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25 June 2007

PRESS RELEASE: Desert droughts lead to mountain snow loss

Snowy mountain top showing pinking snow from blown-in desert dust
A visible layer of desert dust coats the snows of Mount Sopris in Colorado's Elk Range on May 16, 2007. Dust reduces snow's reflectivity and causes snow to melt approximately one month earlier in the spring, according to a new NSIDC-led study.
High-resolution version
—Image from Penn Newhard

According to a new study led by National Snow and Ice Data Center scientist Tom Painter, wind-blown dust from drought-stricken and disturbed lands can shorten the duration of mountain snow cover hundreds of miles away by one month.

The study, which appeared June 23, 2007, in the online edition of Geophysical Research Letters (GRL), found that seasonal snow coverage in Colorado's San Juan Mountains disappeared a month earlier because of heavy dust deposition from the distant Colorado Plateau, 200 miles (320 kilometers) away, where Colorado, Utah, Arizona, and New Mexico form the Four Corners region. Dust reduces the snow's albedo, or reflectivity, allowing more of the sun's energy to warm the snow pack and causing it to melt earlier.

Tom Painter said, "The connection between dust and lower snow reflectance is already established, but the amount of the impact, measured and modeled, in this integrated system of disturbed desert and mountains stunned us. The fact that dust can reduce snow cover duration so much—a month earlier—transforms our understanding of mountain sensitivity to external forcings."

Prior to the widespread disturbance of the western United States in the late 1800s and its likely enhancement of dust emission to the mountains, the cleaner snow cover would have lasted several weeks longer, the study said.

Snow melt provides drinking water to 1/6 of the world's population and provides an important agricultural and recreational resource for areas like the western United States. The progression of climate change may alter the reliability of spring snow melt's quantity, timing, and duration.

"Recent studies agree that with global warming, the southwest U.S. will be warmer and drier. Enhanced dust deposition is likely, further shortening snow cover duration," Painter said. "Ultimately, a warming climate and the dust it generates will affect river runoff and soil moisture in the mountains, not only in the western United States, but across many of the world's mountains."

Coauthors of the study were Andrew Barrett and Maureen Cassidy, also of NSIDC; Christopher Landry of the Center for Snow and Avalanche Studies; Jason Neff, Corey Lawrence, and G. Lang Farmer of the University of Colorado; Kathleen McBride of Northern Arizona University.

For press inquires or to set up an interview with Painter, Barrett, or Landry, please contact Stephanie Renfrow at srenfrow@nsidc.org or +1 303 492.1497. Reporters who would like a copy of the article should contact Jonathan Lifland at jlifland@agu.org or +1 202 777-7535.

The National Snow and Ice Data Center (NSIDC) is part of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado at Boulder.

Additional information:

State of the Cryosphere: Snow
Learn more about the relationship between Northern Hemisphere snow cover and climate.