Rain on Arctic Snow

Grist: "Rain comes to the Arctic, with a cascade of troubling changes." In August of 2021, unexpected rain fell on the 10,551-foot summit of the Greenland ice cap, triggering an epic meltdown and a more than 2,000-foot retreat of the snow line. Back in the fall of 2008 it 'rained for four days as the air temperature rose by 30 degrees Celsius (54 degrees Fahrenheit), close to and above the freezing point.' This warmed the summit's firn [not fern but pronounced the same] layer, snow transitioning to ice, by between 11 and 42ºF (6 and 23ºC). "The rainwater and surface melt that followed penetrated the firn by as much as 20 feet before refreezing, creating a barrier that would alter the flow of meltwater the following year." Each time a rain-on-snow event happens...the structure of the firn layer is altered, and it becomes a bit more susceptible to impacts from the next melting event. "Twenty years ago, annual precipitation in the Arctic rangedfrom about 10 inches in southern areas to as few as 2 inches or less in the far north." As the Arctic warms up at least 3 times faster than the world as a whole, 'melting sea ice and more open water will, according to a recent study, bring up to 60 percent more precipitation in coming decades, with more rain falling than snow in many places.' "The precipitation will trigger more flooding; an acceleration in permafrost thaw; profound changes to water quality; more landslides and snow avalanches; more misery for Arctic animals, many of which are already in precipitous decline due to the shifting climate; and serious challenges for the Indigenous peoples who depend on those animals." Thunderstorms happening where previously rare, including in Siberia. Surface crevassing, which allows water to enter into the interior of the icecap, is accelerating, thanks to rapid melting. And Alaska's rainfall up 17% over last century, 'in one case, sent 180 million tons of rock into a narrow fjord, generating a tsunami that reached 633 feet high — one of the highest tsunamis ever recorded worldwide.' I could go on, but already this sounds like a disaster movie, except that it's really happening.