Historically, mountain snowpack has provided a crucially important fraction of California’s water supply, but with projected climate warming in future decades, it is likely that the snow pack will diminish. Snow pack has varied considerably between years, mostly in response to fluctuations in the seasonal accumulation of precipitation, while it has only incrementally affected by seasonal variations in temperature. In the future, however, the affect of temperature will likely play a larger role. An ensemble of downscaled global climate model (GCM) simulations under two emissions scenarios exhibits+1°C to more than +3°C warming by 2100 over the California snow region, which, on average, greatly exceeds historical temperature deviations. Precipitation over the region retains a healthy level of interannual variation, but shows little trend. Using VIC hydrological model simulations from the climate model projections, precipitation fluctuations continue to contribute strongly to the year-to-year variation in snow pack, but the temperature influence in diminishing spring snowpack increases markedly in future decades.
The talk will describe the diminishing odds of achieving spring snow water volume that meets or exceeds median historical levels, and the increasing likelihood of extremely low snow water amounts.
About the Speaker:
Dr. Daniel R. Cayan has spent his career in climate research. He is stationed at Scripps Institution of Oceanography but holds a half time appointment with the US Geological Survey. He studied at UC San Diego, Scripps Institution of Oceanography in obtaining his PhD.
His work is aimed at understanding climate variability and changes over the Pacific Ocean and North America and how they affect the water cycle and related sectors over western North America. Cayan has specific interests in regional climate in California and has played a leading role in programs to deliver improved climate information to decision makers: the California Nevada Applications Program (CNAP), sponsored by the NOAA RISA Program and the Southwest Climate Science Center, sponsored by the US Geological Survey, Department of Interior. He has worked with the State of California in a series of climate vulnerability and adaptation assessments.