Dust Created By Human Activity Hastening Snowmelt in Colorado River Basin

Dust created by intensifying human activities in the southwestern United States has caused snow in the Rocky Mountains to melt earlier over the last 150 years and has reduced runoff into the Colorado River basin by about 5 percent, according to a new study. After examining lake sediment cores, researchers found that human-produced dust that settled the region and its winter snowpack increased 500 to 600 percent since the mid- to late-19th century. That dust absorbs more of the sun’s energy, causing snow cover to melt earlier and reducing runoff into the river, according to the NASA study, published in the Proceedings of the National Academy of Science. Using field data and a hydrology model simulating water flow under current conditions and before human settlement, researchers estimated that peak runoff now comes about three weeks earlier than before the West was settled, said Tom Painter, a snow hydrologist at NASA’s Jet Propulsion Laboratory and the research team leader. These results have significant implications for the 27 million people across the U.S. Southwest who rely on the Colorado River water for drinking, irrigation, and industrial use, researchers say.