Desert soils have been piling up in the Rocky Mountains since the mid-1800s as human land use activities disturb and break up the soil crust. And during recent years, desert dust has been settling exceptionally thick and dark on the snowpack in the northern Rocky Mountains. Unfortunately, this poses a significant problem for the Colorado River and the 40 million people who depend on this source for water.
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How so? Snow dusted with dark particles absorbs more of the sun’s rays and melts faster than clean snow. And unfortunately, desert dust is causing snowpack to melt many as six weeks earlier than it did in the 1800s.
With increased dust and regional warming expected in the future, the situation seems likely to grow more dire. According to future climate scenarios, the river’s flow could falls by more than 20 percent by 2100. Moreover, warming could make dust problems worse, by increasing the risk of drought.
Studying this dilemma, researchers at NOAA’s Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder suggest that reducing the amount of desert dust swept onto snowy Rocky Mountain peaks could help Western water managers deal with the challenges of a warmer future.
CIRES’ Jeffrey Deems and his colleagues examined the combined effects of regional warming and dust on the Colorado River, which is fed primarily by snowmelt.
Researchers used climate and hydrology models to investigate the effect of that “extreme dust” on the Colorado River’s flow now and in the future, as the Southwest continues to warm. Snowmelt in the extreme dust scenario shifted even earlier in the season, by another three weeks, pulling peak water levels in the Colorado River to earlier in the spring and leaving less water for later in the year.
“Our results suggest that if we can adopt dust-reducing land management strategies and rehabilitate major dust sources, we can keep our snow on the mountains longer, and perhaps offset some of the emerging climate impacts,” said co-author Brad Udall, director of the Getches-Wilkinson Center for Natural Resources, Energy and the Environment at CU-Boulder. “Dust reduction could be a very powerful strategy to help us adapt to the growing impacts of climate change on our precious water supplies in the American Southwest.”
The new assessment was published last week in Hydrology and Earth System Sciences.
See more at the University of Colorado, Boulder.
Rocky Mountain image via Shutterstock.