Western forests, snowpack, and wildfires appear trapped in vicious climate cycle

When Stephanie Kampf visited one of her wildfire test plots near Colorado’s Joe Wright Reservoir in June of 2021, the charred remains of what had been a cool, shady spruce and fir forest before the Cameron Peak Fire incinerated it nearly took her breath away.

“We would walk through these burned areas and they were just black, nothing growing and already getting kind of hot,” she said. “And then you walk into an unburned patch, and there’d still be snow on the ground. You could almost breathe more.”

The surveys, up at about 10,000 feet in the Rocky Mountains west of Fort Collins, were part of a rapid response science assessment to measure just how much the extreme 2020 wildfire season in the West disrupted the water-snow cycle in the critical late-snowmelt zone that serves as a huge natural reservoir. The snowmelt sustains river flows that nurture ecosystems, fills irrigation ditches for crops, and delivers supplies of industrial and drinking water to communities.

The findings of the study, published earlier this month in the Proceedings of the National Academies of Sciences, suggest that the relationships of snow and water in many Western mountain forests are caught in a vicious climate cycle, with more fires leading to faster snowmelt and reduced water, which, in turn, makes forests more flammable.

The critical areas are at different elevations in various parts of the West, depending on latitude and other geographic factors, but long-term wildfire records suggest that for millennia, fire was a rare visitor in many high-altitude forests, with burn intervals of 200 to 300 years, or even longer in wetter regions.

In Colorado those snow accumulation zones can produce “on the order of half of all streamflows,” with some geographic nuances, said Kampf, a Colorado State University researcher who is currently on sabbatical in Spain, where she is studying the impacts of similarly devastating wildfires that have scorched the Iberian Peninsula in recent years.

During her Colorado research, “It was just so striking to go up to these places and see no snow left,” she said. In one unburned comparison plot a short distance away, there was still more than three feet of snow. “It’s disturbing when you’re accustomed to a place and how it was, and you see it change that much. It’s kind of mind blowing. I suspected that what we experienced in 2020 was outside the norm, but I didn’t realize how far outside the norm it was. And that was just honestly pretty disturbing.”

With the measurements of the Cameron Peak Fire in Colorado as a case study, Kamp’s research team also analyzed satellite data from 1984 to 2020 to show how wildfires are encroaching on the critical snow-storage zones across 70 percent of the Western mountain study area, including the Sierra Nevada, Cascades, Rocky Mountain, and Great Basin ranges.