World’s Largest Iceberg Breaking Up into Several Large Chunks
LONDON — The massive A23a iceberg, once the world’s largest, is now rapidly breaking up into multiple very large chunks, according to scientists from the British Antarctic Survey (BAS).
Originally weighing close to a trillion metric tonnes (1.1 trillion tons) and covering an area of 3,672 square kilometers (1,418 square miles) — slightly larger than Rhode Island — the A23a iceberg has been closely monitored by scientists since it calved from the Filchner-Ronne ice shelf in Antarctica back in 1986.
A23a has held the title of the “largest current iceberg” multiple times since the 1980s, occasionally being surpassed by larger but shorter-lived icebergs like A68 in 2017 and A76 in 2021.
Andrew Meijers, an oceanographer at BAS, revealed to CNN via email: “The iceberg is rapidly breaking up, and shedding very large chunks, themselves designated large icebergs by the US national ice center that tracks these.”
The “megaberg” has now dwindled to about 1,700 square kilometers (656 square miles), roughly equivalent to the size of Greater London.
A23a remained grounded on the Antarctic’s Weddell Sea floor for over three decades, until it likely shrank enough to break free and float away.
In 2020, it was carried by ocean currents before getting stuck in a Taylor column — a spinning vortex caused by ocean currents hitting an underwater mountain — until it started moving again last December. By March of this year, it had run aground on a continental shelf before breaking loose once more in May.
Meijers explained the events leading to the iceberg’s breakup. “It has been following the strong current jet known as the Southern Antarctic Circumpolar Current Front (SACCF) anti-clockwise around South Georgia ever since it floated loose in May, after grounding on the continental shelf for a few months in March.
He added that A23a is “following a similar fate” to other megabergs like A68 in 2021 and A76 in 2023, which also disintegrated around South Georgia.
The disintegration of A23a means the title of world’s largest iceberg now belongs to D15a, measuring around 3,000 square kilometers (1,158 square miles) and currently stationary near the Australian Davis base in Antarctica.
Although A23a remains the second-largest iceberg globally, Meijers predicts this will change rapidly as it continues to fragment in the upcoming weeks due to warmer water temperatures and the onset of southern spring.
While iceberg calving is a natural process, scientists are uncertain if megabergs are increasing as the planet warms. However, it is evident that ice shelves have lost trillions of tons of ice from increased iceberg formation and melting, largely due to warming ocean waters and shifting currents.
Human-induced climate change is driving concerning alterations in Antarctica, posing a risk of catastrophic sea level rise.
Researchers aboard the BAS polar research vessel RRS Sir David Attenborough visited the A23a while it was grounded on the South Georgia shelf. Samples collected during the visit have been brought back to the UK for analysis, a BAS spokesperson confirmed.
“The grounding and massive release of cold freshwater likely had a significant impact on the seabed organisms and surrounding water,” the spokesperson stated. “Understanding these impacts is crucial as large icebergs may become more common at South Georgia due to global warming.” — CNN
