How climate change is feeding big floods around the Mountain West

Recent floods in northern Colorado and Yellowstone National Park highlight some of the ways climate change is making flood risks much worse.

To start, a warmer atmosphere can hold more moisture.

So in our warming world, “this can lead to more intense precipitation rates or heavier rain than we might’ve seen in the past,” said Colorado State University postdoctoral researcher Frances Davenport.

Unfortunately, she said the occasional massive storm system won’t likely stop droughts. Warming weather patterns will cause more evaporation that feeds into those temporary deluges.

Davenport added that in areas that have faced drought and wildfires, a big storm system could cause more flooding and mudslides.

“We just had an incident outside of Fort Collins here … where there was heavy rain on top of the Cameron Peak burn scar, and unfortunately there were two fatalities as a result of that flooding,” she said.

Runoff from burn scars can cause more water pollution, too, especially in areas that rely on fresh mountain streams and rivers.

Davenport said climate change can also cause more rain to fall on snowpack at higher elevations – which was a big contributor to the severe flooding in and around Yellowstone National Park last month.

“The potential for rain-driven floods in the winter, or in sort of the late fall or early spring, is definitely another shift that we’re seeing,” she said.

Davenport said these changing flood risks are something we need to keep in mind. That includes planning construction – and reconstruction – projects carefully to avoid potential new flood pathways.

She said local communities can re-evaluate risks, too, as old flood plans may no longer hold water.

This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Boise State Public Radio in Idaho, KUNR in Nevada, the O'Connor Center for the Rocky Mountain West in Montana, KUNC in Colorado, KUNM in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.

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