States across the western US are facing record low snowpack levels in the middle of the winter season. The snowpack crisis, which could mean a drier, more wildfire-prone summer, is coming as states are racing unsuccessfully against a deadline to agree on terms to share water in the Colorado River Basin, the source of water for 40 million people across seven states in the West.
“Barring a genuinely miraculous turnaround” in the remainder of the winter, says Daniel Swain, a climate scientist at the University of California Agriculture and Natural Resources, the low snowpack “has the potential to worsen both the ecological and political crisis on the Colorado Basin, and then also produce really adverse wildfire conditions in some parts of the West.”
Data provided by the US Department of Agriculture show that as of February 12, snowpack was at less than half its normal level in areas across nine Western states—some of the lowest levels seen in decades. It’s common for a particular basin or small area of the West to have low snowpack at this time of year. What’s worrisome, Swain says, is how widespread the snow drought is, stretching in a swath from the bottom of Washington to much of Arizona and New Mexico, and touching as far east as Colorado.
“The numbers are really, really bad,” Swain says. “If this were November, they might be less meaningful. We’re not in November—we’re heading toward mid-February. The normal numbers are pretty high. To be at half of them means that, in absolute terms, the deficit is large.”
As much of the East Coast has frozen in the first weeks of the year, many Western states are experiencing some of their warmest winters on record: Parts of Colorado saw temperatures close to 80 degrees Fahrenheit at the start of this week. While precipitation has remained steady in many states—parts of Washington even saw disastrous flooding in December—it’s simply not cold enough in many areas for snow to fall or stay in snowpack.
A study released last year by researchers at Dartmouth found that climate change has led to a reduction in snowpack levels across the northern hemisphere over the past 40 years. A snowpack deficit has some worrisome implications for the West for the rest of the year. Forests with low snowpack dry out faster, and are less resilient against wildfire when the hot season comes. (Wildfire-ravaged forests may also, in turn, be less prepared to keep snowpack around; some recent research has shown that in areas that have recently been burned, snow melts faster than other places.)
Much of the water supply for the West, including the crucial Colorado River Basin, is set during the winter. Snowpack that accumulates in the cold months melts in the spring; in years with healthy snowpack levels, that water makes its way into streams and reservoirs. Current conditions pose a threat to this dynamic.
“In some places, we don’t have a traditional drought—what we’ve got is a snow drought, where precipitation has been near or above average, but where record warmth has really been driving just a complete decimation of the existing snowpack,” says Swain. The warmth in other areas, he says, has “caused the precipitation that has fallen—which in some cases has been reasonably abundant—to fall as rain, even at 7,000 and 9,000 feet elevation.”
Swain says it’s still early enough in the season that there could be some significant storms to help replenish snow levels in some areas. “The problem is that we’ve accumulated such a large deficit right now—even if we have near or somewhat above average snowfall for the next few weeks, that might just sort of keep pace with the usual accumulation for the rest of February, without really erasing the accumulated deficit,” he says.
