‘Queen of icebergs’ A23a grounds off South Atlantic wildlife haven

After months on the move, the world’s largest iceberg, A23a, has run aground off the remote British island of South Georgia, representatives from the British Antarctic Survey (BAS) reported on Tuesday (Mar. 4).

The megaberg, which is roughly the size of Rhode Island, struck shallow waters 50 miles (80 kilometers) from the South Atlantic wildlife haven, the BBC reports, and researchers are keenly observing what it will do next.

“In the last few decades, the many icebergs that end up taking this route through the Southern Ocean soon break up, disperse and melt,” Andrew Meijers, an oceanographer at the BAS, said in a statement. “It will be interesting to see what will happen now.”

A23a, nicknamed the “queen of icebergs,” first broke off from Antarctica’s Filchner Ice Shelf in 1986. However, it remained tethered to the seabed for more than three decades before it finally began to break free in 2020, according to the BAS.

In 2024, the icy colossus then got stuck again, spinning in one spot for several months just north of the South Orkney Island. But in December 2024 it broke free once more and continued its journey northwards.

When A23a’s trajectory towards South Georgia first became apparent in January, experts feared a collision could be catastrophic for the large colonies of penguins, seals and other marine wildlife that live there.

Related: 45-mile-long iceberg slams into penguin refuge in Antarctica, almost causing ecological disaster

If the megaberg stays grounded, Meijers said it is unlikely to pose a significant threat to the local wildlife. But if it moves closer to the island or breaks apart, “it could interrupt their pathway to feeding sites and force the adults to expend more energy to travel around it,” he said. “This could reduce the amount of food coming back to pups and chicks on the island, and so increase mortality.”

Similar fears were raised in 2020, when the previous world’s largest iceberg, A68a, came perilously close to grounding right next to South Georgia before it was eventually ripped apart into many smaller pieces by ocean currents.

However, there could also be an upside to the recent iceberg grounding: “If the berg is stimulating ocean productivity, this could actually boost populations of local predators like seals and penguins,” Meijers said.

As well as stirring up nutrients from the ocean floor, megabergs also contain a vast amount of nutrients locked away in their ice. “It’s like dropping a nutrient bomb into the middle of an empty desert,” Nadine Johnston, a marine ecologist at the British Antarctic Survey, told BBC.

However, Meijers added that, as the berg disintegrates, it might pose a threat to local sailors and fishermen. “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.”

BAS will continue to monitor the effects of this iceberg on the surrounding ecosystem.