A new analysis suggests that by 2050 climate change will raise the risk of water shortages in one-third of U.S. counties. The report  was commissioned by the Natural Resources Defense Council (NRDC), which is calling for Congress to pass climate legislation to reduce the risk of shortages. Although it doesn't break new scientific ground, the report does provide a good overview of the problem.
Analysts led by environmental engineer Sujoy Roy of Tetra Tech Inc. in Lafayette, California, pulled together the most current projections from 16 climate models. They also gathered county-level data on water resources and consumption by cities, farms, and other users. In 14 states, particularly in the Great Plains and southwest, 400 counties will face an "extremely high risk" of water shortages by midcentury. All told, 1100 counties face at least a high risk.
Although not the first analysis of possible water shortages in the United States, the report does drill down deeper, Roy says. "The particular novelty is the spatial resolution and the ability to zoom in at a more detailed level than before." NRDC created a Google Earth tool  for viewing the results.
That high-resolution view could help build awareness of the risks from climate change, says the U.S. Department of Agriculture's Jerry Hatfield, an author on a 2008 climate change impacts report . "You have to get [the analysis] at a level at which people will take the message to heart."