The world’s largest iceberg, A23a, has run aground off the coast of South Georgia, a British Overseas Territory in the South Atlantic. The iceberg weighs nearly one trillion metric tonnes and spans an area of 3,672 square kilometers (1,418 square miles), making it slightly smaller than Rhode Island and over twice the size of Greater London. It calved from Antarctica’s Filchner Ice Shelf in 1986 and remained grounded in the Weddell Sea for over 30 years before starting to drift in 2020.
A23a’s journey northward has been marked by unusual events, including being trapped in a rotating water column (Taylor Column) for months in late 2024. It eventually broke free and moved toward South Georgia, where it is now grounded approximately 90 kilometers (56 miles) from the island’s shore on the continental shelf.
While initial concerns arose about the iceberg disrupting access to feeding grounds for seals and penguins on South Georgia, scientists now believe its grounding will have minimal negative effects on local wildlife. In fact, nutrients released from its melting could benefit the regional ecosystem by boosting food availability for marine species. However, as the iceberg breaks apart, smaller icebergs could pose hazards to fishing and shipping operations.
Experts suggest that A23a’s calving was part of a natural ice shelf cycle rather than a direct result of climate change. Nonetheless, global warming continues to drive significant changes in Antarctica with potential implications for sea level rise