Scientist: Recent storms consistent with warming planet
April 2, 2011
SOUTH LAKE TAHOE – Global warming could make record-setting snowstorms in some parts of the country more common, but not in the Sierra Nevada, according to scientists with the Union for Concerned Scientists.
“Heavy snowstorms are not inconsistent with a warming planet,” said Jeff Masters, director of meteorology for http://www.wunderground.com, in a statement from the union. “In fact, as the Earth gets warmer, and more moisture gets absorbed into the atmosphere, we are steadily loading the dice in favor of more extreme storms in all seasons, capable of causing greater impacts on society.”
He pointed to record and near-record storms in the Northeast and Midwest during the past two years as examples of what should be expected if Earth’s climate continues to warm.
But a northward shift of the jet stream, North America’s storm engine, could make it less likely for the Sierra Nevada snowpack to benefit from the heavier storms, Masters said.
Average snowpack in the Sierra Nevada has decreased by about 10 percent over the past century, according to a report from the California Department of Water Resources. The agency expects the mountain range’s snowpack to decrease by 25 to 40 percent by 2050, increasing stress on the state’s water system.
The downward trend doesn’t preclude big winters, just more extreme variations between wet and dry, according to the report.
“Average annual precipitation may show little change, but more intense wet and dry periods can be expected – more floods and more droughts,” according to the report.
The amount of rain or snow falling in the heaviest 1 percent of storms has risen nearly 20 percent since 1958, according to the Union of Concerned Scientists.
The Northeast U.S. has seen the greatest increase in extreme storms. The amount of precipitation falling in the largest one percent of storms has increased 67 percent in the region since 1958.
Over the same time period, the Western U.S. has seen a 9 percent increase in the amount of rain and snow failing during the heaviest storms, according to the data.
The trend should continue for decades, but snow will eventually turn to rain if the planet continues to heat up, Masters said.
Adam Jensen is a reporter with the Tahoe Daily Tribune, a sister publication of The Union.