Back in 2012, the Department of Defense issued a first-of-its-kind "Climate Change Adaptation Roadmap." It was designed to prepare the U.S. military for increasing threats to national security in the form of rising sea levels, increasing global temperatures, and growing conflicts over basic resources like food and water. It stated that "Climate change is expected to play a significant role in the DOD's ability to fulfill its mission in the future."

Fast-forward to today, and Sherri Goodman says the DOD now sees combating climate change as central to its mission.

Sherri was appointed the first-ever deputy undersecretary of defense focusing on environmental security. One of her first assignments was cleaning up nuclear weapons development and production sites. And in 1998, she helped develop the military's first climate change plan, focused mainly on reducing emissions.

This week, host Bill Loveless talks with Sherri about her latest book, "Threat Multiplier: Climate, Military Leadership, and the Fight for Global Security." Sherri explains how far the military's approach to climate change has come over the past 25 years.

Sherri is secretary general of the International Military Council on Climate and Security and a senior fellow at the Wilson Center. She's also founder and former executive director of the Center for Naval Analyses Military Advisory Board and is board chair of the Council on Strategic Risks, which includes the Center for Climate and Security.