Threat Multiplier takes us onto the battlefield and inside the Pentagon to show how the US military is confronting the biggest security risk in global history: climate change. We learn how the military evolved from an environmental laggard to a climate and clean energy leader. And we discover how a warming world exacerbates every threat--from hurricanes and forest fires, to competition for increasingly scarce food and water, to terrorism and power plays by Russia and China. The Pentagon now considers climate in war games, disaster relief planning, international diplomacy, and even the design of its own bases. No one knows the stakes better than Sherri Goodman, the Pentagon's first Chief Environmental Officer, also known as Deputy Undersecretary of Defense (Environmental Security). In Threat Multiplier, she offers a front row seat to the military's fight for global security, a tale that is as hopeful as it is harrowing.