Extreme snow droughts like the one that plagued the West last winter will become more frequent — and eventually the norm — across much of the region as climate change fuels warmer temperatures, according to a new study led by a Colorado School of Mines professor.
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Climate change made the season’s low snowfall four times more likely to occur than during the preindustrial period from 1850 to 1900, says the study, published Monday in the journal Proceedings of the National Academy of Sciences.
The size of the impact surprised the study’s lead author, Adrienne Marshall, who is a computational hydrologist and assistant professor of geology and geological engineering at the School of Mines. She expected an increase in likelihood of just 20% or 30% due to climate change — not the many times over that she found.
“It was a gut punch in a way that (other findings) haven’t been,” she said. “I’m looking at and living through the snow conditions we have right now, and I don’t like it. It makes them real in a way that feels new, even for someone that has been working in this field for a while.”
The lack of snow has translated this summer to extreme drought, parched rivers and reservoirs, water use restrictions and increased wildfire risk across Colorado and the region.
Similarly dry winters will become more common across the West if greenhouse gas emissions are not curbed and climate change continues to intensify. Through the end of the decade, the chance of such a winter will hover around 10%, according to the study.
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By the 2050s, the risk will rise to 32%, and then to 87% by the 2090s.
That means that a snow drought like the one this winter will become the norm — predicted to happen almost every nine years out of 10 — not the exception.
In the Upper Colorado River Basin, which encompasses nearly all of western Colorado, climate change made this winter’s drought 14 times more likely to happen than during the preindustrial era, the study says.
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There’s a slice of less-bad news for those who live in the Upper Colorado River Basin, however.
This winter was so extraordinarily dry that similar winters will remain rare through the end of the century. By the 2090s, the chances of such a snow drought will rise to only 17%, though less-severe snow droughts will still become more common in the decades to come.
The study is one of the first to quantify how the warming climate changes the likelihood of severe snow droughts. But her research adds to studies that have predicted significant impacts on snowfall and snowsports in the coming decades, as The Denver Post explored in its “Endangered Snowpack” project in February.
Marshall was already considering how to apply something called “attribution science” — the process of determining how much of a role climate change plays in a phenomenon — when the winter’s lack of snow became noticeable.
“It provided a great and terrible opportunity to use a case study to further the attribution science we were thinking of,” Marshall said.
The findings are grim, Marshall said, but she hopes they will help people better understand what the future will look like and compel them to reduce emissions and slow the pace of climate change.
“I hope they give us clarity on where we are now and what climate change looks like so far,” she said. “Second, I hope they help us to adapt.”
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