Inevitable End-Of-Century Loss of Spring Snowpack over California's Sierra Nevada

Snowpack in California's Sierra Nevada is a critical ecological and water resource. It is vulnerable to climate change, but is largely unrepresented in current global climate models. Here we use a downscaling technique incorporating both dynamical and statistical methods to project end-of-century changes in this region's snow water equivalent at the end of the wet season. The technique produces outcomes for all available CMIP5 GCMs and the four greenhouse gas forcing scenarios adopted by the IPCC. For all GCMs and forcing scenarios, significant snow loss occurs at elevations below 2500 meters, despite increasing precipitation in many GCMs. The approximate intermodel range in percent of total snow remaining in the entire region is 60-85% for a likely “mitigation” scenario, and 35-55% for the “business-as-usual” scenario. Thus we conclude that significant snowpack decrease by century's end is inevitable in the California's Sierra Nevada, even if the disappearance of more than half the snowpack can be averted through greenhouse gas emissions reductions.