When 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.
In a paper published Monday in the journal Nature Climate Change, scientists estimate that recent Sierra Nevada snowpack was the lowest its been in over 500 years.
“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.