Climate Change Is Melting Snowpack, Pushing Some Regions Past a ‘Snow-Loss Cliff’

Snowpack is declining in parts of the Northern Hemisphere—and new research published Wednesday in Nature suggests climate change is responsible. What’s more, scientists say, some regions are approaching a threshold known as the “snow-loss cliff,” beyond which the snowpack decreases rapidly.

Reduced levels of snowpack—calculated as the total mass of snow on the ground—can exacerbate drought and wildfires, threaten drinking and irrigation water, and disrupt businesses that rely on snow, such as ski resorts. And if the planet keeps getting hotter, the loss of snowpack is likely to continue accelerating.

The relationship between climate change and snow is complicated. On shorter timescales, global warming is contributing to increased precipitation and more intense blizzards. But because of warmer temperatures, the snow that falls is melting faster and earlier. It’s also difficult for scientists to untangle whether any observed changes are the result of human-caused climate change or natural climate cycles.

Now, however, researchers say they have shown a clear connection between global warming and changing snowpack.

To reach that conclusion, they studied March snowpack levels for each year between 1981 and 2020 in 169 major river basins in the Northern Hemisphere. They found shrinking snowpack in 70 of those river basins—23 of which they could confidently attribute to human-caused climate change, report Seth Borenstein and Brittany Peterson for the Associated Press. In eight river basins, all located in eastern Siberia, they found the opposite: increasing snowpack levels attributable to climate change.

They also found that the link between temperature and snowpack loss is not linear. When a region’s average winter temperature reaches the “snow-loss cliff”—defined as 17.6 degrees Fahrenheit, or minus 8 degrees Celsius—snowpack loss starts to accelerate exponentially.

“Each degree of warming beyond this cliff is taking more and more,” says study co-author Alexander Gottlieb, a climate scientist at Dartmouth College, to the New York Times’ Delger Erdenesanaa.

Below that temperature, however, any extra moisture in the air from climate change may fall as increased snow and stick around as snowpack—which is what researchers suspect happened in the eight river basins in eastern Siberia.

Areas with average winter temperatures above the 17.6-degree threshold also tend to be the most densely populated, because humans largely inhabit areas with milder climates. More than two billion people live in river basins where average winter temperatures are between 17.6 and 32 degrees Fahrenheit, per the Associated Press.

“Most of the world’s people live in river basins that are at this precipice of falling off an accelerating snow-loss cliff, whereby every additional degree of warming means greater and greater snowpack loss,” says Mankin to CNN’s Rachel Ramirez.

For communities that rely on snowpack for water, the findings spell bad news—and suggest water managers need to make long-term changes to their water supplies now.

“Once a basin has fallen off that cliff, it’s no longer about managing a short-term emergency until the next big snow,” Mankin says in a statement. “Instead, they will be adapting to permanent changes to water availability.”

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Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.