World's Largest Iceberg Drifts Slowly Towards South Georgia

The world's largest iceberg is slowing heading towards the island of South Georgia, where it may have serious affects on local wildlife. 

Iceberg A23a is so big that it ihard to visualize: at 1.1 million acres in area, it is about 75 times larger than Manhattan (and shrinking). Fornow, it measures about 40 nautical miles by 32 nautical miles on a side, and it weighs about one trillion tonnes. Its sheer sides tower more than 1,300 feet above the water, and chunks regularly break off in the waves. 

The berg's arrival has been a long time coming. A23a broke off of Antarctica's Filchner-Ronne Ice Shelf in 1986, and began to drift off into the Weddell Sea (taking a Soviet research base with it). It ran aground almost immediately, and stayed anchored to the bottom until 2020, when it finally refloated and began to drift to the northwest. It took three years to reach the tip of the Antarctic Peninsula, and finally reached the Antarctic Circumpolar Current in April 2024. This was expected to shuttle the iceberg northeast into the Atlantic, where it would melt in warmer waters.  

However, A23a stalled in the South Orkney Islands for much of 2024. Oceanographers say that it was likely caught in a Taylor Column - a rotating cylindrical current found above a rise on the bottom. It kicked loose from this spinning water trap late last year and drifted away towards South Georgia, which is now about 180 miles away. 

When it finally breaks up, the iceberg will pose a hazard to the area's sparse vessel traffic - primarily fishermen - and may block in the rugged beaches of South Georgia, home to King penguins and seals. The last megaberg that reached the island broke up in 2023, and its remains still make a mess of commercial navigation. Fishing vessels operating near South Georgia have to negotiate a shifting city of giant ice blocks to get to and from their fishing grounds. "It is in bits from the size of several Wembley stadiums down to pieces the size of your desk," Andrew Newman of fishing company Argos Froyanes told BBC.

The ice can also make it harder for penguins and seals to access the water from their breeding grounds on shore. Mark Belchier, director of fisheries and environment for the government of South Georgia, told CNN that any impact on wildlife from beach obstructions would be "highly localized and transient."