Iceberg A-68

Iceberg A-68 calved from the Larsen C Ice Shelf in July 2017.[1][2][3] With a surface area of 5,800 square kilometres, twice the size of Luxembourg, larger than Delaware and weighing one trillion tonnes,[4] it is one of the largest recorded icebergs, the largest being B-15 which measured 11,000 square kilometres before breaking up. The calving of A-68 reduced the overall size of the Larsen C shelf by 12 percent.[4]

Iceberg A-68 on July 20, 2017
The drift of Iceberg A-68a from 1 May 2018 to 26 August 2018.

There is no projected path at this point; however, historical data shows many icebergs broken off from the Antarctic Peninsula reach the South Georgia and the South Sandwich Islands.[5]

The name "A-68" was assigned by the US National Ice Center.

History and recent developments

A-68 was part of Larsen C, a section of the Larsen Ice Shelf. The scientific community is divided whether the calving is the result of climate change, or merely a natural occurrence.[6] Scientists found the crack beginning to form in November 2016, and others suggested that it might have broken off as early as a decade ago. According to scientists observing the iceberg's path, A-68 "didn't just break through in one clean shot, [but] it formed a lace-network of cracks first."[4]

Satellite images from ESA and the European Union's Copernicus Program show that the iceberg is splintering, forming more icebergs in the process.[7]

Scientists are looking into the possibility of the ice shelf collapsing as a result of the split with A-68, or whether the iceberg was the "cork" for Larsen C that allows ice to flow more freely into the sea, thereby contributing to rising sea levels.[8]

Since November 2017, satellite images show A-68 is slowly drifting northward, with a widening gap to the main shelf. The gap was approximately five kilometers wide and contained a thin layer of loose, floating ice and a cluster of over 11 'smaller' bergs, one much larger than the rest.

A British expedition on RRS James Clark Ross intended to sample the marine life at A-68 cleavage line in March 2018, but had to turn back due to thick sea ice.[9]

In July 2018 A-68 started to drift northwards.[10]

On 9 December 2019 MS Expedition was the first ship to sight A-68 . On 6 February 2020 A-68 began to move into open waters.[11] On 10 March 2020 MV World Explorer spotted A-68a in position 61°45′S 51°33′W .

On 23 April 2020 a chunk measuring about 175 sq km broke free from the iceberg.[12]

  • Radar imagery from ESA's Sentinel-1B taken on 12 July 2017, showing the complete break
  • Iceberg A-68 on 12 July 2017
  • Close-up of Iceberg A-68 on 20 July 2017
  • Closeup of the iceberg A-68 on 9th December 2019
  • Second closeup of the iceberg A-68 on 9th December 2019
  • MS World Explorer at Iceberg A-68a with a spy-hopping Humpback Whale in the Weddell Sea

References
  1. "Larsen C calves trillion ton iceberg". Project MIDAS. 12 July 2017. Retrieved 12 July 2017.
  2. "Giant iceberg splits from Antarctic". BBC. 12 July 2017.
  3. "Massive iceberg breaks away from Antarctica". CNN. 12 July 2017. Retrieved 13 July 2017.
  4. Davis, Nicola (2 August 2017). "What happened next to the giant Larsen C iceberg?". The Guardian. ISSN 0261-3077. Retrieved 2 August 2017.
  5. Mosher, Dave (12 July 2017). "Where Antarctic iceberg from Larsen C shelf might go in Southern Ocean". Business Insider. Retrieved 21 July 2017.
  6. Luckman, Adrian. "I've studied Larsen C and its giant iceberg for years – it's not a simple story of climate change". The Conversation. Retrieved 2 August 2017.
  7. Dvorsky, George. "Antarctica's Massive Iceberg Is Starting to Disintegrate". Gizmodo. Retrieved 2 August 2017.
  8. Becker, Rachel (2 August 2017). "Cracks are still spreading where that massive Antarctic iceberg broke free". The Verge. Retrieved 2 August 2017.
  9. Amos, Jonathan (2 March 2018). "Mission to giant A-68 berg thwarted by sea-ice". BBC News. Retrieved 12 April 2018.
  10. Brandon, Mark. "A trillion tonnes of ice on the move: Iceberg A68A". Mallemaroking. Retrieved 31 August 2018.
  11. https://www.bbc.com/news/science-environment-51389690
  12. Amos, Jonathan (23 April 2020). "Is the world's biggest iceberg about to break up?". BBC News. Retrieved 28 April 2020.
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