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article imageEarlier snow melt in North America will impact water resources

By Karen Graham     Apr 6, 2021 in Science
More snow is melting during winter across western North America, a concerning trend that could impact everything from ski conditions to fire danger and agriculture, according to a new analysis of 40 years of data.
A University of Colorado Boulder analysis of 40 years of data from 1,065 automated stations in western Canada and the United States found that more snow is melting earlier in the year. Their findings were published March 5, 2021, in Nature Climate Change.
The researchers found that since the late 1970s, the boundary between winter and spring has been slowly disappearing, with one-third of the 1,065 snow measurement stations from the Mexican border to the Alaskan Arctic recording increasing winter snowmelt.
"Particularly in cold mountain environments, snow accumulates over the winter -- it grows and grows -- and gets to a point where it reaches a maximum depth before melt starts in the spring," said Keith Musselman, lead author on the study, and research associate at the Institute of Arctic and Alpine Research (INSTAAR) at the University of Colorado Boulder.
May 4  2016 footage of Siphon Creek fire in BC. Early snowmelt  coupled with hotter than normal temp...
May 4, 2016 footage of Siphon Creek fire in BC. Early snowmelt, coupled with hotter than normal temperatures increases the possibility of a record fire season.
Vancouver Sun online
Although many stations recorded a significant increase in snowmelt mostly during November and March, the researchers found that melt was increasing in all the cold months, from October to March, according to Science Daily.
Interestingly, the research showed that snowmelt before April 1 has increased at nearly half (42 percent) of more than 600 stations in western North America, by an average of 3.5 percent per decade.
"Historically, water managers use the date of April 1 to distinguish winter and spring, but this distinction is becoming increasingly blurred as melt increases during the winter," said Noah Molotch, a co-author on the study, associate professor of geography, and fellow at INSTAAR.
The headwaters of the San Joaquin River start as snowmelt in the high reaches of the Sierra Nevada M...
The headwaters of the San Joaquin River start as snowmelt in the high reaches of the Sierra Nevada Mountains.
Implications for water resources
Besides the bad news regarding ski conditions, including fewer pristine powder days, and crustier snow for skiers, the impacts of the increased snowmelt will be important for water resource planners.
Snow is the primary source of water and streamflow in western North America. In the West, snowy mountains act like water towers, reserving water up high until it melts, making it available to lower elevations that need it during the summer, like a natural drip irrigation system, according to Colorado University Boulder.
“That slow trickle of meltwater that reliably occurs over the dry season is something that we have built our entire water infrastructure on in the West,” said Musselman. “We rely very heavily on that water that comes down our rivers and streams in the warm season of July and August.”
The decline in water elevation has exposed a white band of mineralized rock around the shoreline. Th...
The decline in water elevation has exposed a white band of mineralized rock around the shoreline. The declining reservoir level has also exposed portions of Hoover Dam’s four intake towers, two on the right side and two on the left side. These intake towers channel water from Lake Mead into penstocks that serve Hoover Dam's 17 hydroelectric generators.
Department of the Interior
And the shift of the snowmelt to spring instead of the later summer months could have a great impact on agriculture and food security, reports CTV News Canada.
Snow monitoring stations have been an underutilized source of data. This study is the first of its kind to examine all 1,065 stations in western North America.
“These automated stations can be really helpful to understand potential climate change impacts on our resources,” said Musselman. “Their observations are consistent with what our climate models are suggesting will continue to happen.”
More about Snow melt, North America, cryospheric science, hydrology, Water resources
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