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.
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.
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.”
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.”