Dartmouth Study: Northern Hemisphere "Snow Loss Cliff" Looms

 It hasn't been a great snow year in Vermont, has it?

A strangely snow-free landscape in the northern Champlain
Valley of Vermont on February 13, 2024. Is Vermont going
to be part of a Northern Hemispheric snow loss cliff?

As of Saturday, the snowfall for the season in Burlington was at 34.6 inches. There should have been a little more than 58 inches of snow by this point in the season.  

One local snow drought doesn't mean much for overall snow cover across the entire northern hemisphere. 

But is the Vermont snow drought one tiny symptom of a much larger problem?  Is Vermont - and vast stretches of the Northern Hemisphere - entering what is known as a snow loss cliff?

As the Washington Post tells us:

"Seasonal snow levels in the Northern Hemisphere have dwindled over the past 40 years due to climate change."

 But following the trend is really hard, because of a LOT of variability. 

Washington Post continues:

"'A warmer atmosphere is also an atmosphere that can hold more water,' said Alex Gottlieb, a graduate student at Dartmouth College and lead author on the new study in the journal Nature. That can increase precipitation, spurring snow, or even extreme storms and blizzards that offset the effect of snowmelt and warmer temperatures."

Anchorage, Alaska this winter is Exhibit A

These big storms and blips that temporarily counteract the overall trend makes it harder for scientists to calculate how snowpack has changed over time, says the Washington Post. 

"But the new findings reveal that areas of the United States and Europe are nearing a tipping point where they could face a disastrous loss of snow for decades to come. 

'Once you pass this threshold, which we refer to as the snow loss cliff....even modest amounts of warming you a get really accelerated losses,' Gottlieb said."

The Dartmouth researchers looked at every kind of snow data they could find, focusing on the months of March from 1981 to 2020.   The March data helps capture all the variations in the previous several months' winter weather, such as the occasional big snowstorm or January thaws. 

From there, they used modeling to figure out what snow cover would be like with greenhouse gas emissions or without all that junk going into the atmosphere. 

Here's where the Washington Post cuts to the chase on this snow study:

"The researchers found that the relationship between temperature rise and snow loss is not linear. There is very little snow loss until temperatures pass a certain threshold near the melting point - minus 8 degrees Celsius (17.6 degrees Fahrenheit) - and then, snow levels fall off a 'cliff' and snow loss rapidly accelerates."

This is how it affects humans: More than 2 billion people who rely on snow are at or close to that tipping point where the snow pretty much goes away.  

Once that tipping point hits, the needed snow is pretty much gone forever.

According to that Dartmouth study:

"Once a basin has fallen off that cliff, it's no longer about managing a short-term emergency until the next big snow. Instead, they will be adapting to permanent changes to water availability." 

The Dartmouth study says:

"The sharpest global warming-related reductions in snowpack - between 10% to 20% per decade, are in the Southwestern and Northeastern United States, as well as in Central and Eastern Europe."

We sure as hell see part of that trend in Vermont this winter. For instance, so far this winter, Burlington has seen only three days with six or more inches of snow on the ground.

The Western United States is definitely at risk with this problem. 

We're getting a hint of it this winter in California. There have been plenty of storms in recent months and most of the state has been seeing above normal precipitation.  But at least until recently, snow levels in the Sierra Nevada were a little below average. Part of the reason is the area has seen a lot of warm storms that have partly melted the snow that has fallen there. 

In the Northeast, there's more often than enough rain to keep water supplies intact even as the snow cover diminishes. 

Even so, the situation is cause for worry. As the Dartmouth report tells us:

"The Hudson, Susquehanna, Delaware, Connecticut, and Merrimack watersheds in the Northeastern U.Sl, where water scarcity is not as dire, experienced among the steepest declines in snowpack. But these heavy losses threaten economies in states such as Vermont, New York and New Hampshire that depend on winter recreation, (Dartmouth Associate Professor of Geography Justin ) Mankin says - evening machine-made snow has a temperature threshold many areas are fast approaching."

This winter in the Northeast might not be a one-off. Or if it is a one-off, it still appears to be a preview of what is to come. 

Though this is a widespread problem of course, some far northern areas might have an opposite problem .: Too much snow. A warmer world would allow more moisture laden storms to move north, depositing more snow than before up in parts of the Arctic.