SAN FRANCISCO – Researchers at the University of California, Santa Cruz, say the state could see warmer temperatures and a smaller snowpack over the next half-century because of global warming, a change that could diminish water supplies in a state already familiar with drought.
The researchers found that in 50 years, the San Francisco Bay area could see an average temperature increase of 3 to 4 degrees Fahrenheit over current norms, and the Los Angeles area could see an increase of 5 to 6 degrees Fahrenheit. In the Sierra Nevada, that increase could be significantly higher — as much as 15 degrees Fahrenheit in May.
The study also shows the snowpack could decrease by half in the next 50 years, affecting California’s water supply. The snowpack acts as a reservoir, storing water during the winter and releasing it as it melts.
The report is to be published Friday in the journal Geophysical Research Letters. It looks at the effects of doubling the amount of carbon dioxide in the atmosphere from preindustrial times.
State agencies have established a task force to assess how global warming will affect life in California. That includes how changes in precipitation could affect the state’s forests. Andrea Tuttle, director of the Department of Forestry and Fire Prevention, said one concern is the increased fire danger of drier forests.
The UC Santa Cruz research team, led by Lisa Sloan, associate professor of earth sciences, used computer modeling to look only at California, instead of using more common global modeling systems.
“The hope is studies at this level of detail can produce information for people who want to do something about global warming,” Sloan said.
California’s ecosystems and people depend on the balance of snow and rainfall.
“The snow is a very opportune storage medium in that it releases its water in the spring and summer after the real storminess has died down,” said Dan Cayan, a U.S. Geological Survey researcher and director of the Climate Research Division at the Scripps Institution of Oceanography.
With global warming, “there is going to be earlier and more runoff so we’re going to be in a situation that reservoir capacity isn’t going to be able to store everything,” Cayan said.
Scripps has also done computer modeling to show that much of California’s precipitation would fall as rain instead of snow.