lifeline, and trigger waves of mass migration.”

“We have already seen these events unfold in other regions of the world,” he added, “and there are worrying signs that climate change will create serious risks to stability in our own hemisphere. Two of the worst droughts in the Americas have occurred in the past 10 years.”

While foreign policy experts have for years warned that climate change could present a future risk to national security, the Pentagon’s characterization of climate change as a threat demanding immediate action represents a significant shift for the military.

In the past, the Pentagon’s response to climate change has focused chiefly on preparing military installations to adapt to its effects, as in protecting coastal naval bases from rising sea levels. But the new report calls on the military to incorporate climate change into broader strategic thinking about high-risk regions — for example, the ways in which drought and food shortages might set off political unrest in the Middle East and Africa.

“One of the differences from previous documents is that they’re really looking at the immediate threat,” said Marcus King, an expert on climate change and international affairs at George Washington University. “The other is that they’re not just looking at installations — they’re looking at a different level, the strategic impact across regions.”

Dr. King and other experts said that the broadened approach would include considering the role that climate change might have played in contributing to the rise of terrorist entities like the Islamic State.

“Climate change and water shortages may have triggered the drought that caused farmers to relocate to Syrian cities and triggered situations where youth were more susceptible to joining extremist groups,” Dr. King said. The Islamic State has seized scarce water resources to enhance its power and influence.

As the Pentagon plans for the impact of climate change, it is conducting a survey to assess the vulnerability of its more than 7,000 bases, installations and other facilities. In places like the Hampton Roads region in Virginia, which houses the largest concentration of American military sites, rapidly rising sea levels have already led to recurrent flooding.

The Pentagon report is the latest in a series of studies highlighting the national security risks of climate change. A May report by a government-funded research group, the CNA Corporation Military Advisory Board, concluded that climate change was becoming a catalyst of global conflict.

In March, the Pentagon’s Quadrennial Defense Review, the agency’s main public document describing the current doctrine of the United States military, drew a direct link between the effects of global warming and terrorism.

The new report does not make any specific budget recommendations for how the military will carry out its climate change agenda. If the Pentagon does request funding from Congress for spending on climate change initiatives, it will clash directly with congressional Republicans, many of whom question the established scientific evidence that human activities are causing climate change. Republicans have fought to block and overturn most of President Obama’s climate change policy initiatives.

“ISIS is still gaining ground and causing havoc in Syria and Iraq, with foreign fighters from over 80 countries coming and going into the fight and then returning to their home country,” Senator James M. Inhofe of Oklahoma, the ranking Republican on the Senate Armed Services Committee and a prominent skeptic on climate change, said of the Pentagon report.

“It is disappointing, but not surprising, that the president and his administration would focus on climate change when there are other, legitimate threats in the world.”

The Pentagon’s increased emphasis on the national security threats of climate change is aimed in part at building support for a United Nations agreement, to be signed next year in Paris, that would require the world’s largest producers of planet-warming carbon pollution to slash their emissions, while increasing aid to help the world’s most vulnerable populations adapt to the effects of global warming.

At a December meeting in Peru, climate change negotiators from around the world will gather to draft that deal. Mr. Hagel’s speech in Peru on Monday appeared intended to build support for that effort.

“In two months, the United Nations will convene countries from around the world here in Peru to discuss climate change,” he said. “Defense leaders must be part of this global discussion. We must be cleareyed about the security threats presented by climate change, and we must be proactive in addressing them.”

Experts say that Mr. Hagel’s increasingly prominent role in pushing for a new global climate change treaty is a sign of how urgent the issue has become.

In 1997, Mr. Hagel, then a Republican senator from Nebraska, played a crucial role in blocking the United States from taking part in the world’s first climate change treaty. He wrote, with Senator Robert C. Byrd, Democrat of West Virginia, a resolution ensuring that the Senate would never ratify the Kyoto Protocol, which required the world’s largest economies to cut their planet-warming fossil fuel emissions.

“It’s significant that the secretary is focusing his remarks at the defense ministers meeting of the Americas on natural disasters and climate change,” said Sherri W. Goodman, senior vice president at the CNA Corporation.

“His making it a priority among the many other things he has to address — ISIS, Ebola, Russia — is a signal that the administration intends to place a priority on this in international climate change negotiations.”

Originally published by The New York Times