This national scientific assessment integrates and interprets the findings of the U.S. Climate Change Science Program (CCSP) and synthesizes findings from previous assessments, including reports and products by the Intergovernmental Panel on Climate Change (IPCC). It analyzes current natural and human-induced trends in global change, and projects future trends impacting the natural environment, agriculture, water resources, social systems, energy production and use, transportation, and human health. It is intended to help inform discussion of the relevant issues by decisionmakers, stakeholders, and the public. As such, this report addresses the requirements for assessment in the Global Change Research Act of 1990.1

The Technical Paper addresses the issue of freshwater. Sea level rise is dealt with only insofar as it can lead to impacts on freshwater in coastal areas and beyond. Climate, freshwater, biophysical and socio-economic systems are interconnected in complex ways. Hence, a change in any one of these can induce a change in any other. Freshwater-related issues are critical in determining key regional and sectoral vulnerabilities. Therefore, the relationship between climate change and freshwater resources is of primary concern to human society and also has implications for all living species.