World's largest iceberg A23a resumes journey after being stuck for months

The colossal iceberg A23a, the world’s largest and oldest, has resumed its movement northward after being immobilized for months near the South Orkney Islands.

Measuring twice the size of Greater London and weighing around one trillion tonnes, A23a remained grounded in the Weddell Sea for over 30 years before it began drifting in 2020. Recent changes indicate it is now being propelled by the Antarctic Circumpolar Current, potentially steering it toward South Georgia.

A23a’s stagnation was caused by a Taylor Column, an oceanographic phenomenon where rotating water over an underwater seamount temporarily halts the movement of objects. Dr. Andrew Meijers, an oceanographer at the British Antarctic Survey (BAS), explained the significance of the iceberg's movement, noting that scientists are eager to study its path and its ecological impact. He added that tracking A23a’s journey can reveal whether it will follow routes similar to other massive Antarctic icebergs.

Researchers aboard the British Antarctic Survey’s RRS Sir David Attenborough have been closely monitoring A23a as part of the BIOPOLE project, which examines its influence on the surrounding ecosystem. Laura Taylor, a biogeochemist working on the project, noted that large icebergs like A23a often enhance marine biodiversity by distributing nutrients as they drift. These nutrient-rich waters can foster life in otherwise barren regions, playing a vital role in oceanic carbon cycles.

Scientists believe that as A23a nears the warmer waters around South Georgia, it will likely begin to fracture into smaller pieces and eventually melt. This process will offer researchers valuable insights into the iceberg’s environmental role, particularly its effects on marine ecosystems and nutrient dynamics.