This report describes the activities and plans of the Climate Change Science Program (CCSP), which incorporates the U.S. Global Change Research Program, established under the Global Change Research Act of 1990, and the Climate Change Research Initiative, established by the President in 2001. CCSP coordinates and integrates scientific research on climate and global change supported by 13 participating departments and agencies of the U.S. Government. The document describes a wide range of advances in understanding the underlying processes responsible for climate variability and change, such as advances in understanding of climate change at high latitudes. It also describes progress on understanding the ongoing and projected effects of climate change on nature and society, including the interconnected relationships between climate, forests, and wildfire. The document also describes how observational and predictive capabilities are being improved and used to create tools to support decision making at local, regional, and national scales to cope with environmental variability and change.