World’s Biggest Iceberg on the Move After 30 Years

The world’s biggest iceberg is on the move after more than 30 years being stuck to the ocean floor. From a report: The iceberg, called A23a, split from the Antarctic coastline in 1986. But it swiftly grounded in the Weddell Sea, becoming, 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. 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. 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.

So, why, after almost 40 years, is A23a on the move now?

“I asked a couple of colleagues about this, wondering if there was any possible change in shelf water temperatures that might have provoked it, but the consensus is the time had just come,” said Dr Andrew Fleming, a remote sensing expert from the British Antarctic Survey. “It was grounded since 1986 but eventually it was going to decrease (in size) sufficiently to lose grip and start moving. I spotted first movement back in 2020.” A23a has put on a spurt in recent months, driven by winds and currents, and is now passing the northern tip of the Antarctic Peninsula.