A23a, the world’s largest iceberg, is moving toward South Georgia Island, threatening large populations of seals, penguins and other wildlife.
The A23a iceberg, twice the size of Greater London, is floating in the ocean. Image: British Antarctic Survey
A23a weighs nearly 1,000 billion tons, is 3,900 km2 wide and about 400 m thick, equivalent to the height of the Empire State Building. It separated from Antarctica’s Filchner-Ronne ice shelf in 1986, quickly became stuck on the seabed in the Weddell Sea, stood still for about 30 years, then began to move slightly a few years ago. Currently, the iceberg is drifting across the Southern Ocean and toward South Georgia Island, IFL Science reported on January 23.
Icebergs can be very dangerous. In 2016, iceberg B09B with an area of 100 square kilometers crashed into Cape Denison in Commonwealth Bay, Antarctica. The ice block has blocked the local penguins’ way to the sea, which means blocking their food source of fish, causing the number of individuals to plummet. One study estimates that 150,000 of the 160,000 penguins in the region may have lost their lives due to this incident.
South Georgia Island is located in the Iceberg Alley, a natural passage in Antarctica that regularly contains icebergs swept in by the Antarctic Circumpolar Current. Therefore, the local ecosystem is accustomed to iceberg collisions and has a certain ability to withstand the impact. “South Georgia is located in the Iceberg Alley so collisions are to be expected with the seafood and wildlife industries, and both are well adapted,” said Mark Belchier, a private marine ecologist. consultant to the South Georgia government, explains.
However, icebergs also caused chaos on this remote island. When iceberg A38 became stranded near South Georgia in 2004, large numbers of baby penguins and seal pups died because their parents’ feeding routes were disrupted.
As the world’s largest iceberg, A23a has the potential to cause more serious damage. However, icebergs are difficult to predict and no one knows for sure what will happen next. Whether A23a avoids South Georgia or gets stuck along the island, the event will provide a rare opportunity for scientists to study the resilience of ecosystems to major environmental change.