Scientists from the Scripps Institution of Oceanography have analyzed the current and predicted “water budget”the amount of water going in and coming outof Lakes Mead and Powell, critical reservoirs along the Colorado River. Much of the urban population in the southwest as well as California’s most productive agricultural areas depend on water from the Colorado River. Increased temperatures from global warming are decreasing rain and snowfall and are increasing evaporation in the Colorado River watershed. This is reducing runoff into the reservoirs. The team predicts the water storage in Lakes Mead and Powell has a 50 percent chance of becoming exhausted by 2021 if climate change reduces runoff as predicted and if water consumption continues at current levels. This scenario would have dire consequences for the American Southwest.