British island threatened by collision with world's largest iceberg

The British island of South Georgia, located in the Atlantic Ocean, is currently facing a significant threat due to a massive iceberg drifting towards it.

Measuring 49.5 miles (80 kilometres) long, weighing 1,000 billion tonnes, and covering 1,351 square miles (3,500 square kilometres), the iceberg in question, called A23a, is the largest in the world.

This gigantic mass broke away from the Filchner-Ronne Ice Shelf in Antarctica in 1986. It is also the oldest iceberg in the world.

Despite its unmatched weight, A23a is moving at a speed of 20 centimetres per second (7.87 inches per second or 0.72 kilometres per hour / 0.45 miles per hour), according to the British Antarctic Survey. It is being carried along by the Antarctic Circumpolar Current, the world's most powerful ocean current.

"These ice sheets start in the center of Antarctica and then float in the ocean. But now the speed at which this is happening has increased," said Andrew Meijers, an oceanographer interviewed by France Info.

The iceberg in question began moving in 2022 and is following "more or less a straight line" towards South Georgia, the scientist added.

Quoted by AFP, Raul Cordero, from the University of Santiago in Chile, however, estimates that the chances of collision with the island are "less than 50%". The island would tend to deflect the water, as ocean currents also do.

"These are very deep blocks of ice and usually, before approaching an island or a continent, they drift away due to the simple fact that near the island there is less depth," adds Argentine glaciologist Soledad Tiranti, quoted by TF1.

Still, the iceberg's arrival poses a serious threat to biodiversity on an island whose unique ecosystem is home to a large colony of king penguins, elephant seals and fur seals, Slate reports.

So many species could be threatened by this major shock to their environment. Indeed, the presence of huge blocks of ice could block access to the sea and prevent animals from feeding.

Slate recalls that in 2004, another iceberg "had already run aground on the island's continental shelf, leaving dead penguin chicks and baby seals on the beaches," while huge chunks of ice blocked access to normal feeding areas.

"If the iceberg gets stuck there, the animals might be forced to go around it. That would make them expend a lot more energy, which means fewer resources for the young and therefore increased mortality," says Andrew Meijers.

On the human side, the imminent arrival of the iceberg is also expected to have "impacts on fisheries," adds Mark Belchier, a marine ecologist who advises the South Georgia authorities, quoted by the BBC.

Furthermore, it is possible that the melting of A23a will lead to the formation of smaller icebergs that would remain dangerous for fishermen.

It is also expected to release a large amount of fresh water into the ocean, disrupting the local ecosystem. However, the nutrients it will bring into the water will support phytoplankton, a key food source for whales and other marine life.

While iceberg formation is a natural phenomenon, Meijers believes that the acceleration of their loss in Antarctica is likely caused by human-induced climate change.

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