In the wake of the Bush Administration's admission last week that global warming is a reality and is caused primarily by humans, scientists have released the most detailed study yet of what the warming will mean for California over the next century. Some areas of the state will become dramatically warmer than expected, with severe repercussions for the state's fragile water supply.
Previous forecasts for California relied on global climate models that could cut the state up into only eight or so 300- to 400-kilometer square boxes. So geologists Lisa Sloan, Mark Snyder, and their colleagues at the University of California, Santa Cruz (UCSC), teamed up with researchers at Lawrence Livermore National Laboratory in California to sharpen the picture. Their regional climate model for California, described in an online paper published 7 June in Geophysical Research Letters, divides the state into hundreds of 40-kilometer square boxes, allowing the scientists to predict how global warming will hit different parts of the state.
Sloan found that if atmospheric carbon dioxide levels double over preindustrial levels in the next 50 to 100 years, as the latest projections indicate, the average temperature in the state will increase between 1.4° and 3.8°C. But in some areas, such as the high Sierra Nevada, summer temperatures could increase by as much as 6.1°C and spring snowpack could be cut in half. Although more rain might drench Northern California, Sloan estimates that California could net 15% less water overall. This is bad news for a state already at the edge of its water resources. The biggest problem will be a shift in timing--with more rain in winter, when reservoirs and storage tanks are full and flooding is a problem, and less water arriving as spring snow runoff right before the hot, dry summers.
"What's stunning about this report is the magnitude of some of the changes," says hydroclimatologist Peter Gleick, director of the Pacific Institute for Studies in Development, Environment, and Security, a nonprofit think tank in Oakland, California. "I hope that it's wrong, but if it's right we're in big trouble." The new study is a further confirmation of the urgency of including climate change into policy, he says, especially in California, where the economy and lifestyle are tied very tightly to the water supply.
Related sites
Climate change and
paleoclimate research at UCSC (including Sloan's
research)
Pacific Institute for Studies in
Development, Environment, and Security
Geophysical Research
Letters
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