World’s biggest iceberg begins to get smaller

Iceberg A-68 size has visibly decreased over the past few years. In 2020 a chunk of ice broke from the iceberg, measuring 175 square kilometres and this footage was taken by the European Space Agency’s satellite called Sentinel-1.

It calved from the Larsen C Ice Shelf in July 2017. The Larsen ice shelf originally covered an area of 85,000 square kilometres, but now occupies an area of 67,000 square kilometres. It is a series of shelves; which segments are called from the Larsen A (the smallest) to the Larsen C (the largest) by the researchers working in the area.

Larsen C, from which the A-68 broke from, was the fourth largest ice shelf in Antarctica in July 2017. In 2016 the scientists noticed the growing rift, which was running along the ice shelf being 110 kilometres length, 91m in width and 500m depth. As the year passed, the rift extended noticeably, where only 20km of unbroken ice remained. This calved fragment was predicted to be one of the largest icebergs recorded, being 350m thick and covering an area of 5,000 square kilometres. Another crack was noticed on May 2017, being around 15km long and the process of calving of the enormous iceberg was close, as the crack lengthened 18km during May towards the ice front. Another sign of calving was seen in June 2017, as even though the iceberg remained attached to the ice shelf, its outer end was noted to be moving at the high speed. In the beginning of July the rift branched few times, multiple rift tips within 5km of the ice edge were seen and this was stated by the Project MIDAS blog report- UK-based Antarctic research project monitoring the results of the warming climate on the Larsen C ice shelf. On 12 July 2017 they announced the large portion being broken from the main ice shelf- A-68. The event was described in the BBC news article by Matt McGrath from 6 January 2017:

“As is true of all floating ice shelves, A68’s departure from Antarctica had no immediate effect on global sea levels. However, a number of glaciers discharge onto the shelf from the land behind it, and they may now flow faster due to reduced support from the ice shelf. If all the ice that the Larsen C shelf currently holds back were to enter the sea, global waters would rise by an estimated 10 cm.”

A-68, which was the part of the Larsen Ice Shelf, poses questions whether calving was a geographical, natural occurrence or the result of climate change. It may be believed that the climate warming helped with separating the iceberg. On the Project MIDAS website, it was noted the structure of the ice is changing, as the recent warming during summer caused large melts ponds to form on Larsen C. One of the posts on their website from July 9, 2018 is called “Iceberg A-68 one year on”, where the iceberg was compared to being: “One quarter the size of Wales, and weighing more than a trillion tonnes”, classified as the sixth largest iceberg since records began. There was also added satellite image animation which showed that the iceberg haven’t drifted far and that in May 2018 few pieces of the iceberg shattered off due to the tides and winds as well as more shallow water near Bawden Ice Rise. In 2020 a chunk of ice broke from the iceberg, measuring 175 square kilometres-footage was taken by the European Space Agency’s satellite called Sentinel-1. In the article from Live

Science website by Brandon Specktor, the size of the A-68 before splitting from Antarctica was compared to the current size- more than 2,300 square miles, which decided on the title of the biggest world’s iceberg, shrinked down to 2,000 square metres over the period of three years. The size of the glacier decreased, and it is assumed that the iceberg might slowly begin to split into smaller pieces as the time passes. Even though the size of the iceberg is enormous, its thinness makes it likely to split. This event was more broadly described in the article from April 28 by TimesTravel website saying:

“That thinness makes A-68 especially vulnerable to the strong currents and increasingly warm temperatures that await it north of Antarctica. Further splits will likely follow, Luckman said, and A-68 as we know it will be no more. However, he added, the berg will likely live on for many years through the constituent chunks that crack off its edges, many of which will be large enough to earn their own names. That includes the chunk that broke off on Thursday; according to a tweet from Luckman, the new-born iceberg will likely become known as A-68c. We look forward to watching its slow march toward the iceberg afterlife.”

The mentioned A-68c is one of the parts that broke off and was large enough to be given names as well as A-68A and A-68B. On the NASA MODIS website, there is an explanation of the Antarctic ice bergs being named, saying: “Antarctic ice bergs are named, rather unromantically, from the Antarctic quadrant in which they were originally sighted, then a sequential number, then, if the iceberg breaks, a sequential letter.” A-68C is the second to calve from A-68, which was announced in late April 2020. As the iceberg drifts north into warm waters, it may soon be divided into small fragments that are weakened by the temperature and form fragile structure. Mail Online article from 6 February 2020 by Jonathan Chadwick says: “Rising waters and air temperatures caused by global warming are triggering instabilities along the coasts of Antarctica and Greenland, accelerating melting and increasing the rates of calving.”

By Julita Waleskiewicz