Tuesday, September 15, 2015

California's Sierra Nevada snowpack shrinks to a 500-year low

[CSMonitor] California's Sierra Nevada mountains haven't had this little snowpack since the days of Christopher Columbus.
That's the finding of a new study released Monday indicating this year the state has seen its lowest snowpack in 500 years, and climate change may cause greater water shortages in the already drought-stricken, wildfire-ravaged state.
This past spring, the mountain range had just 5 percent of the average snowpack recorded in the second half of the 20th century, and scientists said the findings indicated "the 2015 low is unprecedented in the context of the past 500 years."
The study found that the depth of snow at 108 measuring stations in the Sierra Nevada on April 1 was just 2.3 inches in "snow water equivalent" - the depth of the water if the snow melted - against an average 27.5 inches from 1930-2014.
“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, in an interview with the Los Angeles Times.
According to the newspaper, the new research is the latest attempt in a series of studies that seek to find scope and broader context for California’s four-year drought. Snowpack in the Sierra Nevada range, which runs along the spine of the Golden State, provides about 30 percent of California’s annual water supply.
The “low” finding was based on records of snowfall and temperatures gathered from annual growth rings of blue oaks and other trees in the mountain range, resulting in some reservations about extremes in past centuries.
The scientists also said the uncertainties in tree ring data indicated that a few years, mainly in the 16th century, might have had snowpack lows even lower than the 2015 numbers. Read More