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For the first time since records began, the main Arctic sea ice nursery in Siberia has yet to begin to freeze in late October.
The delayed annual freeze in the Laptev Sea has been caused by abnormally prolonged heat in northern Russia and the intrusion of Atlantic waters, say climate scientists warning of possible side effects in the polar region.
Ocean temperatures in the area recently rose to more than 5 ° C above average, following a record heat wave and the unusually early decline in sea ice last winter.
Trapped heat takes a long time to dissipate into the atmosphere, even at this time of year when the sun looms over the horizon for little more than an hour or two a day.
Graphs of the extent of sea ice in the Laptev Sea, generally showing a healthy seasonal pulse, appear to have flat lines. As a result, there is a record amount of open sea in the Arctic.
“The lack of freezing so far this fall is unprecedented in the Arctic region of Siberia,” said Zachary Labe, a postdoctoral researcher at Colorado State University. He says this is in line with the expected impact of man-made climate change.
“2020 is another consistent year with a rapidly changing Arctic. Without a systematic reduction in greenhouse gases, the probability of our first ‘ice-free’ summer will continue to rise in the mid-21st century, ‘he wrote in an email to The Guardian.
This year’s Siberian heat wave was triggered at least 600 times more by industrial and agricultural emissions, according to a previous study.
Warmer air temperature isn’t the only factor slowing down ice formation. Climate change is also pushing gentler Atlantic currents into the Arctic and breaking the usual stratification between warm, deep waters and the cold surface. This also makes ice formation difficult.
“This continues with a very short streak. The last 14 years, from 2007 to 2020, are the lowest 14 years in the satellite record as of 1979, ”said Walt Meier, senior research scientist at the US National Snow and Ice Data Center. much of the old ice in the Arctic is now disappearing, leaving thinner seasonal ice. In general, the average thickness is half what it was in the 1980s.
The downward trend is likely to continue until the Arctic has its first ice-free summer, Meier said. Data and models suggest this will occur between 2030 and 2050. “It is a question of when, not if,” he added.
Scientists worry that delayed freezing may amplify reactions that accelerate the ice sheet’s decline. It is already well known that a smaller ice sheet means less white area to reflect the sun’s heat back into space. But this is not the only reason the Arctic is warming more than twice as fast as the world average.
The Laptev Sea is known as the birthplace of ice, which forms along the coast in early winter, then moves west, transporting nutrients through the Arctic, before breaking up in the spring in the Straits. of Fram between Greenland and Svalbard. If the ice forms late in Laptev, it will be thinner and therefore more likely to melt before reaching the Strait of Fram. This could mean fewer nutrients for Arctic plankton, which will then have a reduced ability to extract carbon dioxide from the atmosphere.
More open sea also means more turbulence in the upper layer of the Arctic Ocean, which draws more warm water from the depths.
Dr. Stefan Hendricks, a sea ice physicist at the Alfred Wegener Institute, said the sea ice trends are grim but not surprising. “It is more frustrating than shocking. This has been predicted for a long time, but there has been little substantial response from decision makers. “
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