Antarctic sea ice is at a record low, again End-shutdown

Sea ice extent around Antarctica has reached a record low level, for the second consecutive summer in the southern hemisphere.

This year’s low is 405,000 square miles below the average minimum extent of sea ice around Antarctica from 1981 to 2010, according to the National Snow and Ice Data Center. That amount of ice lost is equivalent to more than half of Alaska’s land area.

As Antarctic sea ice shrinks, it opens the way for waves to violently pound ice shelves slowing the flow of giant glaciers, some of which are already at risk of disintegrating and contributing significantly to sea level rise. , according to the NSIDC.

“Sea ice helps cushion large floating ice shelves and major outlet glaciers like Pine Island and Thwaites, and if these glaciers start a more rapid runaway loss of land ice, it could trigger a dramatic increase in the rates of sea ice rise.” sea ​​level before the end of this century,” says Julienne Stroeve, a scientist at the NSIDC, quoted in a release.

On February 6, 2015, the waters of the Amundsen Sea adjacent to Antarctica’s Thwaites and Pine Island glaciers were choked with sea ice, as seen by NASA’s Terra satellite. On February 1, 2023, when sea ice extent was reaching its summer minimum, the Aqua satellite saw very little. (Credit: NASA Worldview images, animation by Tom Yulsman)

The animation of the satellite images above shows a striking difference in the extent of sea ice adjacent to the Thwaites and Pine Island glaciers. An image shows ice-covered waters in February 2015, a year with above-average extent. The other one was caught in February this year, and the amount of sea ice is very small.

This year’s image also reveals a large iceberg below and to the right of center. The floe, designated B-22A, and currently about four times the size of New York City, broke off the Thwaites Glacier ice shelf back in March 2002. It then became stuck, or “landed,” on this surface. relatively shallow. part of the Amundsen Sea. For 20 years he was stuck there, until January, when it started to float.

Research has shown that when it ran aground, the iceberg played an important role in stabilizing the sea ice in the area. In some years, a band of firm sea ice (also called “fast” ice) remained anchored to the iceberg and ice shelf of Thwaites Glacier, helping to strengthen the glacier and slow its flow toward the sea. according to nasa.

doomsday is distress Night, but still…

With shrinking sea ice and another huge iceberg floating around, the situation is becoming more precarious for the glacier, which has been wildly exaggerated by the media. labelled the “Doomsday Glacier”. Although doomsday isn’t night (at least not the glacier!), Thwaites is spewing massive amounts of ice into the ocean, contributing about 4 percent of global sea level rise, about 1.5 inches per decade.

Changes in Antarctic ice mass between 2002 and 2020 are depicted in this visualization, with orange and red hues indicating areas that lost ice, while light blue hues show areas with increased ice. Ice mass loss has been greatest on the West Antarctic Ice Sheet. The Thwaites and Pine Island Glaciers, within the circled area, play an important role in the drainage of ice from this part of Antarctica to the sea. (Credit: NASA Visualization Studio animation screenshot. Annotation by Tom Yulsman)

Like a cork in a bottle, the Florida-sized Thwaites Glacier helps contain the West Antarctic Ice Sheet, one of two on the continent. But the cork’s grip has been weakening. This happened when the floating ice shelf extending from Thwaites Glacier over the water has been eaten away from below by warming seawater.

If the Thwaites Glacier were to disintegrate, the global sea level would rise by about two feet. That breakup, in turn, would destabilize much of the rest of the West Antarctic Ice Sheet. It has enough ice to raise the sea level by more than 10 feet.

Scientists call this a “collapse,” but that word is related to the geologic time scale. In reality, sea level rise would unfold over centuries.

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