Office of Biological and Environmental Research Weekly Report

February 11, 2008

Human-Induced Changes in the Hydrology of the Western United States. Observations have shown the hydrological cycle of the western U.S. changed significantly over the last half of the twentieth century. In an Office of Science sponsored study published in a recent issue of Science Express, Barnett et. al., present results of a regional, multivariable climate-change detection and attribution study, using a high-resolution hydrologic model forced by global climate models. They focus on changes that have already affected this primarily arid region with a large and growing population. The researchers conclude that up to 60% of the climate related trends of river flow, winter air temperature and snow pack between 1950-1999 are human-induced. These results, in conjunction with previous work, suggest a coming crisis in water supply for the western United States.

Reference: T.P. Barnett, D.W. Pierce1, H.G. Hidalgo, C. Bonfils. B.D. Santer, T. Das, G. Bala, A.W. Wood, T. Nozawa, A.A. Mirin, D.R. Cayan1, and M.D. Dettinger, 2008: Human-induced changes in the hydrology of the western United States. Science Express, Jan 31, 2008.

Media Interest: Yes

Contact: Anjuli Bamzai, SC-23.3, (301) 903-0294