The Largest Iceberg In The World Has Become Trapped In An Ocean Vortex, Slowly Spinning In Circles Near The South Orkney Islands
Since 2020, the largest iceberg in the world has been drifting north from Antarctica toward warmer waters.
But now, according to the British Antarctic Survey (BAS), its course has been interrupted after becoming trapped in an ocean vortex.
The iceberg, named A23a, is slowly spinning around and around in a rotating cylinder of water called a Taylor column. It is near the South Orkney Islands, which is located approximately 375 miles northeast of the Antarctic Peninsula. Each day, the iceberg rotates about 15 degrees.
“It’s basically just sitting there, spinning around, and it will very slowly melt as long as it stays there,” said Alex Brearley, an oceanographer at the British Antarctic Survey. “What we don’t know is how quickly it will actually come out of this.”
The iceberg could continue spinning for a year or maybe even two. Experts just aren’t quite sure. Previously, A23a was part of Antarctica.
Now, it is an iceberg the size of Rhode Island. In 1986, it split off from the Filchner-Ronne Ice Shelf on the continent’s northwestern side, taking the Soviet research station Druzhnaya 1 with it. In February 1987, the Soviets traveled to the iceberg to retrieve their equipment.
After that, the iceberg stayed fixed in place for 34 years in the Weddell Sea off the coast of West Antarctica. However, it started to move in 2020. This past November, A23a floated out into the Southern Ocean, moving at a rate of three miles per day.
According to BAS glaciologist Olivia Marsh, A23a had gotten thin enough to lift off from the ocean floor and be carried away by ocean currents.
The iceberg was predicted to take a path known as “iceberg alley” to reach the island of South Georgia in the Atlantic Ocean, propelled forward by the Antarctic Circumpolar Current.
Gabrielle – stock.adobe.com – illustrative purposes only
But A23a has not yet made it to that destination. Right now, it is spinning in the South Orkney Islands, which is over 500 miles southwest of South Georgia.
A rotating cylinder of water large enough to trap an iceberg is created when the physical features of the ocean floor block the flow of a current.
“You can make these Taylor columns quite easily in a rotating tank experiment in your lab. But to see it on a geophysical scale like this is really rare,” said Till Wagner, who studies ocean ice at the University of Wisconsin-Madison.
In December, scientists gathered samples of seawater from around the iceberg to determine how the iceberg can impact the atmosphere and the carbon in the ocean. They can also help reveal what kind of life could form around A23a.
The iceberg followed a route similar to the one that the iceberg A68a took. It also spent several months spinning.
Usually, icebergs headed east to warmer waters start to melt. Since A23a is now stuck for who knows how long, it has managed to delay its melting, which is good news.
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