OSU study: snowpack declines across the West
A new study that includes work by Oregon State University climate researchers found that snowpack has declined significantly at monitoring sites around the West.
According to the study, during the past 103 years the snowpack has declined between 15 percent and 30 percent, about the amount to fill Lake Mead, the West's largest manmade reservoir.
The study's authors say the loss of water could impact municipal, industrial and agricultural uses and animal habitat.
Results of the study are being published Friday, March 2, in "NPJ Climate and Atmospheric Science," a Nature publication.
"It is a bigger decline than we had expected," said Philip Mote, director of OSU's Oregon Climate Change Research Institute and lead author on the study. "In many lower-elevation sites, what used to fall as snow is now rain. Upper elevations have not been affected nearly as much, but most states don't have that much area at 7,000-plus feet.
"The solution isn't in infrastructure. New reservoirs could not be built fast enough to offset the loss of snow storage — and we don't have a lot of capacity left for that kind of storage. It comes down to managing what we have in the best possible ways."
Researchers attribute the snowpack decline to warmer temperatures, not a lack of precipitation. The study considered data from 1,766 sites in the West, mostly from the U.S. Department of Agriculture's Natural Resources Conservation Service and the California Department of Water Resources. The study looked at measurements taken on April 1, which historically has been the high point for snowpack in most areas. Other measurements were also checked for Jan. 1, Feb. 1, March 1 and May 1.
"We found declining trends in all months, states and climates, but the impacts are the largest in the spring, in Pacific states, and in locations with mild winter climates," said Mote, one of 12 lead authors on a chapter of the fifth Intergovernmental Panel on Climate Change report looking at the cryosphere, which is comprised of snow, river and lake ice, sea ice, glaciers, ice sheets and frozen ground.
According to the study:
• California had the highest number of positive snowpack trends since 1955, but lingering drought during the past decade erased most of those gains and snowpack declines still dominated;
• Most of the other western states had only one or two sites that reported increases in snowpack;
• Eastern Oregon and Northern Nevada had the most significant decrease in snowpack.
"The amount of water in the snowpack of the western United States is roughly equivalent to all of the stored water in the largest reservoirs of those states," Mote said. "We've pretty much spent a century building up those water supplies at the same time the natural supply of snowpack is dwindling."
Mote said snowpack levels in most of the West for 2017-18 thus far are lower than average – a function of continued warming temperatures and the presence of a La Niña event, which typically results in warmer and drier conditions in most southwestern states.