A-68

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Crack in Area C of the Larsen Ice Shelf in November 2016

A-68 (also A68 ) is the name of an iceberg that broke away from Area C of the Larsen Ice Shelf on the east coast of the Antarctic Peninsula between July 10 and 12, 2017 .

Emergence

The four areas A to D of the Larsen Ice Shelf
The iceberg A-68 on an image of the Thermal Infrared Sensor (TIRS) of the Landsat-8 satellite on July 20, 2017. Cold ice surfaces appear gray to black, warmer sea water white.

As early as 2014, the researchers noticed a crack in the large ice surface that had grown over the years. In the end, a 20 kilometer long bridge held the area together, but it also broke. From January 2017 on, due to the instability, it was expected that the surface could loosen. Between July 10 and 12, 2017, the iceberg finally broke away from the Larsen Ice Shelf in Area C. The iceberg has been one of the largest of its kind for the past three decades and the third largest ever observed by satellite.

development

With a length of 175 kilometers, a width of 50 kilometers and an estimated thickness of 200 m and an estimated mass of around one trillion tons, the iceberg is floating in the sea off West Antarctica . Researchers expect that the 5800 km² iceberg (roughly equivalent to the area of ​​the canton of Bern or twice the area of ​​the Saarland ) will take up course in a north-easterly direction to the South Georgia archipelago and then melt; this group of islands is about 1400 kilometers east of the Argentine coast.

Until the beginning of August 2017, the iceberg had not moved far and was still in the same bay. The pressure from sea ice is still holding the iceberg in place. Only the distance to the ice shelf had changed slightly on the south side and is up to 5 kilometers there. It is expected that locomotion will not take place until six months later in the Antarctic summer.

Satellite images a few days after its creation already indicated that the iceberg was breaking apart. At the beginning of August 2017 it became known that smaller icebergs had already broken off from A-68.

On September 16, 2017, satellite images from the European Space Agency (ESA) showed that a gap had formed between the iceberg and the Larsen C Ice Shelf. At the greatest distance, on the south side of the fracture point, it was 18 kilometers.

By the beginning of July 2018, the iceberg was about 50 kilometers from the breaking point. In the following two months it turned and at the beginning of September jutted perpendicular to the edge of the ice shelf into the Weddel Sea.

At the beginning of February 2020, the A-68 iceberg moved roughly northwards into the open seas of the Southern Ocean and could be located on satellite images.

On April 23, 2020, part of the iceberg broke off. The partial iceberg is designated A-68C. It has an area of ​​175 km² (roughly equivalent to the area of ​​Saarbrücken or 3.5 times the area of ​​the city of Bern).

consequences

When the iceberg, which is more than 100 meters thick, broke off, the area of ​​area C of the ice shelf shrank by a tenth. The original area was around 50,000 km 2 .

It is feared that Area C of the Larsen Ice Shelf will destabilize. At the beginning of August 2017, other smaller icebergs had already broken off.

A-68 (bottom left), South Orkney Islands (top right)

The sea ​​level will not rise directly due to the now melting iceberg, since an iceberg floats on the water and after melting results in exactly the mass of water that it previously displaced. The sea level could rise slightly, however, because meltwater from glaciers on land can now get into the sea more quickly. If all the glaciers were to melt that were previously prevented by Larsen C from flowing into the sea, the sea level would rise about 10 cm.

It does not pose a threat to shipping as it can be detected early on by radar due to its size and mass .

See also

Individual evidence

  1. ↑ What makes the giant iceberg A68 so scary. In: n-tv , July 13, 2017, accessed on July 13, 2017.
  2. ↑ a b c d e f g Gigantic iceberg is drifting north-east. In: Norddeutscher Rundfunk , July 12, 2017, accessed on July 13, 2017.
  3. ↑ a b c d Giant iceberg broken off in Antarctica . In: Westdeutscher Rundfunk , July 12, 2017, accessed on July 13, 2017.
  4. ↑ a b The third largest iceberg ever observed by satellite is stuck on the ice shelf. In: Der Standard Onlineausgabe, August 10, 2017, 9:41 am, accessed on August 10, 2017.
  5. ↑ What happened next to the giant Larsen C iceberg? , Nicola Davis, The Guardian, August 2, 2017
  6. ↑ a b c d Giant iceberg accompanied by kilometer-long "dwarfs" In: Der Standard online edition, August 2, 2017, 12:17 pm, accessed on August 10, 2017.
  7. ^ Bryan Kahn: The Larsen C. Iceberg Is Already Cracking Up. . In: Climate Central , July 19, 2017, accessed July 22, 2017.
  8. ↑ Icy giant A68 is floating in the sea. In: Mitteldeutscher Rundfunk online edition MDR Wissen , September 21, 2017, 10:00 am, accessed on September 21, 2017.
  9. ↑ "The glaciers have withdrawn" , in: Süddeutsche Zeitung , interview with Daniela Jansen, online edition v. July 10, 2018, 7:53 am, retrieved July 18, 2018 at 1:56 pm UTC + 01: 00.
  10. ^ Adrian Luckman: Iceberg A68 escapes into the Weddell Gyre . Animation in "Adrian's glacier gallery", accessed on September 6, 2018 (English)
  11. ↑ World's biggest iceberg makes a run for it. BBC News Online, February 5, 2020, accessed June 23, 2020 .
  12. ↑ A-68, largest iceberg in the world drifting into the open sea. EuroNews Online, February 12, 2020, accessed June 23, 2020 .
  13. ↑ Is the world's biggest iceberg about to break up? BBC News Online, April 23, 2020, accessed June 23, 2020 .
  14. ↑ Gigantic iceberg floating in the Antarctic. In: welt.de. July 12, 2017. Retrieved July 14, 2017 .
  15. ↑ Huge iceberg has broken away from Antarctica. In: Frankfurter Allgemeine Zeitung , July 12, 2017, accessed on July 14, 2017.

Coordinates: 67 ° 45 ′ 33.8 ″  S , 60 ° 28 ′ 7.5 ″  W.