After spending decades stranded on the seabed, mega iceberg A23a has broken free from its position north of the South Orkney Islands and is now drifting in the Southern Ocean.
The colossus A23a, which with 3,000 square kilometers Double the size of Greater London and weighing almost a trillion tonnes, it broke off from Antarctica’s Filchner Ice Shelf in 1986 and remained stranded on the seabed of the Weddell Sea for more than 30 years before beginning its slow journey toward the north in 2020.
The iceberg’s journey has been marked by intriguing scientific events. For months, the iceberg was trapped in a Taylor plume, an oceanographic phenomenon in which rotating water on a seamount traps objects in place. This dynamic kept A23a spinning in one place, delaying its expected rapid northward drift.
A23a is expected to continue its journey towards the Southern Ocean following the Antarctic Circumpolar Current, which probably drives it towards the subantarctic island of South Georgia. In that region you will find warmer water and it is expected to break up into smaller icebergs and eventually melt.
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He Dr. Andrew Meijersan oceanographer at the British Antarctic Survey (BAS), said in a statement: “It is exciting to see A23a moving again after periods of stagnation. We are interested to see if it will take the same route taken by other large icebergs that have calved off Antarctica. “And more importantly, what impact will this have on the local ecosystem.”
Exactly one year ago, researchers aboard the RRS ship Sir David Attenboroughobserved and studied the iceberg while on a scientific mission in the Weddell Sea for the BIOPOLE project. Scientists took the first photographs of the moving iceberg while observing how Antarctic ecosystems and sea ice influence global ocean carbon and nutrient cycles, and collected data alongside the vast iceberg.
Laura Taylorbiogeochemist of the BIOPOLE cruise ship, highlighted the importance of their close encounter with A23a: “We know that these giant icebergs can provide nutrients to the waters they pass through, creating thriving ecosystems in otherwise less productive areas. What we don’t know “is what difference certain icebergs, their scale and their origins can make in that process.”
“We sampled ocean surface waters behind, immediately adjacent to, and ahead of the iceberg’s path. They should help us determine what life could form around A23a and how it affects carbon in the ocean and its balance with the atmosphere,” explains biogeochemistry.
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