The Real Culprit Behind Snowmelt Floods Isn’t Temperature—It’s Dirt

Every spring in the western United States, snow melts off mountains, feeding rivers with surges of water that can cause disastrous floods. But warm weather isn’t the main culprit, a new study finds. Instead, dusty soil that sticks to snow can darken it and accelerate its melting. The findings could establish a new way of forecasting snowmelt flooding—and suggest that the current prediction system has been getting it all wrong. The work is “groundbreaking,” says Adrian Harpold, a hydrologist at the University of Nevada in Reno who wasn’t involved with the study. “Dust is a really big deal for snowpack.”