Sierra Nevada snowpack hit a 500-year low in 2015
SACRAMENTO – In California Gov. Jerry Brown stood in a snowless Sierra Nevada meadow on April 1 and ordered unprecedented water restrictions because of the drought, it was the first spring in 75 years of observation that the area lacked snow.
Now, six months later, researchers say this year’s record-low snowpack may be far more historic — and ominous — than previously realized.
“We were expecting that 2015 would be extreme, but not like this,” said senior study author Valerie Trouet, a paleoclimatologist at the University of Arizona.
The paper is the latest in a series of studies that have sought to characterize the depth of California’s four-year drought and place it in a broader context.
While those studies have used tree ring records and other proxies to estimate past temperature, precipitation and dryness, this is the first to examine Sierra Nevada snowfall specifically.
Snowpack is a key factor in California’s water supply: Melting Sierra Nevada snow helps to replenish and sustain state reservoirs and provides the state with roughly a third of its water. Because of this, researchers and state officials began monitoring snowpack in the 1930s, and have established 108 measuring stations throughout the Sierra Nevada.
This spring, researchers found that the April 1 snow water equivalent was only 5% of average since monitoring began. In the case of the meadow in Phillips — where Brown ordered water use reductions — spring snowpack usually reached a height of 5 1/2 feet during that time of year.