Climate contradiction: Less snow, more blizzards
Her study used new computer models to simulate the climate in 60 years to 100 years as carbon dioxide levels soar. She found large reductions in snowfall throughout much of the world, especially parts of Canada and the Andes Mountains. In the United States, her models predict about a 50 percent or more drop in annual snowfall amounts along a giant swath of the nation from Maine to Texas and the Pacific Northwest and California’s Sierra Nevada mountains.
This is especially important out West, where large snowcaps are natural reservoirs for a region’s water supply, Kapnick said. And already in the Cascades of the Pacific Northwest and in much of California, the amount of snow still around on April 1 has been declining so that it’s down about 20 percent compared with 80 years ago, said Philip Mote, who heads a climate change institute at Oregon State University.
Kapnick says it is snowing about as much as ever in the heart of winter, such as February. But the snow season is getting much shorter, especially in spring and in the northernmost areas, said Rutgers’ David Robinson, a co-author of the study on extreme weather that will be published in the Bulletin of the American Meteorological Society.
The Rutgers snow lab says this January saw the sixth-widest snow cover in the Northern Hemisphere; the United States had an above average snow cover for the last few months. But that’s a misleading statistic, Robinson said, because even though more ground is covered by snow, it’s covered by less snow.
And when those big storms finally hit, there is more than just added moisture in the air; there’s extra moisture coming from the warm ocean, Robinson and Oppenheimer said. And the air is full of energy and is unstable, allowing storms to lift yet more moisture up to colder levels. That generates more intense rates of snowfall, Robinson said.
“If you can tap that moisture and you have that fortuitous collision of moist air and below-freezing temperatures, you can pop some big storms,” Robinson said.
Pennsylvania State University climate scientist Michael Mann points to the recent Northeast storm that dumped more than 30 inches in some places. He said it was the result of a perfect set of conditions for such an event: arctic air colliding with unusually warm oceans that produced extra large amounts of moisture and big temperature contrasts, which drive storms. Those all meant more energy, more moisture and thus more snow, he said.