2023 Arctic Melt Season Begins 1 Million KM2 Below Average; More On 2007 Tipping Point
As Arctic sea ice reached a total winter maximum coverage that is again far below average, research has revealed how this ice is vulnerable to extreme weather arriving from more southerly parts of the globe — and how it might never recover. Arctic sea ice, which expands through the fall and winter, reached an annual maximum extent of 14.62 million square kilometers (5.64 million square miles) on March 6, according to the National Snow and Ice Data Center (NSIDC). That means Arctic sea ice is starting the summer melt season more than a million square kilometers below average. The maximum, which came almost a week earlier than normal, is the fifth-lowest in the 45-year satellite record.
Antarctic sea ice extent has been in an even sorrier state, setting a record melt season low in February for the second year in a row, in what may be a sign that global warming will soon impact that polar system just as it’s been impacting Arctic sea ice. The combined sea ice extent around both poles hit a record low in January. While ice reflects most solar radiation, open water absorbs it, accelerating global warming in what is known as the ice-albedo feedback.
With warmer El Niño conditions expected to return later this year, significantly raising global temperature, the north polar ice cap could break its own record for lowest extent this fall. But it’s impossible to make any predictions, since highly variable summer weather patterns tend to have the biggest impact on sea ice melt, said NSIDC director Mark Serreze.
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“We found that the decline of the thick ice type was not a gradual process, but a sudden and distinct change that occurred around 2007,” Sumata said. A major melt event in 2005, and the dramatic drop in sea ice extent in 2007, left open water in the “ice factories” north of Alaska and Siberia that began absorbing more of the sun’s warmth in an ice-albedo feedback. Finding itself in hot water, the ice was never able to recover: It became more vulnerable to summer melt and less able to grow back in the winter. The average thickness of all but the youngest ice passing through the Fram Strait decreased from 2.7 meters to 1.7 meters (5.6 feet) after 2007.
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https://news.mongabay.com/2023/03/southern-atmospheric-rivers-are-melting-the-arctic-sea-ice-it-may-never-recover-study/
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