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University study shows wildfires have effect on snowmelt in Western states

by KOIN-TV, Portland, Ore. |

Here's the cycle: A forest fire causes snow to melt earlier in the season, which may affect water supplies and cause more fires.

That's the finding of a new Portland State University study and published in Nature Communications.

The study, done in conjunction with the Desert Research Institute and the University of Nevada, shows that fire-snowmelt cycle will increase as forest fires become more frequent, last longer and cause more destruction in a warmer, drier climate.

More than 11 percent of all forests in the Western U.S. are seeing snowmelt earlier because of the fires, the study found.

Using state-of-the-art lab measurements, researchers found the snow melted about five days earlier after a fire – and is sped up the timing of the snowmelt for as long as 15 years after the fire.

Kelly Gleason, the lead author of the study and an assistant professor at PSU’s College of Liberal Arts and Sciences, said there are two reasons for the earlier snowmelt.

Fire often consumes the trees that provide shade. Less shade means more sunlight, which leads to more and faster snowmelt.

The other reason is more important, researchers said. The charred wood, bark and debris left behind, known as black carbon, makes the snow darker and lowers its reflectivity. The result, researchers noted, "is like the difference between wearing a black t-shirt on a sunny day instead of a white one."