The snow line report is based on 70 years of records that show progressively less snow accumulation and rising snow lines in California. The snow line is an elevation, where you get snow above it and rain below.
The study was led by San Diego’s Scripps Institution of Oceanography and it was published last month in the journal Climate Dynamics. One key piece of evidence: The trends we’ve seen in California’s peak winter snowpack.
“We are starting to see that timing of peak snowpack shift earlier, as we are also seeing less total accumulated snowpack. So the way to interpret that is our snow season window is getting a little bit smaller. It's melting earlier and there is less of it to melt,” said study co-author Benjamin Hatchett, a climate scientist with the Desert Research Institute.
The report’s projections for California snowfall is bad news for skiers and for the state’s snowpack. If trends in global warming continue the future will bring even smaller snowpacks and higher snow lines.
Statewide, the estimated rise in the snow line will be 1,600 feet by the end of this century.
“So if you just take that number at face value, that means very different things, depending where you are in the state,” Hatchett said “If you’re in the northern part, where the mountains are quite a bit lower, that rise might mean we rarely see snow in some of the Northern Sierra Nevada and especially the Southern Cascades.”
Snow, Hatchett said, is California’s savings account when it comes to water. The bigger the snowpack and the longer it takes to melt, the more slow, manageable runoff we get and are able to capture for our water supply.
That means if global warming continues unabated, the state will have to find new ways to preserve water.
“California needs to learn how to generate water resources from flood water,” said Alexander Gershunov, a research climatologist at Scripps Oceanography. “Because less and less of those water resources are going to be released gradually in spring and early summer snowmelt.”
As for recreation, some lower elevation ski resorts will no longer be getting snowfall.
“A lot of the ski areas, especially in the Tahoe Basin and along the western side of the Sierra Nevada are very low,” Hatchett said.
Ski resorts between 6,000 and 9,000 feet could lose 70% of their snow accumulations, according to the report. Julian, in San Diego County, is around 4,200 feet.
The report also points out that small changes in winter temperatures can have a big effect on whether some mountain ranges will get snow.
“Among the mountains of the North American West, the Sierra Nevada and Cascade Range are highly sensitive to the snow-to-rain transition. Of the snow falling on these ranges, much falls at temperatures within a few degrees of freezing, making Sierra Nevada snow accumulation particularly vulnerable to warming,” the report said.
Another factor affecting California snowfall is the trend toward atmospheric rivers, warm storm systems that bring California a lot of its precipitation. As those storms increase, California’s highest elevations may get more snow, but they will also cause the state’s snow line to march uphill.
