The image is strong. A gigantic thousand-year-old sea ice shelf of some 1,200 square kilometers in size – twice the size of the city of Madrid – has collapsed into the Conger Glacier in eastern Antarctica, disintegrating into thousands of icebergs that are already sailing through the Antarctic Ocean . The largest, called C8, was 320 square kilometers when it collapsed, although it has ended up fracturing in the following days. Now, the largest icebergs are sailing at about 65 kilometers per day in a west-northwest direction, as reported by the United States National Ice Centerwhich analyzes NASA satellite images.
The event, in an area of the continent that was believed to be much more stable than the western one, took place coinciding with a heat wave in which the usual temperatures in that place for a month of March were exceeded by 40ºC, although no climbs above zero degrees. Scientists suspect that what happened is related to this increase, although they point out that more information must be added to the images pending analysis.
In any case, this platform, which is fed by both the Conger Glacier and the neighboring Glenzer Glacier, seemed to be intact at the beginning of the month, so the collapse has occurred in just two weeks. In statements collected by NASA, glaciologist Christopher Shuman acknowledges that “it has been a blowout [un suceso que no se esperaba de forma tan repentina]”, although it was known that it had been losing a square kilometer of ice a day for two years, much more than what it lost before that date.
Already at the beginning of March, a giant iceberg of 144 square kilometers had broken off the sea platform in front of the Glenzer Glacier, which eventually broke off and disconnected the mainland from nearby Bowman Island. As it was no longer anchored to land, the ice shelf was destabilized throughout the area, a situation that days later coincided with rising temperatures. Fernando Bohoyo, a polar scientist at the Geological and Mining Institute of Spain (IGME) and a specialist in ocean currents, recalls how in that area “it had already been detected that the surface waters are warming up; by circulating under the floating ice that comes out through the glaciers from the polar cap, it destabilizes it, until it breaks the anchors, as has happened”. Precisely how these anchors work is part of his research project with the scientist Carlota Escutia.
The concern is great among researchers because it is the first time that a collapse of such a dimension has occurred in one of the ice shelves of eastern Antarctica, although there have been very important ones in the western one. The largest, on the Larsen platform, in the Weddell Sea, which is the largest on the continent. The area called Larsen A disintegrated in 1995, Larsen B almost completely disappeared in 2002 and Larsen C suffered a detachment in 2017 of 5,700 square kilometers, in the A68 iceberg that has been considered missing after fragmenting in April last year. in the South Georgia Islands. “These ice shelves on the ocean act as a plug so that the interior ice does not advance rapidly, so it will be necessary to see how the speed of this loss increases, which as it is interior ice, not frozen sea ice, contributes to the net increase in sea level,” says Bohoyo.
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Although the ice shelf and glaciers are relatively small, they are notable for the novelty of the location. “All previous collapses have taken place in West Antarctica, not East Antarctica, which until recently was considered relatively stable,” Catherine Walker of the Woods Hole Oceanographic Institution and NASA said in a statement. “This is somewhat of a dress rehearsal of what we might expect from other, more massive ice shelves if they continue to melt and destabilize. Then we really will be past the tipping point in terms of slowing sea level rise.”
It should be remembered that previous studies have already indicated that about 75% of the Antarctic ice shelves that are distributed around the continent have receded during the last 50 years and that if we reach a global warming of 2ºC over the pre-industrial era and this is prolonged over time, much of the ice in that large area of eastern Antarctica will melt, which alone could raise global sea level by up to 53 meters.
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