http://www.cna.org/sites/default/files/MAB_2014.pdf Projected climate change is a complex multi-decade challenge. Without action to build resilience, it will increase security risks over much of the planet. It will not only increase threats to developing nations in resource-challenged parts of the world, but it will also test the security of nations with robust capability, including significant elements of our National Power here at home. Even though we may not have 100 percent certainty as to the cause or even the exact magnitude of the impacts, the risks associated with projected climate change warrant taking action today to plan and prepare for changes in our communities, at home and abroad. When it comes to thinking through long-term global challenges, none are more qualified than our most senior military leaders. Not only do they have decades of experience managing risk and responding to conflict on the battlefield, but they are also experts in geopolitical analysis and longrange strategic planning. Military leaders typically look at challenges with imperfect or conflicting information. Despite not having 100 percent certainty, they weigh the consequences of various courses of action—including the consequences of no action—and make informed decisions based on their experience and risk forbearance. It is through this analytical prism that 11 retired Generals and Admirals came together in 2007, under the moniker of CNA’s Military Advisory Board, to examine the security implications of climate change. Their landmark report, National Security and the Threat of Climate Change, was the first time that such an elite body of military leaders expressed their concern over the security implications of climate change. Now, seven years later, the Military Advisory Board has gathered again to re-examine the nexus of projected climate change and national security. This update reflects their decades of experience as risk managers and geopolitical security experts. With the foundation of CNA’s established analytical prowess, the report deserves strong attention from not only the security community, but also from the entire government and the American public.