How what was once the world's largest iceberg fell to pieces

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End of May off South Georgia: Only fragments of iceberg A76-A are still floating in the sea

Photo: NASA Earth Observatory

At times, the iceberg A-76 was considered the largest iceberg in the world. In May 2021, it broke off from the Filchner-Ronne Ice Shelf in Antarctica and then drifted into the open sea. At that time, it measured around 4320 square kilometres, making it larger than the holiday island of Mallorca.

But such record titles often only last for a short time for icebergs. Just one month later, in June 2021, A-76 broke into three new parts: A-76A, A-76B and A-76C. Since then, the title of "world's largest iceberg" has once again been borne by the chunk that had previously held it: A-23A, which broke off from the Filchner Ice Shelf in August 1986, but remained intact because it is anchored to the seabed, so to speak. It measures about 4000 square kilometers.

Current images from NASA now show how it went on with one of the A-76 descendants. The images provide clues as to how icebergs change over time on their journeys.

2400 kilometers in two years

In this satellite image of the week, A-76A can be seen in May 2023: still large and yet already badly shrunk. Meanwhile, the iceberg drifts near the remote island of South Georgia, about 2400 kilometers north of the Filchner-Ronne Ice Shelf, where it once came from. "It's impressive to imagine that he's gotten this far in about two years," Christopher Shuman, a glaciologist at the University of Maryland, said in a NASA news release.

In the Weddell Sea, the so-called Weddell Gyre ensures, among other things, that icebergs circle on a certain orbit and drift further and further away. Until October 2022, A-76A therefore spilled through the cold region of the planet. At that time, it was 135 kilometers long and 26 kilometers wide. This brought it to an area twice the size of London.

But then A-76A entered the Drake Passage and from there towards the South Atlantic into warmer waters – and the great melting began. Today there are only fragments, a fate that has already befallen other icebergs.

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