This book provides an overview of the U.S. Global Change Research Program (USGCRP) which co-ordinates and integrates scientific research across thirteen agencies of the United States Government and whose mission focuses on changes in the global environment and their implications for society. The environment is changing rapidly. Increases in world population, accompanied by industrialisation and other human activities, are altering the atmosphere, ocean, land, ice cover, ecosystems, and the distribution of species over the planet. Understanding these and other global changes, including climate change, is critical to our Nation's health and economic vitality. Scientific research is critical to gaining this understanding. Research, along with an array of increasingly sophisticated tools for collecting and analysing data, can provide essential knowledge to governments, businesses, and communities as they plan for and respond to the myriad manifestations of global change, including sea-level rise and ocean acidification, heat waves and drought, and the severe storms, floods, and forest fires that pose an ever-growing risk to life, property, and agriculture.