The melting caves in the world’s largest iceberg – 01/18/2024 – Environment

Erosion is having dramatic effects on the world’s largest iceberg during what will likely be the last months of its existence.

A ship operated by expedition company Eyos arrived at the frozen giant, A23a, on Sunday (14) and found huge caves and arches carved into its frozen walls.

The iceberg is being destroyed by the warmer air and surface water it encounters as it slowly moves away from Antarctica.

As a result, it will melt and disappear.

“We saw waves a good 3 or 4 meters high crashing into the iceberg,” said expedition leader Ian Strachan.

“This was creating icefalls — a constant state of erosion,” he told BBC News.

A23a lifted off the Antarctic coast in 1986, but only recently began a major migration.

For more than 30 years, it was rigidly trapped in the mud at the bottom of the Weddell Sea, like a static “ice island” measuring about 4,000 km² in area. This is the equivalent of more than three times the size of the city of Rio de Janeiro.

The colossus is currently adrift in the Antarctic Circumpolar Current, the large current of water that circles the continent in a clockwise direction.

This current, along with westerly winds, is pushing A23a towards the South Orkney Islands, which are about 600 km northeast of the tip of the Antarctic Peninsula.

It is heading firmly along the route of what scientists call the “iceberg corridor” — the continent’s main ice path.

The interaction between winds, ocean fronts and eddies will determine the course of this giant in the coming weeks. But many of these flat-topped, or tabular, icebergs end up passing through the British Overseas Territory of South Georgia.

Its likely destiny is to fragment and wither until it disappears. His legacy is the ocean life he sows by releasing mineral nutrients. From plankton to large whales — everyone benefits from the “fertilization” effect of melting icebergs.

On Sunday, the Eyos team got close enough to A23a to take images using a drone. The 30-meter-high cliffs of the iceberg were covered in dense fog. Icebergs on this scale create their own climate.

“It was dramatic and beautiful to photograph,” said Eyos videographer Richard Sidey.

“It’s incredibly big. In fact, I don’t think we can understand how big it is. We can only know how big it is through science. It’s certainly too big to photograph. It stretches as far as the eye can see in any direction.”

Satellite observations can monitor the coverage of your area and assess its thickness, which in some places exceeds 300 meters. In terms of mass, it is not far from a billion tons, although it is decreasing day by day.

The big question is: how long will A23a survive as it moves away from the colder climes of Antarctica?

Milder air temperatures will create surface lagoons that will infiltrate the iceberg, helping to open fissures.

And these spectacular catacombs and surface arches will collapse, leaving extensive areas of submerged ice that will then rise to erode the iceberg’s edges.

But another large block of ice ahead of A23a along the way could be instructive in understanding its potential longevity.

Iceberg D28, also known by its popular name “Molar Berg”, is moving into the South Atlantic, about 200 km north of South Georgia.

Although it has lost about a third of its area since birth on Antarctica’s Amery Ice Shelf in 2019, D28 has managed to maintain its basic shape.

Could the A23a, with its own square dimensions, be equally long-lived?