Atmospheric rivers are long, narrow bands of concentrated moisture that transport water vapor and heat from warm oceanic regions to colder high-latitude areas. While these systems have been primarily associated with accelerating Arctic ice melt, a major event in March 2022 demonstrated their potential to counteract ice loss. During this event, an atmospheric river deposited 16 billion tons of snow on Greenland, reducing the annual ice loss by approximately 8%. This substantial snowfall also refreshed the winter snowpack, increasing its reflectivity (albedo) and delaying the seasonal ice melt by nearly two weeks.
Alun Hubbard, a field glaciologist affiliated with the University of Oulu, Finland, and the Arctic University of Tromso, Norway, has been studying the relationship between precipitation and ice melt in Greenland for over a decade.
"Sadly, the Greenland Ice Sheet won't be saved by atmospheric rivers," said Hubbard. "But what we see in this new study is that, contrary to prevailing opinions, under the right conditions atmospheric rivers might not be all bad news."
The study was published in Geophysical Research Letters, an open-access AGU journal that features high-impact, concise research with broad scientific implications.
With climate change expected to intensify atmospheric rivers in terms of frequency and magnitude, understanding their impact on Greenland is crucial.
Hannah Bailey, a geochemist at the University of Oulu and lead author of the study, was in Svalbard during the March 2022 storm, where prolonged rainfall turned the snowpack into slush, halting fieldwork. This led her to investigate how the storm had influenced Greenland's ice sheet.
A year later, Bailey and Hubbard conducted fieldwork in southeastern Greenland, at an altitude of about 2,000 meters (6,562 feet), where snow accumulates persistently, transforming into firn and eventually glacial ice. The researchers extracted a 15-meter-long firn core, capturing nearly a decade of snow deposition. By analyzing oxygen isotopes and density variations, Bailey determined accumulation rates and correlated them with weather data.
"Using high-elevation firn core sampling and isotopic analysis allowed us to pinpoint the extraordinary snowfall from this atmospheric river," said Bailey. "It's a rare opportunity to directly link such an event to Greenland ice sheet surface mass balance and dynamics."
"I was surprised by just how much snow was dumped on the ice sheet over such a short period," Hubbard said. "I thought it'd be a minute amount, but it's a gobsmacking contribution to Greenland's annual ice mass."
Beyond adding mass, the fresh snow delayed summer melting by about 11 days, even in the presence of higher-than-average spring temperatures.
Further research is needed to determine the long-term impact of atmospheric rivers on Greenland's ice sheet. If global temperatures continue to rise, future precipitation in Greenland may fall primarily as rain, intensifying ice loss.
"Atmospheric rivers have a double-edged role in shaping Greenland's, as well as the wider Arctic's, futures," Bailey noted.
Research Report:Snow Mass Recharge of the Greenland Ice Sheet Fueled by Intense Atmospheric River
Related Links
University of Oulu
Beyond the Ice Age
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