This year’s devastating snow drought in the Upper Colorado River Basin was made 14 times more likely by years of global climate change, according to a new study by Colorado School of Mines researchers, who are increasingly linking short-term weather disasters to decades of warming.
Low snow years have always been possible in the West, the researchers said, but climate change is making it more frequent and more devastating.
By the 2050s, their modeling shows, snowpack drought like the states west of the Continental Divide experienced this past winter will be happening more than three of every 10 years, and nearly nine of every 10 years by the 2090s.
Warmer temperatures in the West have also intensified the impacts of the worst drought winters such as 2025-26, according to the research published in the “Proceedings of the National Academy of Sciences.” The current snowpack drought, coming amid climate change, robbed 25% more moisture from snowpack than a similar-scale drought occurring before the Industrial Age advent of heavy fossil fuel use and global warming.
That’s an entire Lake Mead’s worth of water, the largest reservoir in the United States.
The study modeling assumes current “moderate” levels of greenhouse gas emissions will continue for decades, a scenario most international climate scientists have agreed upon. That leaves room for change and optimism, said co-author Adrienne Marshall, a climate hydrology expert and assistant professor of geology and geological engineering at Mines.
“I hope this study is useful in that we can look at this snow year and say, ‘I don’t like this,’ and that it helps motivate us to think about how we can adapt to and avoid these very low snow years,” Marshall said.
“Lower emissions scenarios would reduce this risk and should be pursued ambitiously,” the study authors say.
And for the nearer term, by the 2050s, the warning from the study is to adapt, Marshall said. Even if long-term emissions are lowered, near-term changes are already baked into rising temperatures and likelihood of drought.
Coming in a week where Denver Water has warned 1.5 million customers they aren’t doing nearly enough to save 20% of water use from average years, practical implications might be obvious, the researchers said.
“Anecdotally, I feel like I see more of my neighbors pursuing lawn replacement projects than I ever have before, and switching to low-water landscaping,” Marshall said. “And I think it’s worth asking ourselves, how can we do that on a societal level?”
For years, climate scientists made a clear distinction between short-term severe weather events and the long-term patterns brought by climate change. One good winter snowfall, for example, does not mean climate change is over.
But increasingly, climate scientists are making direct connections, including about the European heat waves and other events. “The field of extreme event attribution has really grown over the last 20 years or so,” Marshall said.
“Along with everybody else, I was watching this year’s snow conditions kind of evolve over the course of the winter, and was asking myself the glaring question: To what extent was this caused by climate change?” Marshall said. “This study was among the first to take those methods and apply them to snow drought conditions.”
The researchers used modeling to take this season’s historically low snow conditions and compare it to snow drought frequency and severity from before climate change, about 1850 to 1900. “What was the probability of having an event that bad in the world we’re living in now, versus the world without climate change?” Marshall explained.
The results showed that in the West as a whole, climate change made this year’s severe drought more than four times more likely than before global warming began. In the Upper Colorado River basin, with Colorado as the headwaters, that risk exploded to 14 times more likely after climate change, Marshall said.
Without major policy changes that would reduce carbon emissions, things appear more and more dire the further the researchers, she said.
“In the 2020s, we’d expect about one out of every 10 years to be this bad” under emissions assumptions, Marshall said. “By the 2050s around 32% of the years — three out of every 10 years to be this bad in the Western U.S. And then by the 2090s, 87% of the years. So by late in the century, most of the time, we would expect to have as much or less snow as we did this year.”