As a general rule, we tend to associate global warming with less snow and ice. But the impacts of our planet’s carbon-fueled fever aren’t always simple, and a new study suggests a double whammy of rising temperatures and natural climactic variability yielded a major uptick in snowfall in south-central Alaska since the 19th century.
It’s no secret that snowfall in Alaska is changing. Many parts of the state have seen record-low snowfall in recent winters, while other places, mostly along the southern coast, have received a boost. Earlier this month, Alaska’s Thompson Pass reported one of the highest rates of snowfall ever recorded on the planet.
In parts of southern Alaska where snowfall is on the rise, scientists have ascribed the change to a strengthening of the Aleutian Low—a low pressure system that governs the advection of warm, moist air into southern Alaska—since the mid-20th century. But go back much further in time, and our weather records start to get fuzzy.
To put this recent shift in a longer-term perspective, a team of researchers at Dartmouth, the University of Maine, and the University of New Hampshire scaled Denali National Park’s Mt. Hunter and drilled deep into the glacial peak, collecting ice cores that are nearly 700 feet long and preserve 1,200-years worth of regional climactic history.
By analyzing the distinct icy layers laid down by seasonal precipitation, the researchers learned that snowfall on the mountain from 1950 to 2013 is the highest it’s been over the entire record. The change isn’t subtle. Rates of snowfall over Mt. Hunter have roughly doubled since the mid-19th century, according to the paper published this week in Nature Scientific Reports.
“Over the last thirty years the average snowfall is about 18 feet per year,” lead study author Dominic Winski told Earther. “During pre-industrial times, our best guess was that it was a little less than [nine feet].”
A sudden uptick in snowfall coinciding with the onset of the Industrial Revolution certainly raises the question of climate change’s involvement. After all, Central Alaska has been warming much faster than the planet as a whole—two to three degree Celsius since 1950—and a warmer atmosphere is capable of holding more water and dumping more rain (or snow).
But warming alone isn’t enough to account for the dramatic snowfall rise, leaving the researchers to conclude it’s “very likely that that a strengthening Aleutian Low is responsible for the majority of the accumulation increase observed in the Mt. Hunter ice core.”
However, climate change might be playing a sneaky role there, too. The researchers call out other studies suggesting that rising sea surface temperatures in the western Pacific and Indian Ocean could be strengthening the Aleutian Low via “teleconnections,” basically—anomalies that propagate throughout the upper atmosphere. The authors note that in their own dataset, higher rates of snowfall accumulation on Mt. Hunter correlate with warmer periods in the Western Pacific.
It’s worth emphasizing that this is basically the first data point to support a hypothesis right now. But at least one outside expert, National Snow and Ice Data Center director Mark Serreze, found the study interesting, if not too surprising. “There is natural climate variability and forced change, and the two are intertwined,” he told Earther.
As for the future, it’s hard to say whether rates of snowfall in southern Alaska will continue to increase in the future, although Winski says he would “at least expect for this out of the ordinary precipitation to persist.” But, he added, “it’s hard to tell what other factors we haven’t thought about yet that’ll either accelerate or counteract this precipitation increase.”
The ecological impacts are likewise, for now, a question mark. Although Winski did note one sobering fact: All the extra snowfall hasn’t been enough to offset rapid glacial melt occurring due to hotter summers.
“In spite of all this extra snowfall, glaciers have still been losing mass at significant rates,” he said.