Desert Dust Melting Alpine Snow

A new study spearheaded by the University of Colorado at Boulder's National Snow and Ice Data Center indicates wind-blown dust from drought-stricken and disturbed lands in the Southwest can shorten the duration of mountain snow cover hundreds of miles away in the Colorado mountains by roughly a month.

Led by Tom Painter, the study found seasonal snow coverage in the subalpine and alpine areas of the San Juan Mountains of southwestern Colorado disappeared by about 30 days earlier in 2006 because of heavy dust deposition from the Colorado Plateau roughly 200 miles away. The dust, which probably came from northeast Arizona and northwest New Mexico deserts, reduced the snow's reflectivity, allowing more of the sun's energy to warm the snowpack and cause it to melt earlier.

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

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