Understanding End-of-Century Snowpack Changes Over California's Sierra Nevada

Abstract

This study uses dynamical and statistical methods to understand end-of-century mean changes to Sierra Nevada snowpack. Dynamical results reveal that middle-elevation watersheds experience considerably more rain than snow during winter, leading to substantial snowpack declines by spring. Despite some high-elevation watersheds receiving slightly more snow in January and February, the warming signal still dominates across the wet season and leads to notable declines by springtime. A statistical model is created to mimic dynamical results for 1 April snowpack, allowing for an efficient downscaling of all available general circulation models from the Coupled Model Intercomparison Project phase 5. For all general circulation models and emission scenarios, dramatic 1 April snowpack loss occurs at elevations below 2,500 m, despite increased precipitation in many general circulation models. Only 36% (±12%) of historical 1 April total snow water equivalent volume remains at the century's end under a “business-as-usual” emission scenario, with 70% (±12%) remaining under a realistic “mitigation” scenario.