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Part of Interstate 70 in Colorado was washed away by flooding and shut down for six months during 2020 and 2021 for repairs. Credit: Colorado Department of Transportation |
In the early morning hours of January 9, 2018, intense rainfall loosened debris and mud in the Santa Ynez mountains, in Santa Barbara County, that had been torched by the Thomas Fire just months before.
The resulting debris flow killed 23 people, injured another 167 and damaged at least 400 homes. UCLA climate scientist Daniel Swain witnessed the aftermath in person.
“It gives you a sense of the physical forces involved,” he said. “You see cars up in trees and boulders the size of trucks strewn about as if they were pebbles in someone’s garden.”
According to a new research paper co-authored by Swain, events like that one could begin occuring more frequently in the western U.S. because of climate change. In the coming years, hilly or mountainous regions within wildfire burn areas will face a higher risk for debris flows, mudslides and flash floods — all of which are likelier to occur on fire-scorched hillsides without vegetation.
That’s because climate change is projected to increase the conditions — higher temperatures, low humidity and precipitation extremes, both wet and dry — that lead to those disasters, according to the study, which was published in Science Advances.