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Attribution of Declining Western U.S. Snowpack to Human Effects

TitleAttribution of Declining Western U.S. Snowpack to Human Effects
Publication TypeJournal Article
Year of Publication2008
AuthorsPierce, D. W., T. P. Barnett, H. G. Hidalgo, T. Das, C. Bonfils, B. D. Santer, G. Bala, M. D. Dettinger, D. R. Cayan, A. Mirin, A. W. Wood, and T. Nozawa
JournalJournal of Climate
Date PublishedDEC 1 2008
ISBN Number0894-8755
Keywordsclimate-change, GREENHOUSE-GAS, MOUNTAIN SNOWPACK, NORTH-AMERICA, PRECIPITATION, temperature, trends, united-states, variability, WORLDS OCEANS

Observations show snowpack has declined across much of the western United States over the period 1950-99. This reduction has important social and economic implications, as water retained in the snowpack from winter storms forms an important part of the hydrological cycle and water supply in the region. A formal model-based detection and attribution (D-A) study of these reductions is performed. The detection variable is the ratio of 1 April snow water equivalent (SWE) to water-year-to-date precipitation (P), chosen to reduce the effect of P variability on the results. Estimates of natural internal climate variability are obtained from 1600 years of two control simulations performed with fully coupled ocean-atmosphere climate models. Estimates of the SWE/P response to anthropogenic greenhouse gases, ozone, and some aerosols are taken from multiple-member ensembles of perturbation experiments run with two models. The D-A shows the observations and anthropogenically forced models have greater SWE/P reductions than can be explained by natural internal climate variability alone. Model-estimated effects of changes in solar and volcanic forcing likewise do not explain the SWE/P reductions. The mean model estimate is that about half of the SWE/P reductions observed in the west from 1950 to 1999 are the result of climate changes forced by anthropogenic greenhouse gases, ozone, and aerosols.

DOIDOI 10.1175/2008JCLI2405.1
Reference number


Short TitleAttribution of Declining Western U.S. Snowpack to Human Effects
Citation Key160