The colossal Antarctic iceberg, taller than the Empire State Building, began moving thirty years after its formation

The largest iceberg in the world is finally moving after more than thirty years.

The A23a, as it is known, broke up off the Antarctic coast in 1986 but almost immediately became stuck in the Weddell Sea, virtually turning it into an ice island.

Its area is approximately 4,000 km2. To put its size into context, consider that the nearby South Georgia and South Sandwich Islands have an area of ​​about 3,900 km2 and the island of Great Malvina (or West Falkland) has an area of ​​about 4,500 km2.

Last year it moved at high speed and is now about to leave Antarctic waters.

The A23a is a real giantand impresses not only with its surface.

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This ice sheet has approx 400 meters thick. By comparison, the Shard in London measures only 310 meters, the Empire State Building in New York 380 meters and the Great Santiago Tower in Santiago de Chile 300 meters, to name just a few buildings that stand out for their height.

A23a was part of a massive calving of icebergs from the Filchner Ice Shelf in Antarctica.

It housed a Soviet research station, which shows how long ago the detachment took place.

Moscow sent an expedition to remove the equipment from the Druzhnaya 1 base, fearing that it would be lost. But the iceberg didn’t get far from shore before it became firmly anchored to the bottom of the Weddell Sea.

So, Why is the A23a now moving after almost 40 years?

“I asked a few colleagues about it, to see if there was any change in water temperature that could have caused this, but the consensus is that it was just time,” remote sensing expert Andrew Fleming told him. Survey, to BBC science correspondent Jonathan Amos.

“It had been stranded since 1986, but at some point it would shrink enough (in size) to lose traction and start moving. “I detected the first movement in 2020.”

A23a’s movement has accelerated in recent months, driven by wind and currents, and is now passing the northern tip of the Antarctic Peninsula.

Like most icebergs in the Weddell sector, A23a will likely be pushed into the Antarctic Circumpolar Current, which will in turn launch it into the South Atlantic Ocean on a trajectory known as “iceberg alley”.

This is the same movement of water – and the westerly wind – that famed explorer Ernest Shackleton used to escape Antarctica in 1916 after losing his ship, the Endurance.

Shackleton turned his lifeboat towards South Georgia. Large icebergs are regularly seen around this island. The keels of icebergs tend to get stuck in the shallow continental shelf of the British Overseas Territory.

Finally, All icebergs, no matter how big, are doomed to melt and disappear.

Scientists will closely monitor the evolution of A23a.

If it makes landfall in South Georgia, it could cause problems for the millions of seals, penguins and other seabirds that thrive on the island. The large size of A23a could disrupt the animals’ normal routes, preventing them from properly feeding their young.

But It would be a mistake to think that icebergs are only dangerous objects (the Titanic and so on). Its importance for the environment in general is increasingly recognised.

As they melt, these large icebergs release the mineral dust that was absorbed into their ice when they were part of the Antarctic glaciers. This dust is a source of nutrients for the organisms that form the basis of the ocean’s food chains.

“In many ways these icebergs are life-giving; “They are the origin of a lot of biological activity,” says Catherine Walker of the Woods Hole Oceanographic Institution, who was born the same year as A23a.

‘I identify with him; “He has always been there for me.” (JO)