Dr. Daniel Cayan, Scripps Institution of Oceanography, University of California San Diego and U.S. Geological Survey
Water UCI Colloquium Series: Climate Change and California’s Mountain Snowpack | How Much Will We Lose?
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 described 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.
Click here to view PowerPoint: Cayan_Snow_UCI_30Mar2016