Transport near Antarctica is becoming a little more difficult as A23a, the world’s oldest and largest iceberg, has broken a water trap north of the South Orkney Islands and is drifting north on the Antarctic Circumpolar Current. .
The trouble with icebergs is that even though they are spectacular behemoths and have had a significant impact on human events (just ask the Titanic), despite their size, they are rather It means it’s fleeting. Once they break away from the glaciers from which they were born, they drift north or south, as the case may be, to warmer latitudes, where they quickly break apart and melt away like memories.
For this reason, signifiers like the world’s largest or oldest are temporary at best. A23a is not the largest ever recorded. That title goes to B-15, which broke away from Antarctica’s Ross Ice Shelf in March 2000. Nor is it the largest recent glacier, like A-68, which broke away from the Larsen Ice Shelf in 2017. But it is the oldest one. And the biggest iceberg at the moment.
A23a
This doesn’t turn it into ice. When last measured, its area was 1,500 miles 2 (3,900 km 2), or twice the size of Greater London, and it weighed an estimated 1 trillion tons, or the equivalent of 250 billion African elephants.
It is also the oldest known iceberg, as it was born in 1986 from the Filchner Ice Shelf in Antarctica.It then ran aground on the ocean floor and was kept in cold storage until it washed ashore in the Weddell Sea in 2020.
Then things got a little weird. Around April 2024, we encountered an oceanic phenomenon called the Taylor Column. Simply put, this is a giant vortex caused by a rotating column of water that forms above a mountain on the ocean floor. A23a was trapped in this maelstrom for months, floating in an unstable circle, until recent satellite images show it finally freed and headed for the sub-Antarctic island of South Georgia, located at about 54 degrees south latitude. It was confirmed that the ship was drifting north.
A23a satellite image
Tracking A63a is of more than scientific interest. Such huge mountains melt and release mineral nutrients along with large amounts of fresh water. In the open sea, this can be very beneficial, but if one of these were to run aground, as was threatened in South Georgia, it would tear up the ocean floor and allow more fresh water to enter the local ecosystem. There is a possibility of flooding.
“We know that these giant icebergs can provide nutrients to the bodies of water they pass through and create thriving ecosystems in otherwise unproductive areas,” he says. said biogeochemist Laura Taylor, a member of the British Antarctic Survey’s 2023 BIOPOLE cruise. “What we don’t know is what difference a particular iceberg, its size and origin will make to the process.
“We took samples of sea surface water behind, immediately next to, and in front of the iceberg’s route. They give us an idea of what kind of life might form around A23a and if it This will help us determine how this will affect the balance between ocean carbon and the atmosphere.”
Source: British Antarctic Survey
