Human-Induced Changes in the Hydrology of the Western United States

Authors

Tim P. Barnett, University of California
David W. Pierce, University of California
Hugo G. Hidalgo, University of California
Celine Bonfils, Lawrence Livermore National Laboratory
Benjamin D. Santer, Lawrence Livermore National Laboratory
Tapash Das, University of California
Govindasamy Bala, Lawrence Livermore National Laboratory
Andrew W. Wood, University of Washington
Toru Nozawa, National Institute for Environmental Studies
Arthur A. Mirin, Lawrence Livermore National Laboratory
Daniel R. Cayan, University of California
Michael D. Dettinger, University of California

Document Type

Article

Date of this Version

2008

Comments

Published in SCIENCE, 22 FEBRUARY 2008, VOL 319.

Abstract

Observations have shown that the hydrological cycle of the western United States changed significantly over the last half of the 20th century. We present a regional, multivariable climate change detection and attribution study, using a high-resolution hydrologic model forced by global climate models, focusing on the changes that have already affected this primarily arid region with a large and growing population. The results show that up to 60% of the climate-related trends of river flow, winter air temperature, and snow pack between 1950 and 1999 are human-induced. These results are robust to perturbation of study variates and methods. They portend, in conjunction with previous work, a coming crisis in water supply for the western United States.