Water: The Potential Consequences of Climate Variability and Change for the Water Resources of the United States

September 26, 2000, Oakland, CA – Today, the Pacific Institute and the Department of the Interior released a new report titled “Water: The Potential Consequences of Climate Variability and Change for the Water Resources of the United States” prepared as part of the U.S. Global Change Research Program’s National Assessment of the Potential Consequences of Climate Change.

The report, a two-year compilation of scientific studies by representatives of the government, corporate and non-governmental organization sectors to evaluate the implications of both existing climate variability and future climate change on national water resources was prepared under the leadership of the Pacific Institute. It concludes that climate changes in this century may have serious implications for U.S. water resources.

“This reports is another reminder that climate change is upon us, and a wake up call that we need to begin long range planning efforts to prepare for the eventuality of global warming,” said Deputy Secretary of the Interior David J. Hayes. “The good news is that the analysis and findings in this report are the basis for beginning that planning process now,” Hayes added.

The buildup of heat-trapping greenhouse gases in the atmosphere over the past century, primarily from fossil fuel combustion, has substantially contributed to a temperature increase of about two-thirds of a degree Celsius in the United States, with 1998 the warmest year on record. The report concludes that this has already resulted in substantial thawing of the permafrost in the Alaska Arctic and unprecedented melting of mountain glaciers, an increase in sea level of between 10-20 centimeters, and an alteration of water runoff patterns as a consequence of decreased snow and ice cover and earlier melting.

Climate models project that temperatures could increase another 3-6 degrees Celsius bythe end of this century. Warming of this magnitude could seriously affect U.S. water resources. Among the impacts outlined by the study are:

  • Snowfall and snowmelt will be significantly affected in the Sierra Nevada, Rocky Mountains, and the Pacific Northwest, leading to changes in the timing and magnitude of runoff;
  • Rising sea levels will threaten coastal aquifers and water supplies. Vulnerable regions include Cape Cod, Long Island, the coastal aquifers of the Carolinas, and the central coast of California;
  • The risk of increased flooding may be as serious and widely distributed as the adverse impacts of droughts;
  • Changes associated with climate change, such as increases in lake and stream temperatures, permafrost melting, and a reduction of water clarity, could seriously threaten fish and water species and critical habitats, such as wetlands.

Peter Gleick, President of the Pacific Institute, and the lead author of the study, emphasizes the need to focus on measures to reduce the risks of climate change and to develop effective ways to adapt to changes that are inevitable. “Sole reliance on traditional management responses is a mistake,” Gleick stated, “water managers need to integrate possible climate change impacts into their planning processes and to build flexibility into the system to maximize our ability to respond to changing conditions.” Gleick also emphasized the importance of water conservation and efficiency programs, and the need to look beyond traditional options for water supply options, such as dams and reservoirs to potential alternative sources of supply, including wastewater reclamation and reuse and desalination.

“Water: The Potential Consequences of Climate Variability and Change for the Water Resources of the United States” is available online.