As the climate warms, the western U.S. faces more intense wildfires and water shortages. And as one problem gets worse, so could the other.

Kelly Gleason of Portland State University says that after a wildfire, snow that falls in the burned area melts faster and earlier in the spring.

“When a forest burns,” she says, “the canopy tends to get burned away, and so there’s less shading on the snowpack, and more sunlight just makes its way through the canopy to the snow surface.”

What’s more, burned trees slough off charcoal and blackened bits of bark and needles.

“Those particles darken the snowpack surface, and because the snowpack is darker, it absorbs a lot more of that additional sunlight energy.”

Gleason and her team have found that, on average, snow pack disappears five days earlier in forests that have burned. She says the effect persists for at least a decade following the fire occurrence.

“So it’s extensive and it’s persistent across the West,” she says.

Many communities depend on slowly melting snowpack for water during the dry season, so if the snow melts too fast, it can mean dry conditions in months to come.

Reporting credit: Sarah Kennedy/ChavoBart Digital Media.