Larsen Ice Shelf

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Coordinates: 67 ° 30 ′  S , 62 ° 30 ′  W

Location of the Larsen Ice Shelf on the east coast of the Antarctic Peninsula - from north to south the four areas Larsen 'A' to Larsen 'D'

The Larsen Ice Shelf is an elongated ice shelf in the western part of the Weddell Sea , which stretches on the east coast of the Antarctic Peninsula from the Jason Peninsula to the Smith Peninsula . It is named after the Norwegian captain Carl Anton Larsen , who sailed along the ice shelf with the Jason in December 1893 .

The Larsen Ice Shelf is divided into four sections, three of which can be assigned to different large bays. These sections are named Larsen A, Larsen B, Larsen C, and Larsen D (from north to south).

Larsen A is assigned to the smallest and northernmost of the large bays, Larsen B is assigned to the adjacent middle and Larsen C is assigned to the adjacent largest and southernmost of these bays. Larsen D is closest to the South Pole and is not assigned to a single bay, but represents an elongated section with many small bays lined up one behind the other and increasingly southern bays.

Decay due to global warming

Until the late 1980s, the Larsen Ice Shelf reached from the Prince Gustav Canal to Cape Fiske over more than ten degrees of latitude and had a size of 103,400 km². Larsen A disbanded in January 1995 and Larsen B in February 2002. Larsen-C is also in danger of shattering after a large iceberg split off in July 2017.

In January 2005 the area of ​​the ice shelf was 78,515 km². The disintegration is unusual in that ice shelves usually get smaller by “calving” icebergs or melting on their surface. The breakup was a result of global warming ; In the area of ​​the Larsen Ice Shelf, a temperature increase of around 0.5 ° C per decade has been observed since the 1940s, when regular measurements began.

Larsen B.

The Larsen B Ice Shelf stretched from Robertson Island in the north to the Jason Peninsula in the south. Its dissolution was noted between January 31st and March 7th, 2002 when it broke off with an ice sheet of 3,250 square kilometers. By then, the ice shelf had been stable for over 10,000 years throughout the Holocene . In contrast, the Larsen A Ice Shelf had only existed for 4,000 years. The collapse of Larsen-B led to an accelerated outflow of the ice streams behind it into the sea. After the collapse, up to eight times higher flow rates were measured.

The detachment of the ice shelf made a chemotrophic ecosystem feeding on the sediment of the sea accessible, which mainly consists of a mat of bacteria and mussels.

Larsen C

Rift in the Larsen C Shelf (November 2016)
Image of the ESA Earth observation satellite Sentinel-1 from Larsen C on July 12, 2017

On July 12, 2017, an approximately 5,800 km² piece of the Larsen C Shelf broke off and reduced its area by around 12%; the fragment with a mass of around one trillion tons was given the designation A-68 . It is one of the largest icebergs observed so far. After the termination, the destabilization threatens the dissolution of Larsen C.

The breaking off of icebergs is a sign of the increasing destabilization of the Antarctic ice and the associated rise in sea levels . Although Larsen C, as an ice shelf that floats on the sea, does not itself contribute to sea level rise, the dissolution of the ice shelves accelerates the drainage of land-based glaciers. At the moment, the various Antarctic ice shelves such as Larsen C still act as a kind of barrier wall that strongly slows the flow of Antarctic glaciers into the sea. The complete melting of the Antarctic Peninsula, on which Larsen C is located, would theoretically result in a global sea level rise of up to 20 centimeters. In all of the Antarctic glaciers, water is stored for a theoretical global rise in sea level of around 58 meters.

Others

The breaking off of the Larsen Ice Shelf is also mentioned in the end-of-time film The Day After Tomorrow .

Web links

Commons : Larsen Ice Shelf  - Collection of images, videos and audio files
 Wikinews: Larsen C - Signs of Climate Change?  - message

Individual evidence

  1. ^ A b Hernán de Angelis: Larsen Ice Shelf . In: Beau Riffenburgh (Ed.): Encyclopedia of the Antarctic , Routledge, New York and London 2007, pp. 585–587, ISBN 0-415-97024-5 (English)
  2. ↑ In the Antarctic, a huge sheet of ice threatens to break. In: Frankfurter Allgemeine Zeitung , December 3, 2016.
  3. ↑ a b Huge iceberg has broken away from Antarctica. In: Frankfurter Allgemeine Zeitung . July 12, 2017. Retrieved July 12, 2017 .
  4. ↑ E. Rignot, G. Casassa, P. Gogineni, W. Krabill, A. Rivera, R. Thomas: Accelerated ice discharge from the Antarctic Peninsula Following the collapse of the Larsen B ice shelf.  ( Page no longer available , search in web archives ) In: Geophysical Research Letters 31, 2004, L18401, doi : 10.1029 / 2004GL020697 ( PDF ; 447 kB).@1@ 2Template: Toter Link / web.ist.utl.pt
  5. ↑ E. Rignot, G. Casassa, P. Gogineni, W. Krabill, A. Rivera, and R. Thomas: Accelerated ice discharge from the Antarctic Peninsula Following the collapse of the Larsen B ice shelf. ResearchGate , September 22, 2004, accessed on June 14, 2019 (English, also includes PDF).
  6. ↑ Eugene Domack, Scott Ishman, Amy Leventer, Sean Sylva, Veronica Willmott, Bruce Huber: A Chemotrophic ecosystem found beneath Antarctic Ice Shelf. In: EOS, Transactions American Geophysical Union. 86 (29), 2005, pp. 269 + 271-272, doi : 10.1029 / 2005EO290001 (PDF).
  7. ^ Martin O'Leary, Adrian Luckman and Project MIDAS: Larsen C calves trillion ton iceberg. July 12, 2017, accessed July 12, 2017 .
  8. ^ Paul Voosen: Delaware-sized iceberg splits from Antarctica . In: Science . June 12, 2017 (English, sciencemag.org ).
  9. ^ P. Fretwell et al .: Bedmap2: improved ice bed, surface and thickness datasets for Antarctica . In: The Cryosphere . No. 7 , 2013, p. 375–393 , doi : 10.5194 / tc-7-375-2013 (English).