Over 1,100 US counties — more than one-third of all counties in the lower 48 states — now face higher risks of water shortages by mid-century as the result of global warming and more than 400 of these counties will be at extremely high risk for water shortages, based on estimates from a new report by Tetra Tech for the Natural Resources Defense Council (NRDC).
The report uses publicly available water use data across the United States and climate projections from a set of models used in recent Intergovernmental Panel on Climate Change (IPCC) work to evaluate withdrawals related to renewable water supply. The report finds that 14 states face an extreme or high risk to water sustainability, or are likely to see limitations on water availability as demand exceeds supply by 2050. These areas include parts of Arizona, Arkansas, California, Colorado, Florida, Idaho, Kansas, Mississippi, Montana, Nebraska, Nevada, New Mexico, Oklahoma, and Texas. In particular, in the Great Plains and Southwest United States, water sustainability is at extreme risk.
The more than 400 counties identified as being at greatest risk in the report reflects a 14-times increase from previous estimates. For a look at county- and state-specific maps detailing the report findings (including a Google Earth map), go to http://www.nrdc.org/globalWarming/watersustainability/ and http://rd.tetratech.com/climatechange/projects/nrdc_climate.asp.
Sujoy Roy, principal engineer and lead report author, Tetra Tech, said: "The goal of the analysis is to identify regions where potential stresses, and the need to do something about them, may be the greatest. We used publicly available data on current water withdrawals for different sectors of the economy, such as irrigation, cooling for power generation, and municipal supply, and estimated future demands using business-as-usual scenarios of growth. We then compared these future withdrawals to a measure of renewable water supply in 2050, based on a set of 16 global climate model projections of temperature and precipitation, to identify regions that may be stressed by water availability. These future stresses are related to changes in precipitation as well as the likelihood of increased demand in some regions."
A summary of the report and related links are available at http://www.nrdc.org/globalWarming/watersustainability/
•Date: 22nd July 2010 • Region: US •Type: Article •Topic: BC general
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