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Water Resources
Related Links
IPCC Working Group II, Fourth Assessment Report, Chapter 3 (PDF, 38 pp., 3.59 MB, About PDF) 
All regions of the world show an overall net negative impact of climate change on water resources and freshwater ecosystems. Areas in which runoff is projected to decline are likely to face a reduction in the value of the services provided by water resources. The beneficial impacts of increased annual runoff in other areas are likely to be tempered in some areas by negative effects of increased precipitation variability and seasonal runoff shifts on water supply, water quality and flood risks (IPCC, 2007)
The future effects of climate change on water resources in the U.S. and other parts of the world will depend on trends in both climatic and non-climatic factors. Evaluating these impacts is challenging because water availability, quality and streamflow are sensitive to changes in temperature and precipitation. Other important factors include increased demand for water caused by population growth, changes in the economy, development of new technologies, changes in watershed characteristics and water management decisions.
In addition to the typical impacts on water management, climate change introduces an additional element of uncertainty about future water resource management. Water resources in the United States are heavily managed and supplies are scarce in some regions of the country. Strategies have been developed and continue to evolve to address these issues. Implementation of adaptation measures, such as water conservation, use of markets to allocate water, and the application of appropriate management practices will have an important role to play in determining the impacts of climate change on water resources.
The Climate Change Science Program (CCSP) Synthesis and Assessment Product 4.3 (SAP 4.3) will address the effects of climate change on agriculture, land resources, water resources (water quantity and quality), and biodiversity. The primary goal of the report, which will be complete by December 2007, is to enhance understanding and ability to estimate impacts of future climate change on these systems.
The sections that follow will describe:
- Water Availability: How changes in temperature, precipitation patterns, and snowmelt may affect water availability
- Water Quality: How higher water temperatures and changes in the timing, intensity, and duration of precipitation may affect water quality
- Possible Water Resource Impacts in North America
References
- IPCC, 2007: Climate Change 2007: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change [Parry, Martin L., Canziani, Osvaldo F., Palutikof, Jean P., van der Linden, Paul J., and Hanson, Clair E. (eds.)]. Cambridge University Press, Cambridge, United Kingdom, 1000 pp.