Perhaps no agency has embraced climate change adaptation with as much enthusiasm as the Defense Department. Changing weather patterns, rising sea levels and a melting Arctic will affect every aspect of the military’s mission, from base construction to troop deployment, the department says.

As part of its 2010 Quadrennial Defense Review, the Defense Department recognized that climate change will affect the military in two broad ways: Infrastructure, including bases, may no longer be viable because of climate threats such as a rising sea level and melting permafrost; and climate change events, such as floods and droughts, could accelerate conflicts and instability in the world.

Retired Vice Adm. Dennis V. McGinn, president and chief executive of the American Council on Renewable Energy, said in a recent radio interview that Pakistan is an example of a country that could turn on a dime because of climate events and become a threat to national and global security if major floods or other weather events become more frequent. Such natural disasters, which displace people and disrupt basic services, put tremendous pressure on society and government, making a country more susceptible to major governmental takeovers or other changes.

“Oh, and by the way, they have nuclear weapons,” he said.

McGinn was among more than three dozen defense and national security officials who, under the Partnership for a Secure America, recently released a letter urging Congress and the president to take more action to improve the nation’s security by addressing global climate change.

“It is in our national interest to confront the risk that climate change in vulnerable regions presents to American security,” the letter said. “We must offer adaptive solutions to communities currently facing climate-driven displacement, support disaster risk reduction measures and help mitigate potential future impacts through sustainable food, water and energy systems.”