The world’s biggest iceberg is on the loose and is threatening to collide with a tiny south Atlantic island, potentially affecting the wildlife there, scientists warned this week.
Known as A23a, the 1,400-square-mile iceberg had been stuck on the ocean floor near Antarctica for 37 years, after splitting in 1986 from the Antarctic’s Filchner Ice Shelf.
But it began to move again last year and is now approaching South Georgia Island, a small island mainly populated by penguins and seals.
The iceberg had been stuck in a rotating water column near the South Orkney Islands since April 2024, according to Andrew Meijers of the British Antarctic Survey. “It has now come loose from this circulation feature and is heading northeast with the Antarctic circumpolar current – on a path that is likely to bring it very close or in contact with the island of South Georgia,” he said.
“Sudden isn’t really the right word for something we’ve been tracking for almost 40 years and is now moving at around half a mile an hour,” Meijers told USA TODAY in an e-mail Tuesday. “However, its recent path shows that it is in an ocean current jet – something like an atmospheric jet stream – that should take it toward the island over the coming weeks. ”
The iceberg might hit the island in about 2-4 weeks, depending on the meandering of the current and its exact path, according to Meijers, It may follow the current around the continental shelf of the island and not ground at all – as a recent large berg has done − or it may potentially ground on the shallow waters of the continental shelf, as a berg did in 2004.
“It is almost impossible to predict which of these may occur, or indeed if the berg will break up before then,” he said.
Icebergs are a regular threat to the British territory of South Georgia Island because it’s near the Southern Hemisphere’s version of “Iceberg Alley.” (Not to be confused with the Northern Hemisphere’s Iceberg Alley, which is located near Labrador and Newfoundland in Canada.)
Antarctica is ringed by a powerful counterclockwise current, according to the National Science Foundation. “Many icebergs float in this current around the continent until they get close to the Antarctic Peninsula, a long arm that extends toward Chile.
“In the Scotia Sea between Chile and Antarctica, the icebergs are pushed northward and begin to melt. Researchers call this area Iceberg Alley,” the NSF said.
South Georgian populations of seals and penguins may be impacted if the iceberg grounds near the island, Meijers said. “This could potentially interrupt their pathway to feeding sites and force them to expend more energy for adults to travel around it. This will reduce the amount of food coming back to pups and chicks on the island, and so increase mortality.
“This has happened before in 2004, although we aren’t certain if this berg will ground or not, more recent examples have tracked around the island.”
As for impacts on humans, “while the berg is large it is easily avoided by Southern Ocean shipping operators, who are well aware of the dangers bergs pose − and the location of A23a,” he said. “However, as it breaks up over time the smaller bergs are much harder to track. Discussions with fishing operators suggests that past large bergs have made some regions more or less off-limits for fishing operations for some time due to the number of smaller – yet often more dangerous – bergy bits.”