Larsen B
The Larsen Ice Shelf is a long 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. In 2005, it covered approximately 78500 km2 of the earth's sea with exceptionally thick ice. 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 (or occupied) 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. A large section of the Larsen C shelf was reported to have broken away in July 2017.
The collapse of Larsen B has revealed a thriving chemotrophic ecosystem 800 m (half a mile) below the sea. The discovery was accidental. U.S. Antarctic Program scientists were in the north-western Weddell Sea investigating the sediment record in a deep glacial trough of roughly 1,000,000 square kilometres (390,000 sq mi) (twice the size of Texas or France). Methane and hydrogen sulfide associated with cold seeps is suspected as the source of the chemical energy powering the ecosystem. The area had been protected by the overlying ice sheet from debris and sediment which was seen to be building up on the white microbial mats after the breakup of the ice sheet. Clams were observed clustered about the vents.
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