Apr 23, 2018

Increasing precipitation volatility in twenty-first-century California

Daniel L. Swain, Baird Langenbrunner, J. David Neelin, Alex Hall
Nature Climate Change
  • States that Mediterranean climate regimes are particularly susceptible to rapid shifts between drought and flood—of which, California’s rapid transition from record multi-year dryness between 2012 and 2016 to extreme wetness during the 2016–2017 winter provides a dramatic example
  • Investigates projected future changes in such dry-to-wet events using the Community Earth System Model Large Ensemble of climate model simulations
  • Finds that anthropogenic forcing yields large twenty-first-century increases in the frequency of wet extremes, including a more than threefold increase in sub-seasonal events comparable to California’s ‘Great Flood of 1862’
  • Results also show smaller but statistically robust increases in dry extremes
  • Finds a projected a 25% to 100% increase in extreme dry-to-wet precipitation events, despite only modest changes in mean precipitation
  • Notes that such hydrological cycle intensification would seriously challenge California’s existing water storage, conveyance and flood control infrastructure