World's largest iceberg, twice the size of London, grounds near South Georgia Island

The world’s largest iceberg, A23a, appears to have run aground about 70km from South Georgia Island, potentially sparing the wildlife haven from a collision.

The massive iceberg, measuring around 3,300 sq km (more than twice the size of London, which measures around 1,572 sq km), and weighing nearly 1 trillion tonnes, has been drifting north from Antarctica since 2020, raising concerns about its impact on local wildlife, especially penguins and seals.

Andrew Meijers, an oceanographer with the British Antarctic Survey (BAS), stated, “It will be interesting to see what will happen now,” as it remains unclear if the iceberg is permanently grounded. The BAS confirmed that the iceberg has been stuck 73km from the island since March 1.

If it remains grounded, Meijers said, “we don’t expect it to significantly affect the local wildlife.” He also noted that icebergs in this region typically break up and melt over time, though a 19km-long piece of A23a did break off in January.

The iceberg’s proximity to South Georgia had raised fears that it could block access to feeding grounds for penguins and seals, potentially increasing mortality rates among their young.

However, Meijers suggested that the iceberg’s current location might benefit wildlife, as “nutrients stirred up by the grounding [of the iceberg] and from its melt may boost food availability for the whole regional ecosystem.”

South Georgia Island, home to around 5 million seals and 65 million breeding birds, including 30 penguin species, has faced challenges this season due to a bird flu outbreak, further complicating the situation for local wildlife.

Meijers explained that a closer encounter with the iceberg could force animals to travel farther for food, thus reducing the amount of nutrition available for their young.

While the iceberg poses no threat to shipping due to its massive size, the smaller chunks that break off may pose hazards for commercial fishing vessels. As the iceberg breaks apart, certain areas could be off-limits to ships because of the smaller, more dangerous fragments.

Although A23a is the world’s largest and oldest iceberg, it is not unique, with similar icebergs observed in the region in recent years. Meijers explained that icebergs of this size are a "completely normal part of the lifecycle" of Antarctic ice sheets.

However, he warned that ice loss from Antarctica has accelerated, with the ice shelves losing 6,000bn tonnes of mass since 2000, driven by climate change.

Researchers have cautioned that if global temperatures rise between 1.5 and 2.0 degrees Celsius above preindustrial levels, it could result in sea level rise by up to 12 meters, pushing the planet past the point of no return.