At that point, a significant amount of ice could ooze from glaciers into the ocean. Researchers from Europe predict major changes to the shelf would happen only if it loses 55 percent of its ice. Not everyone is convinced that Larsen C will fall apart completely. This technique allows researchers to track much tinier changes in the crack compared with standard black-and-white radar images. The image is an interferogram, which shows a pattern formed when the radar signals from the two images are superimposed. Story continues after graphic LINING UP Two radar images taken April 7 and April 14 with the European Space Agency’s Sentinel-1 Earth-observing satellites reveal the growing crack (red) in Antarctica’s Larsen C ice shelf. Larsen C’s calving, he says, “may simply be a natural event that would have happened regardless of human activity.” “Not all ice-related stories have a clear global warming origin,” Luckman notes. Still, the calving event that feeds a potential collapse may be hard to pin on climate change. Some computer simulations suggest Larsen C could suffer the same fate, possibly within a few years to decades, Luckman says. In 2014, researchers concluded the collapse of Larsen B was the result of warming ( SN: 10/18/14, p. But in the last two decades, ice shelves have instead continued to lose ice until collapsing, probably as a result of rising temperatures due to climate change, researchers suspect. But calving or the collapse of an ice shelf allows glaciers and ice streams further inland to flow into the ocean, which can contribute to sea level rise.Ĭalving of icebergs is common, and over several decades, the shelves usually recover to their original size. Since these shelves float on the water, calving icebergs don’t directly raise sea level. Antarctica’s ice shelves act as buttresses, helping to slow the flow of the continent’s ice into the ocean. “Glaciologists are keen to see how Larsen C will react,” says Luckman.Ī complete collapse of Larsen C could have implications for sea level rise. The same thing happened to the neighboring Larsen B ice shelf in 2002, after it calved a Rhode Island-sized iceberg ( SN: 3/30/02, p. “The calving event is significant because it is likely a precursor to something much bigger, potentially the collapse of the whole Larsen C ice shelf,” Booth says. “Maps will need to be redrawn.” And that could be the least of the trouble ahead, says Adam Booth, a geophysicist at the University of Leeds in England also with Project MIDAS. The ice loss dramatically alters the landscape of Larsen C, Luckman notes. Then, sometime between July 10 and July 12, it finally reached the water, allowing the huge hunk of ice to splinter off into the sea. By July 6, the crack had come within 5 kilometers of the edge of the ice. Yet the vigil lasted nearly two more weeks. Added Luckman, also in a tweet: “The remaining ice is strained near to breaking point.” “It won’t be long now,” Project Midas tweeted June 30. Then, in late June, the outer part of the ice shelf picked up speed, putting new pressure on the crack and the entire shelf. The crack grew another 17 kilometers between May 25 and May 31 - at times traveling parallel to the edge and ultimately putting it within 13 kilometers of the ice front. “The remaining ice is strained near to breaking point,” Project MIDAS glaciologist Adrian Luckman tweeted in late June. Satellite images show the ice’s movement tripled in speed to more than 10 meters per day in the waning days of June, the fastest it had ever been recorded. In the days before it broke off, Larsen C’s outer ice shelf gained momentum.
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