The world’s biggest iceberg is on the move after more than 30 years being stuck to the ocean floor.
A23a, as it’s called, calved from the Antarctic coastline in 1986, but almost immediately grounded in the Weddell Sea to become, essentially, an ice island.
At almost 4,000 sq km (1,500 sq miles) in area, it’s more than twice the size of Greater London.
The past year has seen it drifting at speed, and the berg is now about to spill beyond Antarctic waters
Great icebergs, such as the recent A68 object, “fertilise” the oceans with mineral nutrients
A23a is a true colossus, and it’s not just its width that impresses.
This slab of ice is some 400m (1,312 ft) thick. For comparison, the London Shard, the tallest skyscraper in Europe, is a mere 310m tall.
A23a was part of a mass outbreak of bergs from the White Continent’s Filchner Ice Shelf.
At the time, it was hosting a Soviet research station, which just illustrates how long ago its calving occurred.
Moscow despatched an expedition to remove equipment from the Druzhnaya 1 base, fearing it would be lost. But the tabular berg didn’t move far from the coast before its deep keel anchored it rigidly to the Weddell’s bottom-muds.
Iceberg A23a first began to stir from its long static slumber in 2020
Like most icebergs from the Weddell sector, A23a will almost certainly be ejected into the Antarctic Circumpolar Current, which will throw it towards the South Atlantic on a path that has become known as “iceberg alley”.
This is the same movement of water – and accompanying westerlies – that the famous explorer Sir Ernest Shackleton exploited in 1916 to make his escape from Antarctica
following the loss of his ship, the Endurance, in crushing sea-ice.
Scientists will be following A23a’s progress closely.
If it does ground at South Georgia, it might cause problems for the millions of seals, penguins and other seabirds that breed on the island. A23a’s great bulk could disrupt the animals’ normal foraging routes, preventing them from feeding their young properly.
