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Over the past four decades, snowpack has shrunk in watersheds across the Northern Hemisphere as a result of climate change. That is the top-level and sobering finding of a new report out of Nature last week. And for the Western U.S., it is a serious one.
It can’t be emphasized enough what less snow means for a region that has already pushed watersheds beyond their limits. Snowpack is the primary source for many rivers in the West. And mountains serve as a natural reservoir. They store snow as it accumulates during the winter. In the spring, that snow steadily runs off into creeks and rivers. When there is less snow, there is less water in rivers. This is a major issue especially in the West where historic over-appropriation and overuse has created a situation where supply of water exceeds demand for water, including in good years.
As the researchers from Dartmouth write, “Together, our findings portend serious water-availability challenges in basins where snowmelt runoff constitutes a major component of the water supply portfolio. Improving our understanding of where and how climate change has and will affect snow water resources is vital to informing the difficult water resource management decisions that a less snowy future will require.”
The study was picked up by outlets across the country, and the L.A. Times’ Haley Smith published an in-depth and excellent summary of the research findings:
“Between 1981 and 2020, dozens of river basins have seen a significant decline in snow water equivalent, or the amount of water contained in the snow, due to human-caused climate change, according to a study published Wednesday in the journal Nature.
The sharpest drops — between 10% and 20% per decade — were in the Southwestern and Northeastern United States, as well as Central and Eastern Europe.
…
Many of the snow-dependent watersheds now find themselves on the precipice of a threshold the researchers dubbed a ‘snow-loss cliff,’ or a point at which marginal temperature increases imply larger and larger snow losses to come. The inflection point occurs when average winter temperatures in a watershed are warmer than 17 degrees.”
The Associated Press also had thorough coverage of the study.
Over the past decade, numerous scientific studies have documented the effects that climate change is having on the snowpack in the Western U.S. and the overall water cycle. And all of us who rely on that water have watched it play out in real-time.
Snowpack matters for the water supply. But it is engrained into ecological systems in many more ways, interacting with wildlife, vegetation, groundwater and even wildfire.
Will there still be big wet years like last year? Of course. The Times quoted one of the study authors who said “a year where California has near-record or record snowpack is entirely consistent with a larger picture from global warming.” But the study is a reminder of a future that is coming, and in many cases one that has already arrived.
Not only do warming temperatures raise major questions about the future of snow in critical areas like the Sierra Nevada and the Colorado River Basin, but the climate also affects the reliability and efficiency of how snow actually travels to rivers. When soils and the environment are dry, less water can make it to the river. A statistic that stuck with me is this one, which I heard at a Colorado River conference in 2021: That year, the snowpack was measured at ~85% but the river was at ~30% of average, a finding that the commissioner of the Bureau of Reclamation called a “staggering difference.”
Cities, agricultural lands, economies and communities across the globe have assumed a water cycle that is changing. And it raises major questions. Do we have a policy (let alone physical) infrastructure to deal with a future of less snow and certainty? How do we create it quickly while ensuring that we do not repeat the mistakes of the past?
All of this is made harder by manmade systems that were already unsteady to begin with. Many watersheds (like the Colorado River) are over-appropriated, meaning that there are more rights to use water than there is, on average, water to go around. Not to mention that warming temperatures, on their own, can increase demand for water.
I’m not sure what the answers are here, and they are likely to vary in every place, but actively planning for a future with shrinking snow seems more important than ever.
Nevada water rights buyback program looks for sellers: The Elko Daily Free Press reports that “ten willing property owners so far have offered to sell water rights for retirement in central Nevada and the Humboldt River Basin.” The deadline to come to apply for the program is Jan. 22. Wrote about this for the Nevada Independent last year.
Legal guardians of nature: “A town in Colorado has appointed two legal guardians to act on behalf of nature—in this case, a section of Boulder Creek and its watershed situated within the town of Nederland,” InsideClimateNews reports.
Five things to watch in Southern Nevada water, from the Las Vegas Review-Journal.
Uranium mining starts near the Grand Canyon, via The Arizona Republic.
A global view: “The United Nations estimates that 1.84 billion people worldwide, or nearly a quarter of humanity, were living under drought in 2022 and 2023, the vast majority in low- and middle-income countries,” the New York Times reported last week.