The world’s biggest iceberg, named A23a, has come to a standstill as it appears to have run aground in shallow waters off the remote island of South Georgia after drifting around the Southern Ocean near Antarctica since 2020.
A23a, weighing 1.1 trillion tons, has come to a stop off the remote British territorial island in the southern Atlantic Ocean, according to a statement from the British Antarctic Survey (BAS) on Tuesday.
Dr. Andrew Meijers, an oceanographer at BAS, said the trillion-ton slab of ice — called a megaberg — could “break up, disperse and melt.”
“If the iceberg stays grounded, we don’t expect it to significantly affect the local wildlife of South Georgia…. Commercial fisheries have been disrupted in the past however, and as the berg breaks into smaller pieces, this might make fishing operations in the area both more difficult and potentially hazardous,” Meijers said.
He added that it “will be interesting to see what will happen” with A23a.
“From a scientific perspective we are keen to see how the iceberg will affect the local ecosystem. Nutrients stirred up by the grounding and from its melt may boost food availability for the whole regional ecosystem, including for charismatic penguins and seals,” he said.
“We have several ongoing studies looking at exactly how ‘megabergs’ influence the ocean circulation, its chemistry, and the ecosystems they support.”
A23a calved from the Filchner Ice Shelf in Antarctica in 1986 and remained grounded on the seabed in the Weddell Sea for over 30 years, according to the BAS.
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In January, Meijers referred to the megaberg as “a Game of Thrones style wall of ice that towers above the ship.”
“The iceberg itself is colossal and it stretches from horizon to horizon,” Meijers told The Associated Press at the time.
“With some waves breaking against it and if you get a bit of sunshine coming through, it’s really dramatic.”
An aerial view of iceberg A23a on Nov. 24, 2024 in the South Atlantic Ocean near South Georgia and the South Sandwich Islands.
UK MOD Crown Copyright via Getty Images
For every bit of the iceberg above the water’s surface, there’s 10 times more below, Meijers said.
He predicted in January that in two to four weeks, the iceberg would approach South Georgia, where the water gets shallow, and would wedge itself in or slide past.
“South Georgia is an amazingly ecologically rich island. It’s a breeding ground for a huge number of penguins, millions of penguins and seals,” Meijers said. “There’s lots of pups and chicks and they’re all still dependent on their parents.”
The parents go out quite a way into the water and forage. Icebergs can block pathways to their food, making the adults swim farther, burning more energy, bringing back less to the babies. That “unfortunately can dramatically increase mortality rates. And it has happened in the past,” Meijers said.
In 2020, another massive iceberg broke off of Antarctica and was on a potential collision course with South Georgia, home to thousands of penguins and seals.
The iceberg, known as A68-A, looked like a giant hand pointing a finger. It measured 150 kilometres long and 48 kilometres wide, with a surface area nearly as large as Prince Edward Island. It was the largest remnant of an even bigger iceberg that calved off the Larsen C ice shelf in July 2017.
There are no permanent settlements in South Georgia or the nearby Sandwich Islands, but the U.K. maintains two research bases and oversees commercial fishing in the area.
Many icebergs have become caught in the shallow waters around South Georgia, where they linger and slowly melt over long periods of time.
Part of a massive iceberg known as A38 ran aground at South Georgia in 2004, causing mass die-offs among seal pups and penguin chicks. The iceberg had split in two, leaving behind one piece that measured 70 kilometres long and 19 kilometres wide.
— With files from The Associated Press and Global News
© 2025 Global News, a division of Corus Entertainment Inc.
