Snowpack shrinks worldwide due to climate change and it will get worse

River basins around the world that used to be regularly covered in snow are experiencing shrinkage, and climate change is to blame, according to a new study.

“Many of the world's most populated basins are on the brink of rapid reduction in snowfall,” was the conclusion of the study on snow accumulation since 1981, which was published Wednesday in the journal Nature.

That's because the research discovered a key threshold for the Northern Hemisphere's snowpack future: minus 8 degrees Celsius (17.6 degrees Fahrenheit). When the average winter temperature falls below this threshold, the snowpack typically survives due to the low temperature. However, in regions where the average winter temperature exceeds minus 8°C, the winter dreamscapes are prone to melting. And this process is accelerating.

“You're potentially in this regime of really rapid, accelerated losses with warming,” said Alexander Gottlieb, an Earth systems scientist at Dartmouth College and lead author of the study.

Climate change’s impact on snowpacks uncertain

Similarly, ground observations, satellites, and climate models do not consistently agree on whether global warming is chipping away at the snowpacks that accumulate in high-elevation mountains, making the management of water scarcity that would result for many populations centers more complicated.

Now, a new Dartmouth study removes the uncertainty from these observations and provides evidence that human-driven climate change has significantly shrunk seasonal snowpacks across most of the Northern Hemisphere over the past 40 years.

The Southwestern and Northeastern United States, as well as Central and Eastern Europe, show the most marked reductions in snowpack due to global warming - at a rate between 10% to 20% per decade.

The researchers report in the journal Nature that the extent and speed of this loss potentially put the hundreds of millions of people in North America, Europe, and Asia who depend on snow for their water on the precipice of a crisis that continued warming will amplify.

"We were most concerned with how warming is affecting the amount of water stored in snow. The loss of that reservoir is the most immediate and potent risk that climate change poses to society in terms of diminishing snowfall and accumulation," said first author Alexander Gottlieb, a Ph.D. student in the Ecology, Evolution, Environment and Society graduate program at Dartmouth.

Vulnerable watersheds to warming

"Our work identifies the watersheds that have experienced historical snow loss and those that will be most vulnerable to rapid snowpack declines with further warming," Gottlieb said.

"The train has left the station for regions such as the Southwestern and Northeastern United States. By the end of the 21st century, we expect these places to be close to snow-free by the end of March. We're on that path and not particularly well adapted when it comes to water scarcity."

Mankin and Gottlieb used variations of conventional scientific techniques to show that climate change clearly contributed to the melt in 23 of those declining snowpacks. They found in eight river basins, all located in frozen eastern Siberia, that global warming contributed to snow accumulation as precipitation increased, but temperatures remained cold enough to preserve it.

The Hudson, Susquehanna, Delaware, Connecticut, and Merrimack watersheds in the Northeastern U.S., where water scarcity is not as dire, have experienced some of the steepest declines in snowpack. Mankin said that these heavy losses pose a threat to economies in states like Vermont, New York, and New Hampshire, which rely on winter recreation - even machine-made snow has a temperature threshold that many areas are rapidly approaching.

Snow’s impact on global warming varies

"The recreational implications are emblematic of how global warming disproportionately affects the most vulnerable communities," Mankin said. "Ski resorts at lower elevations and latitudes have already been contending with year-on-year snow loss. This will just accelerate, making the business model inviable."

"We'll likely see further consolidation of skiing into large, well-resourced resorts at the expense of small and medium-sized ski areas that have such crucial local economic and cultural values. It will be a loss that will ripple through communities," he said.

Mankin explained that snow comes with uncertainties that have often hidden the effects of global warming. “Contrary to popular belief, snow is not easy to measure, and it doesn’t just decrease with warming. Moreover, the loss of snow doesn’t have the same impacts everywhere,” Mankin clarified.

He further stated, “Snow observations become particularly complex at the regional scales, which are most relevant for assessing water security. Snow is extremely sensitive to variations in temperature and precipitation within the winter season. Consequently, the risks from snow loss vary greatly across regions. For instance, the implications are not the same in New England as in the Southwest, or for a village in the Alps as in high-mountain Asia.”

Climate change’s impact on snowpack

In their research, Gottlieb and Mankin studied how global warming affects temperature and rainfall, and how these changes impact the snowpack in 169 river basins in the Northern Hemisphere from 1981 to 2020. They found that losing snowpack could lead to less water in rivers, streams, and soil in the spring when it’s most needed by ecosystems and people.

They used a machine-learning model to analyze thousands of data points and climate model experiments. This data included information on snowpack, temperature, rainfall, and runoff in the Northern Hemisphere’s watersheds.

This analysis helped them figure out where snowpack was being lost due to warming. It also lets them study how changes in temperature and rainfall, which are driven by climate, can both decrease and increase the thickness of the snowpack.

The researchers also looked at the uncertainties in the models and observations to improve what scientists had previously missed when studying the impact of climate change on snow. In a 2021 study, Gottlieb and Mankin used these uncertainties to better predict water availability by improving how scientists measure snow depth and define snow drought.

Schindler emphasized the need for strong, large-scale action. Aspen Snowmass, along with other ski areas, is becoming more involved in climate activism. They see the importance of advocating for policies that are good for the climate, especially if they want to continue operating in a world that’s getting warmer.

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