Strong winds have also hastened the sea ice decline, they reported. Researchers at the data center say the low sea ice has been due in part to a large band of warmer-than-normal air temperatures, which climbed to 2 degrees Celsius above average over the Ross Sea in November and December. "While the decline in Antarctic sea ice extent is always steep at this time of year, it has been unusually rapid this year," scientists at the National Snow and Ice Data Center reported in early January, "and at the end of December, Antarctic sea ice extent stood at the lowest in the 45-year satellite record." The calving comes amid record-low sea ice extent in Antarctica, where it is summer. Our science and operational teams continue to monitor the ice shelf in real-time to ensure it is safe, and to maintain the delivery of the science we undertake at Halley," Professor Dominic Hodgson a BAS glaciologist said in a news release. "This calving event has been expected and is part of the natural behavior of the Brunt Ice Shelf. The researchers say this event was expected and not a result of climate change. The iceberg is around 600 square miles, or 1550 square kilometers. The BAS Halley Research Station is located on the Brunt Ice Shelf and glaciologists say the research station is safe. Scientists first discovered significant cracks in the ice shelf a decade ago, but in the last two years there have been two major breaks. Story by Kathryn Hansen with information from Christopher Shuman (NASA GSFC/UMBC JCET).ANTARCTICA - An iceberg nearly the size of Greater London broke off the Brunt Ice Shelf in Antarctica on Sunday according to the British Antarctic Survey. Geological Survey and data © OpenStreetMap contributors via CC BY-SA 2.0. NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. But first it needs to be pushed offshore, and to date it does not appear to have moved very far. Most likely, it will eventually get caught up in the Weddell Gyre-similar to the fate of A-68. It also remains to be seen what will become of the new iceberg. “We’ll be closely watching that pinning point for changes to the larger Brunt Ice Shelf remnant.”
Antarctic ice shelf breaking off crack#
“The Halloween Crack may or may not be the first to respond,” Shuman said. Scientists are waiting to see how the complex structure responds to the recent calving. This section of the shelf is still holding on, but when it eventually breaks the berg will likely measure about 1700 square kilometers (660 square miles). After decades of growth and then a rapid acceleration in 2019, that rift appeared poised to spawn its own iceberg, prompting safety concerns for researchers “upstream” at the British Antarctic Survey’s Halley VI Research Station. “I would not have thought that this rift could go zipping across the northeast side of the Brunt Ice Shelf and cause a significant calving-all in a tiny fraction of the time it has taken Chasm 1 to extend toward the ice rumples from the south,” said Christopher Shuman, a University of Maryland, Baltimore County, glaciologist based at NASA’s Goddard Space Flight Center.Ĭhasm 1 is a separate rift located south of the ice rumples and the Halloween Crack. The rift that spawned the new berg appeared near the rumples in satellite images in September 2019, and it advanced across the ice shelf with remarkable speed during the austral summer of 2020-2021. For comparison, Iceberg A-68 was almost five times that size when it calved from the Larsen C Ice Shelf in 2017.Ī-74 broke from the ice shelf northeast of the McDonald Ice Rumples-an area where the flow of ice is impeded by an underwater formation that causes pressure waves, crevasses, and rifts to form at the surface.
That’s a large piece of ice for the Brunt Ice Shelf, but Antarctica is known for churning out some enormous bergs. Named A-74, the berg spans about 1270 square kilometers (490 square miles), or about twice the size of Chicago. On March 1, clouds were sparse enough for the Operational Land Imager (OLI) on Landsat 8 to acquire this natural-color image of the new iceberg. The break was first detected by GPS equipment on February 26, 2021, and then confirmed the next day with radar images from the European Space Agency’s Sentinel-1A satellite. Antarctica’s Brunt Ice Shelf finally calved a large iceberg in February 2021, two years after rifts opened rapidly across the ice and raised concerns about the shelf’s stability.
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