California “snow deluges” expected to decline significantly by 2100

Extreme snowfall will become less common in California by 2100, a new study found.

Scientists understand how a lack of snow or “snow drought” can affect a region, especially in the midst of a warming climate. However, before now, they did not understand the impact of unusually high levels of snow. And this is becoming more important, as California has just emerged from its second winter of high snowfall.

A new study published in the Proceedings of the National Academy of Sciences used the 2023 winter as a case study to learn more. Computational hydrologist Adrienne Marshall and colleagues from the Colorado School of Mines dubbed the term “snow deluges” to describe the phenomenon recently seen in California.

To reach their findings, they analyzed the unusual snow deluge across the Sierra Nevada mountains in 2023 to assess the impact of “high snow years.”

In 2023, California saw an extremely high amount of snow accumulation, with record snowpack levels. Observations showed the accumulations were a “once-in-54-years event,” with some areas reporting “once-in-320-years accumulations,” the study reported.

By looking at climate projections, scientists found that years like these with the so-called “snow deluges” are set to decline by 58 percent by the end of this century. Years with median levels of snowfall are also estimated to decline by 73 percent, they reported.

“California’s massive snow year of 2023 was record-breaking at 42 percent of snow monitoring sites,” Marshall told Newsweek. “Climate models indicate that in warmer future climates, our biggest snow years will be smaller than our biggest snow years now. Another way of putting this is that a snow deluge like we saw in 2023 would be much more rare in a warmer climate like that we might expect later in the 21st century.”

Similar patterns will also be seen across the wider Western U.S., the study reports.

The findings “underscore the significance of uncovering the impact of climate change on the dynamics of snow deluges and snow droughts in mountainous regions,” the study reports.

“These findings align with a bigger scientific picture that shows declining average snowpack and more frequent snow droughts in California and throughout the West,” Marshall said. “Our new findings suggest that we shouldn’t count on big snow years like the one we had last year to save us in warmer climates.

“This is important because snow acts as a natural reservoir in the mountains that stores water until the late spring and summer when we need it most. Our best opportunities to avoid the worst consequences of this snow loss lie in reducing our greenhouse gas emissions and finding ways to adapt to adapt to changing snow and water availability.”

The study notes that snow deluges can be “both destructive and beneficial” meaning better understanding of the phenomenon can improve management of “snow-dependent ecosystems and economies.”

The 2023 snow deluge in California, in many ways, could be seen as good thing. Before it occurred, the state had been suffering from prolonged drought conditions. As a result, there was a severe lack of snowpack in the surrounding mountains, meaning less water was feeding the state’s reservoirs.

The large snow build-up, however, meant that come spring, it melted into rivers and reservoirs, saving the state from a water crisis. In fact, drought conditions in the state officially ended.

However, the heavy snowfall indicates that climate change is worsening, as weather patterns become more unpredictable and extreme. While the drought has ended for now, climate change could cause another prolonged dry period in the future.

“Snow is important for both ecosystems and water resources, and there’s a lot still to learn about how our biggest snow years—or the loss of them—impact these systems,” Marshall said. “The present study focuses on annual-scale snow deluges, but the largest individual snowfall events could change in different ways.

“We focused on a moderate warming scenario in California and the Western U.S., but it would also be helpful to learn more about how different climate scenarios could affect snow deluges in other parts of the world.”

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