The U.S. Geological Survey (USGS), a nonregulatory Federal science agency with national scope and responsibilities, is uniquely positioned to serve the Nation's needs in understanding and responding to global change, which includes changes in climate; sea level; land use and land cover; ecosystems; and the global water, carbon, and nitrogen cycles. Global change is among the most challenging and formidable issues confronting our Nation and society. Scientists agree that global environmental changes during this century will have far-reaching societal implications Intergovernmental Panel on Climate Change (IPCC), 2007; USGCRP, 2009]. In the face of these complex challenges, the Nation can benefit greatly by using natural science information in decisionmaking.