The largest and oldest iceberg in the world, A23a, is on the move again, after being stranded on the seabed for decades and, more recently, starting to rotate. According to information from the British Antarctic Survey (BAS), the mega-iceberg broke free from its position north of the South Orkney Islands and is now adrift in the Southern Ocean.
Also according to the British Institute for Polar Research, the colossus A23a is 3,800 square kilometers, which is more than twice the size of Greater London, and is 400 meters thick, says the BBC.
The iceberg calved from Antarctica’s Filchner Ice Shelf in 1986 and remained stranded on the seabed in the Weddell Sea for more than 30 years before beginning its slow journey north in 2020.
According to the researchers, the iceberg’s journey was marked by intriguing scientific events. For months, the iceberg was trapped in a Taylor column, an oceanographic phenomenon in which the rotation of water above a seamount locks objects in place. This dynamic kept A23a spinning at one point, delaying its expected rapid northward drift.
A23a is forecast to continue its journey to the Southern Ocean following the Antarctic Circumpolar Current, which will likely take it towards the sub-Antarctic island of South Georgia. In this region, it will encounter warmer waters and is expected to break up into smaller icebergs and eventually melt.
For Andrew Meijers, oceanographer at BAS, who co-leads the OCEAN: ICE project, which aims to understand how the ice sheet affects the ocean, it is “exciting to see A23a moving again after periods of standstill”.
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We are interested to see if it will follow the same path as the other large icebergs that have calved from Antarctica. And, most importantly, the impact this will have on the local ecosystem.
