The world’s largest and oldest iceberg, designated A23a, has run aground in shallow water approximately 50 miles off the remote British island of South Georgia, in the South Atlantic. The island is home to millions of penguins and seals. The iceberg, which is larger than the state of Rhode Island, appears to be stuck and should start breaking up on the island’s southwest shores.
The good news is that A23a did not directly collide with the remote island as had been previously feared, which had the potential to devastate the penguin and seal populations by blocking their access to food.
In 2004, the island was not as lucky. The huge berg A38 grounded at South Georgia leaving countless penguin chicks and seal pups dead on local beaches.
While other sea life, such as coral, sea slugs, sponges, and other organic creatures may be damaged by the crushing ice, scientists say that huge amounts of nutrients locked inside the A23a’s ice could create an explosion of life in the ocean as the ice melts.
The BBC quotes Prof Nadine Johnston from the British Antarctic Survey saying, “It’s like dropping a nutrient bomb into the middle of an empty desert.”
In addition to being currently the largest iceberg in Antarctic waters, A23a is also one of the oldest. In 1986, the massive iceberg calved off West Antarctica’s Filchner-Ronne Ice Shelf and immediately grounded on the floor of the Weddell Sea, where it remained hard aground for almost four decades until it broke free in late 2023.
Then, instead of drifting off on the Antarctic Circumpolar Current into “iceberg alley,” A23a became stuck in a massive oceanic eddy just north of South Orkney Islands, turning in an anti-clockwise direction by about 15 degrees a day, where it remained for almost a year before escaping the vortex in mid-December.
“The future of all icebergs is that they will die. It’s very surprising to see that A23a has lasted this long and only lost about a quarter of its area,” said Prof Huw Griffiths, speaking to BBC News from the Sir David Attenborough polar research ship currently in Antarctica.
On Saturday the 300m tall ice colossus struck the shallow continental shelf about 50 miles (80km) from land and now appears to be firmly lodged.
“It’s probably going to stay more or less where it is until chunks break off,” says Prof Andrew Meijers from the British Antarctic Survey.