Last updated October 10, 2018

Perspectives on the causes of exceptionally low 2015 snowpack in the western United States

  • States that over 80 percent of measurement sites west of 115°W experienced record low snowpack in 2015
  • Estimates a return period of 400–1000 years for California's snowpack under the questionable assumption of stationarity
  • Hydrologic modeling supports the conclusion that 2015 was the most severe on record by a wide margin
  • Shows that both human influence and sea surface temperature (SST) anomalies contributed strongly to the risk of snow drought in Oregon and Washington: the contribution of SST anomalies was about twice that of human influence
  • Finds that SSTs and humans appear to have played a smaller role in creating California's snow drought
  • Concludes that in all three states, the anthropogenic effect on temperature exacerbated the snow drought