The cold snap in Europe that has killed more than 600 people and buried communities under record snow cover has had an entirely different impact in the Arctic, which is where you’d normally expect to find frigid weather at this time of year. In parts of the Far North, it has been unusually mild recently, and broad expanses of open water have emerged. This open water has raised questions about whether Arctic sea ice is declining even faster than before.
The open water, located in the Barents and Kara Seas, led one blogger to claim that the developments are “unprecedented” in the satellite era (since 1979), and that the winter buildup of Arctic sea ice had ground to a halt this year — possibly leading to a record low maximum sea ice extent for the winter season.
Sea ice concentration maps for Feb. 11 during the past several years. Arrows in bottom right images point to area of unusually open water. Click on image for a larger version. Credit: Univ. of Bremen/Climate Progress
Neven Acropolis, who writes the Arctic Sea Ice blog, wrote in a guest post for Climate Progress, “I think it’s safe to say that this is unprecedented ever since satellites started monitoring Arctic sea ice in 1979 . . . It’s almost as if the melting season has already started in the Barents and Kara Seas, more than two months earlier than normal.”
That’s not the case, though, according to sea ice expert Walt Meier of the National Snow and Ice Data Center (NSIDC) in Boulder, Colo. “I can’t say it’s unprecedented, but it’s certainly not something that we see regularly” during the winter, Meier said. “I wouldn’t be surprised if it’s happened before.”
According to Meier, sea ice tends to be present in most areas of the Arctic Ocean during winter unless warm water gets transported into the region, or winds push ice away from the coastline. In this case, persistent southwesterly winds associated with theunusual weather pattern are the prime suspect in causing the area of nearly ice-free waters nearNovaya Zemlya, a Russian island at the border between the Barents and Kara Seas. (For more background on what's been driving the cold snap, see my post from last week.)
Monthly average surface temperatures in Europe and the Arctic during February (left); and average monthly sea level pressure (right). Note the cold air and high pressure in Europe, and mild air and lower pressure in much of the Arctic. Click on image for a larger version. Credit: NCEP/NCAR.
“I think it’s mainly a wind effect due to the pressure system,” Meier said. “. . . It’s quite unusual that it’s such a large area and that it’s been there for at least a week right now, almost two weeks.” Areas of wind-driven open water are typically referred to aspolynyas, Meier said, although it’s not clear if the current situation meets the technical definition since the area of open water is so large.
The lack of sea ice in the Barents and Kara Seas may lead to a greater summertime loss of sea ice there, Meier said, because whatever ice manages to form before the melt season will be thin and therefore more susceptible to melting.
Meanwhile, on the Arctic’s Pacific side, there has been much more sea ice than average in the Bering Sea, associated with persistent northerly winds there. According to the most recent sea ice analysis from NSIDC, the Arctic-wide sea ice extent was much below average during January, despite the second-highest sea ice extent since 1979 in the Bering Sea. In fact, the drawdown of sea ice in the Barents and Kara Seas held January sea ice growth to the lower level in the satellite record, NSIDC researchers stated.