Oct 8, 2015

Twenty-First-Century Snowfall and Snowpack Changes over the Southern California Mountains

Fengpeng Sun, Alex Hall, Marla Schwartz, Daniel B.Walton, and Neil Berg
American Meteorological Society
  • Projects future snowfall and snowpack changes over the mountains of Southern California using a new hybrid dynamical–statistical framework
  • Analyses variables pertaining to snow for the middle (2041–60) and end (2081–2100) of the twenty-first century under two representative concentration pathway (RCP) scenarios: RCP8.5 (business as usual) and RCP2.6 (mitigation)
  • Compares these four sets of projections with a baseline reconstruction of climate from 1981 to 2000
  • Finds that for both future time slices and scenarios, ensemble-mean total winter snowfall loss is widespread
    • By 2041–60 under RCP8.5, ensemble-mean winter snowfall is about 70% of baseline
    • By 2041–60 under RCP2.6, ensemble-mean winter snowfall is somewhat higher at about 80% of baseline
    • By 2081–2100 under RCP8.5, winter snowfall is about 50% of baseline
    • By 2081–2100 under RCP2.6, only a negligible further reduction from midcentury snowfall totals is seen
  • States these figures are all associated with large intermodel uncertainty because of the spread in the GCM climate projections
  • Assesses snowpack on the ground, as represented by 1 April snow water equivalent
  • States the loss seen in snowpack is generally 50% greater than that seen in winter snowfall because of enhanced snowmelt
  • Finds that by midcentury under RCP8.5, warming-accelerated spring snowmelt leads to snow-free dates that are about 1–3 weeks earlier than in the baseline period