Extreme weather has become the new normal – be it precipitation, drought, wind, heat or cold. The question of how the shrinking layer of Arctic sea ice contributed to one of these changes has sparked lively discussions in recent years. Researchers have proposed that a weakened jet stream driven by disappearing Arctic sea ice could play a major role in extreme winter events such as the descending polar vortex that hit North America earlier this year. But the idea didn’t hold up well in the light of more recent evidence.
But now researchers have established a direct link between extreme winter weather and sea ice loss. The winter storm ‘Beast of the East’ of 2018 hit Europe with record-breaking snowfall and low temperatures. And possibly as much as 88 percent of that snowfall came from the increased evaporation of the Barents Sea.
The working hypothesis is that Arctic sea ice acts as a cap for Arctic waters, limiting evaporation. Less sea ice and warmer Arctic temperatures mean more evaporation, possibly explaining the increased severity of winter storms like the Beast of the East. Until now, it has been difficult to measure direct evidence linking sea ice loss to extreme European winters, but recent technological advances make this a little less challenging.
Secrets of the North
With freezing temperatures, 24-hour winter darkness and, well, not much land, the Arctic is one of the world’s most hostile research environments. To date, much of the region’s direct data has been collected by hands-on research boats, but these expeditions are expensive and limited in where and when they can be used.
Instead, this latest study used recent technology – an isotope and gas concentration analyzer – that automatically collects real-time data at the impressive frequency of nearly one reading per second. While the researchers didn’t install the instrument in the farthest reaches of the North Pole, they added one at a weather station in Pallas-Yllästunturi National Park, in northern Finland, just a few hundred kilometers from the Norwegian Sea.
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The observation station of the Finnish Meteorological Institute in Pallas-Yllästunturi National Park, Finland. Sampling antennas protruding from the roof captured the water vapor emanating from the Barents Sea as it traveled southward into Europe.
K. Mustonen.
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Hannah Bailey, the lead author of the study, manually collects snow samples in Finland during the Arctic winter outbreak.
Hannah Bailey
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Eric Klein, study co-author, performs routine maintenance on the Picarro water vapor isotope analyzer (named “R2D2”) in Pallas, Finland.
Hannah Bailey
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The sea ice cover, which acts as a lid to the ocean surface, was particularly low in the Barents Sea in 2018.
J. Welker
They installed the instrument in late 2017 and since then they have been able to detect the naturally occurring stable isotopes in water vapor, i.e. hydrogen and oxygen. Two of these isotopes, 18O and 2H, have been widely used for monitoring hydrological processes over the past 70 years. Because these isotopes are slightly heavier, they evaporate less quickly, creating unique isotope ‘fingerprints’ for phase transitions such as evaporation, cloud formation, rain and snow. This has made it possible to trace the origins of storm systems – and the research team placed this instrument just in time for a whopper of a storm.
The beast
Within months of installing the instrument, the team noticed a massive isotopic peak in March 2018, just as the Beast of the East arrived in Europe. The researchers traced this peak in vapor to unusually high amounts of evaporation from the Barents Sea, which was warmer and more ice-free than historical standards.
“The data from our study represents the first ‘true measurements’ that prove that sea ice loss through enhanced evaporation contributes to extreme mid-latitude snowfall,” said lead author Hannah Bailey. “Until now, scientists have explored the link between Arctic sea ice loss and extreme snowfall using climate models, and without this technology we use, it simply wouldn’t be possible to capture these kinds of natural events and processes in real time. . “
The team also combined satellite data and modeling to calculate that up to 88 percent of the Beast storm’s snow – 140 billion tons – could come from the Barents Sea.
Less ice, more snowfall
The team focused on the Barents Sea because it is a literal “hotspot” of declining sea ice in the Arctic. The maximum sea ice level in March has fallen 54 percent there since 1979. Using historical satellite observations and atmospheric models, the team confirmed that smaller amounts of Barents Sea ice over the past 30 years have regularly correlated with higher evaporation and heavier March snowfalls in North America. Europe.
This evidence also suggests that this trend may increase with further sea ice loss in the Barents Sea, which some researchers have predicted will be ice-free by 2061-2088. The team hopes to set up a network of these isotope monitoring tools across the Arctic – both on ships and on land – to better measure these changes in the future.
“There is scientific consensus that the Arctic sea ice decline has implications for latitude weather, but there is a lack of consensus between the models used to investigate these processes,” said Bailey. “There is tremendous potential for atmospheric vapor isotope data to improve weather forecasting as well as to help predict extreme weather events affecting society.”
Nature Geoscience, 2021. DOI: 10.1038 / s41561-021-00719-y (About DOIs).
KED Coan is a freelance journalist who writes climate and environmental stories at Ars Technica. She has a Ph.D. in chemistry and chemical biology.