Imminent Larsen C Ice Shelf Collapse

Imminent Larsen C Ice Shelf Collapse.

The Larsen Ice Shelf is a long, fringing ice shelf in the northwest part of the Weddell Sea, extending along the east coast of the Antarctic Peninsula from Cape Longing to the area just southward of Hearst Island. It is named for Captain Carl Anton Larsen, the master of the Norwegian whaling vessel Jason, who sailed along the ice front as far as 68°10′ South during December 1893. In finer detail, the Larsen Ice Shelf is a series of shelves that occupy distinct embayments along the coast. From north to south, the segments are called Larsen A (the smallest), Larsen B, and Larsen C (the largest) by researchers who work in the area. Further south, Larsen D and the much smaller Larsen E, F and G are also named. The breakup of the ice shelf since the mid 1990s has been widely reported, with the collapse of Larsen B in 2002 being particularly dramatic. Larsen C is the fourth largest ice shelf in Antarctica, with an area of about 50,000 km2 (19,000 sq mi). On 1 May 2017 members of the Antarctic research group Project MIDAS, a British Antarctic research project observing the ever-growing crack, reported that satellite images showed a new crack, around 9 miles long (15 kilometers), branching off the main crack approximately six miles behind the previous tip, heading toward the ice front. Scientists with Swansea University in the UK say the crack lengthened 11 miles from 25 May to 31 May, and that less than 8 miles of ice is all that prevents the birth of an enormous iceberg. “The rift tip appears also to have turned significantly towards the ice front, indicating that the time of calving is probably very close,” Adrian Luckman and Martin O’Leary wrote on Wednesday in a blog post for the Impact of Melt on Ice Shelf Dynamics and Stability project, or MIDAS. “There appears to be very little to prevent the iceberg from breaking away completely.” The larger swath of the Larsen C ice shelf that sits behind the soon-to-calve iceberg “will be less stable than it was prior to the rift” and may rapidly disintegrate like a neighbouring ice shelf did in 2002. Since the ice shelf is already floating, its departure from Antarctica would not affect global sea levels. But a number of glaciers discharge onto it from the lands behind the ice shelf, and therefore might flow faster if it breaks away from the continent. If all the ice that the Larsen C shelf currently holds back were to enter the sea, it is estimated that global waters would rise by 10 cm (4 in).

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