According to a new analysis conducted by a team of scientists from the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI) and the University of Bremen, there is currently less sea ice in the Antarctic than at any time since the beginning of satellite measurements four decades ago. In early February 2023, only 2.2 million square kilometers of the Southern Ocean were covered with ice.
“On 8 February 2023, at 2.20 million square kilometers, the Antarctic sea ice extent had already dropped below the previous record minimum from 2022 (2.27 million square kilometers on 24 February 2022). Since the sea ice melting in the Antarctic will most likely continue in the second half of the month, we can’t say yet when the record low will be reached or how much more sea ice will melt between now and then,” explained Christian Haas, an expert in Sea Ice Physics at AWI.
“The rapid decline in sea ice over the past six years is quite remarkable, since the ice cover hardly changed at all in the thirty-five years before. It is still unclear whether what we are seeing is the beginning of a rapid end to summer sea ice in the Antarctic, or if it is merely the beginning of a new phase characterized by low but still stable sea ice cover in the summer.”
This rapid melting has progressed substantially from December 2022, particularly in the Bellingshausen and Amundsen Seas in the West Antarctic, with the latter being currently nearly ice-free. “I have never seen such an extreme, ice-free situation here before. The continental shelf, an area the size of Germany, is now completely ice-free,” said Karsten Gohl, an AWI geophysicist leading the expedition of the research vessel Polarstern. “Though these conditions are advantageous for our vessel-based fieldwork, it is still troubling to consider how quickly this change has taken place.”
According to the experts, this intense melting may be caused by unusually high temperatures to the west and east of the Antarctic Peninsula (cc. 1.5 degrees Celsius above the long-term average). Moreover, the Southern Annular Mode (SAM) is now in a strongly positive phase, intensifying the westerly winds and causing them to contract toward the Antarctic. As a result, upwelling of circumpolar deep water on the continental shelf intensifies too, promoting sea-ice retreat and the melting of ice shelves.
Currently, researchers are exploring the geological evolution of the West Antarctic Ice Sheet, in order to estimate its future development in the face of rapid climate change.
More detailed analyses of Antarctica’s situation can be found at the Sea Ice Portal.
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