SOURCE: Yale Environment 360
DATE: November 30, 2017
SNIP: High in the snowfields atop the Rocky Mountains in Colorado, things are not as pristine as they used to be. Dust from the desert Southwest is sailing into the Rockies in increasing quantities and settling onto the snow that covers the peaks, often streaking the white surface with shades of red and brown.
The amount of dust that settles on snow varies from year to year. From 2005 to 2008, about five times as much dust fell on the Rockies as during the 1800s, and those years are characterized by researchers as moderately dusty, according to a recent study. In 2009 and 2010, however, the Rockies saw an extreme dust scenario, with the amount of dust blowing onto the mountains mushrooming to five times more than those moderate years. The cause, scientists say, was increasing drought — linked to a warming climate — and human development.
Because darker, dust-flecked snow absorbs more solar energy and warms faster than pure white snow, it means snow cover melts earlier — a lot earlier. “It’s not subtle at all,” said Jeff Deems, a research scientist with the National Snow and Ice Data Center in Boulder, Colorado. “There is 30 to 60 days difference in the melt out. Over a larger watershed, it’s massive.”