HR: 0800h
AN: GC21A-0155    [Abstracts]
TI: Detection and Attribution of Anthropogenically Induced Changes in Snowpack Over the Western U.S.
AU: * Pierce, D W
EM: dpierce@ucsd.edu
AF: Scripps Institution of Oceanography, Mail Stop 0224, La Jolla, CA 92093-0224, United States
AU: Barnett, T P
EM: timdotbarnett@ucsd.edu
AF: Scripps Institution of Oceanography, Mail Stop 0224, La Jolla, CA 92093-0224, United States
AU: Hidalgo, H G
EM: hhidalgo@ucsd.edu
AF: Scripps Institution of Oceanography, Mail Stop 0224, La Jolla, CA 92093-0224, United States
AU: Das, T
EM: tdas@ucsd.edu
AF: Scripps Institution of Oceanography, Mail Stop 0224, La Jolla, CA 92093-0224, United States
AU: Bonfils, C
EM: bonfils2@mail.llnl.gov
AF: Lawrence Livermore National Laboratory, PCMDI, L-103, Livermore, CA 94551-0808, United States
AU: Bala, G
EM: bala@llnl.gov
AF: Lawrence Livermore National Laboratory, PCMDI, L-103, Livermore, CA 94551-0808, United States
AU: Mirin, A
EM: mirin@llnl.gov
AF: Lawrence Livermore National Laboratory, PCMDI, L-103, Livermore, CA 94551-0808, United States
AU: Santer, B
EM: santer1@llnl.gov
AF: Lawrence Livermore National Laboratory, PCMDI, L-103, Livermore, CA 94551-0808, United States
AU: Cayan, D
EM: dcayan@ucsd.edu
AF: Scripps Institution of Oceanography, Mail Stop 0224, La Jolla, CA 92093-0224, United States
AU: Cayan, D
EM: dcayan@ucsd.edu
AF: U.S. Geological Survey, Mail Stop 0224, La Jolla, CA 92093-0224, United States
AU: Dettinger, M
EM: mdettinger@ucsd.edu
AF: U.S. Geological Survey, Mail Stop 0224, La Jolla, CA 92093-0224, United States
AU: Wood, A
EM: aww@u.washington.edu
AF: University of Washington, Civil & Environ. Engineering 111 Wilson, Box 352700, Seattle, WA 98195-2700, United States
AB: There has been much previous work on observed changes in the hydrological cycle over the western U.S. in recent decades. These changes have significant societal impacts, since the western U.S. is generally arid and has a large and growing population that puts stress on the available water supply. In some regions, precipitation retained in mountain snowpack acts as a "natural reservoir" of water that is stored during intense winter storms and gradually released during the late spring and summer, when precipitation is generally less. Changes in the retention of winter precipitation in snow could therefore have important consequences on water availability and winter flooding, or alternatively require expensive changes in the water storage infrastructure. In this study we perform a fingerprint-based detection and attribution study to address the question of whether the observed changes in snowpack are due to natural variability, or arise from anthropogenic effects on the climate. We find that the trends in snowpack are unlikely to have arisen from natural variability alone, but are consistent with the changes expected to be seen due to anthropogenic forcing of the climate. An interesting aspect of this is that the Pacific Decadal Oscillation, a natural climate fluctuation, appears to be influenced by anthropogenic effects. While this has been implied in previous works in the literature, the consequences this has for climate over the western U.S. do not seem to have been pointed out, and must be taken into account when trying to understand the relative roles of anthropogenically forced and natural climate variability in the region.
DE: 1630 Impacts of global change (1225)
DE: 1637 Regional climate change
DE: 1655 Water cycles (1836)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting