Announcing the next installment of "Climate Conversations," USGCRP's monthly seminar/webinar series, presented by Dr. Jeffrey S. Deems, and Dr. Thomas H. Painter:

Dust Impacts on Snowmelt Timing & Water Yield in the Upper Colorado River Basin

The waters of the Colorado River serve 27 million people in seven states and two countries but are overallocated by more than 10% of the river's historical mean. Climate models project runoff losses of 7-20% from the basin in this century due to human-induced climate change. Recent work has shown that by the late 1800s, decades prior to allocation of the river's runoff in the 1920s, a fivefold increase in dust loading from anthropogenically disturbed soils in the southwest United States was already decreasing snow albedo and shortening the duration of snow cover by several weeks. We present new results showing that peak runoff at Lees Ferry, Arizona has occurred on average 3 weeks earlier under heavier dust loading and that increases in evapotranspiration from earlier exposure of vegetation and soils decreases annual runoff by more than 1.0 billion cubic meters or ~5% of the annual average. The potential to reduce dust loading through surface stabilization in the deserts and restore more persistent snow cover, slow runoff, and increase water resources in the UCRB may represent an important mitigation opportunity to reduce system management tensions and regional impacts of climate change.

Jeffrey S. Deems, PhD, is a Research Scientist at the National Snow and Ice Data Center and at the NOAA Western Water Assessment at the University of Colorado at Boulder. He conducts research in snow hydrology, lidar remote sensing of snow depth, mountain system hydrologic modeling, and dust and climate change impacts to snow and water resources at catchment to regional scales. At NSIDC he is the Science Liaison for the NASA Operation IceBridge Mission.

Thomas H. Painter, PhD, is a Scientist at the Jet Propulsion Laboratory/California Institute of Technology and a Research Professor at the University of California, Los Angeles. His areas of interest are snow hydrology, radiative impacts of light-absorbing impurities on snow and glacier melt, water resources from mountain snow and ice, multispectral remote sensing and imaging spectroscopy, and solar system astrobiology. Dr. Painter has pioneered our understanding of the impacts of dust emission from land use change on snow and ice cover in mountain systems and the hydrologic response. He is Chairman and organizer of the Working Group on Light-Absorbing Impurities in Snow and Ice. He is the Vice-Chair of the Cryosphere Focus Group of the American Geophysical Union and member of the AGU Eos Editorial Advisory Board.