World’s biggest iceberg A23a appears to have run aground near South Georgia

Iceberg A23a near South Georgia

The world’s biggest iceberg appears to have run aground around 70 kilometres from a remote Antarctic island, a research organisation said on Tuesday, potentially saving the vital wildlife haven from a collision.

The enormous iceberg A23a, which weighs almost one trillion tonnes and is more than twice the size of Greater London, has been drifting north from Antarctica towards South Georgia island since 2020.

Its journey had prompted fears that it might strike the island or become grounded in nearby shallow waters, potentially making it harder for penguins and seals to feed their young.

But the vast wall of ice has been stationary 73 kilometres from the island since 1 March, the British Antarctic Survey (BAS) said in a statement.

"If the iceberg stays grounded, we don't expect it to significantly affect the local wildlife," said BAS oceanographer Andrew Meijers.

"In the last few decades, the many icebergs that end up taking this route through the Southern Ocean soon break up, disperse and melt," added Meijers, who encountered A23a in late 2023 and has followed its progress by satellite since then.

Satellite images examined by AFP showed that the nearest edge of the approximately 3,300-square-kilometre iceberg had come to a stop more than 70 kilometres from the island in late February.

Whether the iceberg is permanently stuck remains uncertain.

"It will be interesting to see what will happen now," Meijers added.

Could A23a benefit South Georgia’s wildlife?

The world’s biggest and oldest iceberg calved from the Antarctic shelf in 1986.

It stayed grounded for more than 30 years before eventually breaking free in 2020. At times during its slow northward journey, ocean forces held it spinning in one place.

Earlier satellite images had indicated that it was not breaking into smaller pieces along the familiar route followed by such icebergs. In January, however, a 19-kilometre chunk broke away.

There had been worries about wildlife on South Georgia, an important breeding ground, if the iceberg settled too close to the island.

Animals such as penguins and seals would have had to travel much further to get around the immense block of ice.

"This could reduce the amount of food coming back to pups and chicks on the island, and so increase mortality," Meijers explained.

In its present position, however, the iceberg could have benefits for wildlife.

"Nutrients stirred up by the grounding (of the berg) and from its melt may boost food availability for the whole regional ecosystem, including for charismatic penguins and seals," Meijers said.

South Georgia and the nearby South Sandwich Islands are home to approximately five million seals and 65 million breeding birds from 30 species.

Meijers told AFP in January that the island’s seals and penguins had already experienced a "bad season" because of a bird flu outbreak.

Shipping and South Georgia

The iceberg presents no danger to shipping: it is large enough for vessels to avoid it easily.

As it breaks into smaller fragments, though, some areas could become inaccessible to commercial fishing vessels "due to the number of smaller – yet often more dangerous – bergy bits", Meijers said.

South Georgia has no permanent human population and is administered by the UK as a British overseas territory.

Argentina also claims the island, as well as the Falklands to the west, which it calls Las Malvinas.

What about climate change?

Icebergs this large are uncommon but not unprecedented, Meijers said, with two of similar size appearing in the same area over the past five years.

Meijers stressed that enormous icebergs are a "completely normal part of the lifecycle" of Antarctic ice sheets.

But he added that ice shelves have lost 6,000 billion tonnes of mass since 2000, alongside accelerating ice loss attributed to climate change.

Last month, researchers warned that an increase in the planet’s average temperature to between 1.5 and 2.0 degrees Celsius above pre-industrial levels could melt enough frozen water to raise oceans by a dozen metres, and beyond the point of no return.

Last year was the first calendar year above 1.5 °C. It shattered previous heat records as fires, floods and storms battered the world.

© Agence France-Presse