Snowpack in the Sierra Nevada last winter “was the lowest it has been in more than 500 years,” the Los Angeles Times reports, citing research published in the journal Nature Climate Change. Snowpack is a primary source of water for California. The melting snow provides about one-third of the state’s water, said the newspaper. Earlier this year, the snowpack was only 5-percent of the average recorded since monitoring began in the 1930s.
Valerie Trouet, a paleoclimatologist at the University of Arizona, and her colleagues compared data from snowpack reporting stations and studies of tree rings dating back to 1400 to estimate precipitation and temperatures. Data on temperatures indicate whether precipitation fell as rain or snow. “When researchers put all the data into a chronology, they saw how exceptional the 2015 snowfall was,” the Times said. “The chance that such a ‘snow drought’ would affect the entire Sierra Nevada more than once every 500 years was less than 5%, researchers concluded.” The scientists said their work helps put California’s four-year drought in perspective.