This report is the first in a series of papers from the Center for American Progress that examine the nexus of climate change, migration and conflict, and its implications for United States foreign policy and national security. The paper argues that climate change, migration and conflict in the 21st century will test the capabilities of the United States and the world to manage global security in unprecedented ways. This introductory paper lays the foundation for a series of subsequent regional reports focused on northwest Africa, India and Bangladesh, the Andean region and China.