Unpredictable journey is coming to an end: Largest iceberg in the world is crumbling rapidly

“Ice mountains are inherent dangerous,” said sea captain Simon Wallace At the beginning of this year against the BBC from the ship Pharos At the uninhabited island of South Georgia, while the largest iceberg in the world, as large as the province of South Holland, slowly came closer. “I would be very happy if he just missed us completely.”

Captain Wallace got his way. A23A, as the iceberg is called, lay on a collision course with the British island in the southern ocean for months, but has since been turned around the island and remained at a considerable distance.

Peter Bijl, Paleo-Oceanographer at Utrecht University, is not surprised that South Georgia was spared. “The fact that he would bump into that was never a realistic scenario for me.” There is a wide strip of shallow water around South Georgia, where the deep wall of ice would inevitably encounter.

No longer the biggest

Recent satellite images show that the iceberg has been crumbling rapidly for a few days, in the relatively warm water north of South Georgia. As a result, it is no longer the largest iceberg in the world. Experts expect that the remaining ice plate, the size of the province of Utrecht, will fall apart completely within a few weeks.

The relatively warm water north of South Georgia, with a temperature above freezing ensures that the iceberg from below melts faster.

But that is not the main cause for the fall, says Bijl: “The mountain comes in stormy areas, then the ice becomes unstable and cracks where melting water is created. That melt water freezes again and works like a wedge that splits the ice plateau. That is why it is crumbling so quickly.”

Unpredictable movements

Pieces as large as four hundred square kilometers float on the South Atlantic Ocean, where large icebergs do not often occur. In theory, that can be dangerous for inattentive skippers, says Bijl. “But nowadays many ships are equipped with radar. Moreover, the path of the smaller pieces on open ocean can be predicted.”

It is precisely in shallow area, where large icebergs with a deep keel scrap over the bottom, that icebergs can make dangerous unpredictable movements.

Zoom in

Almost forty years ago, A23A broke apart from Antarctica. The huge colossus then remained stuck for a long time on the Antarctic seabed until it started to float north in 2022, with an uncertain destination.

Yet it was inevitable that the IJsschots would fall apart somewhere on this latitude, says Bijl. “There were periods at the end of ice ages, some 12 thousand years ago, when icebergs came to the southern tip of South Africa. At that time the mountains were apparently even bigger and the water colder.”

For the South African coast, geologists found sand grains of the Antarctic continent that were carried with ice floes and remained behind. In the same way it was discovered that ice floes from Greenland once drove as southern as Madrid.

Sweet -water

The current global warming will ensure that more and larger ice floes break down, although the pace at which that happens is uncertain. If a lot of ice cream at the same time when melting water ends up in the southern ocean, it can further accelerate climate change. Sweet melt water is lighter than salt sea water, which means that the surface water is less likely to refresh. This makes the ocean less capable of the greenhouse gas co₂ to record.

A lot of research has already been done on this in the northern hemisphere, but much less in the southern ocean, says Bijl, who recently started an investigation into the subject. He is for this affiliated with Embracer, a network of climate scientists from six universities and knowledge institutions that investigate “feedbacks in the climate system”, or consequences of climate change that drive climate change further.

A single iceberg, even one as large as A23A, will not influence the climate. “That is like a drop in a glass of water, the ocean mixes very quickly. But a huge Armada, a war fleet of icebergs, is possible,” says Bijl. “In the blackest climate scenarios that is conceivable when the ice sheet falls apart.”

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