A new study by American geologists has indicated that 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.
The study found that seasonal snow coverage in the sub-alpine 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 snow pack and cause it to melt earlier, researchers said.
"The connection between dust and lower snow reflectance is already established, but the amount of impact measured and modelled in this system stunned us," said Tom Painter from the University of Colorado at Boulder's National Snow and Ice Data Centre, who led the study.
"The fact that dust can reduce snow cover duration so much - a month earlier -- transforms our understanding of mountain sensitivity to external forcings," he said.
Findings further revealed that while just three or four significant dust deposition events occurred annually in the San Juan Mountains between 2003 and 2005, eight occurred in 2006.
In 2006, the sub-alpine regions of the San Juans melted out 24 to 35 days earlier, Painter said, quoting ground measurements and computer simulations.
"Recent studies agree that with global warming, the Southwest will be warmer and drier. 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," Painter added.
The findings appear online in the June 23 issue of the Geophysical Research Letters.