Fears grow as world’s largest iceberg drifts towards South Georgia

A23a poses risks to wildlife, vessels in the south Atlantic region.

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The world’s largest iceberg, A23a, is drifting northward from Antarctica, potentially threatening South Georgia, a British Overseas Territory in the South Atlantic.

The massive iceberg, spanning 3,672 square kilometres (1,418 square miles), has raised fears of ecological disruption and risks to shipping routes.

Scientists warn that if A23a becomes grounded on South Georgia's continental shelf, it could block access to critical feeding grounds for seals and penguins, which depend on the island's rich marine resources for survival.

A satellite image of A23a in Antarctica taken in November 2023. European Union/Copernicus Sentinel-3/Handout/Reuters

“If this happens, it could seriously impede access to feeding grounds for the wildlife – seals and penguins mostly – that breed on the island,” said Andrew Meijers, an oceanographer at the British Antarctic Survey.

The iceberg, slightly smaller than Rhode Island and more than twice the size of London, was calved from Antarctica’s Filchner-Ronne ice shelf in 1986. For over 30 years, it remained grounded on the Weddell Sea floor until it shrank just enough to break free.

It then drifted with ocean currents and became stuck again in a Taylor column—a spinning vortex of water caused by underwater mountains.

In December 2024, the iceberg finally broke free and began moving towards warmer waters. While scientists initially expected it to break into smaller fragments, recent satellite images show it has retained its structure.

The largest iceberg in the world, A23a, could be headed for the British overseas territory of South Georgia. Jean-Felix Fayolle/Zeppel/SIPA/Shutterstock

Simon Wallace, a sea captain from the South Georgia government vessel Pharos, described the iceberg as a significant threat to shipping routes. “Icebergs are inherently dangerous. The larger ones are easier to track and avoid, but smaller fragments are harder to detect and can be equally hazardous,” he told CNN.

Wallace warned that fragmented pieces could fill South Georgia’s bays and fjords, creating navigational challenges for vessels.

Mark Belchier, director of fisheries and environment for South Georgia and the South Sandwich Islands, also expressed concern over the potential impact on shipping and fishing activities in the region.

“Whilst they are common at South Georgia, they can cause issues for shipping and fishing vessels,” Belchier said.

Scientists believe the iceberg’s detachment from the ice shelf was part of its natural growth cycle and not directly caused by climate change. However, global warming is driving significant changes in Antarctica, accelerating ice loss and contributing to rising sea levels.

South Georgia, a biodiversity hotspot, is home to one of the world’s largest Marine Protected Areas. While any impacts of the iceberg are expected to be localised and temporary, the situation highlights the delicate balance of the region's ecosystem.

Experts are closely monitoring the iceberg’s trajectory to determine whether it will drift into the open South Atlantic or become lodged on the continental shelf near South Georgia.

The British Antarctic Survey is using satellite imagery and ocean current models to predict its movements in the coming weeks.

The movement of A23a underscores the growing challenges posed by Antarctic icebergs to ecosystems, marine industries, and global climate stability.

As the world grapples with the effects of climate change, events like this serve as a stark reminder of the interconnectedness of natural and human systems.