California's hydropower is vulnerable to climate change, a University of California, Riverside scientist has advised policymakers in "Our Changing Climate," a report released July 31 by the California Natural Resources Agency and the California Energy Commission (CEC). "Climate change is expected to affect the quantity and timing of water flow in the state," explained Kaveh Madani, a former postdoctoral research scholar in UC Riverside's Water Science and Policy Center (WSPC), who led a research project on climate change effects on hydropower production, demand, and pricing in California. "Under dry climate warming, the state will receive less precipitation, with most of it as rain instead of snow, impacting hydropower supply and operations." On average, 15 percent of California's electricity comes from hydropower, a cheap and relatively clean energy source. About 75 percent of this hydropower comes from high-elevation units, located above 1,000 ft. The state has more than 150 high-elevation units, with most of them located in Northern California and the Sierra Mountains. The majority of the high-elevation reservoirs are small in terms of their storage capacity, being built only for hydroelectricity production and no other benefits, such as water supply and flood control. Madani, who led UCR's only research team for CEC's third climate change assessment studies, explained that the major cause of revenue loss is that hydropower prices are expected to decrease in colder months of the year and increase in warmer months. Madani explained that, on average, California could lose up to 20 percent of its hydropower generation under dry climate change, which can result in 8 to 18 percent reduction in hydropower revenues for producers.