An iceberg twice the size of London is on the move and putting a remote natural paradise at risk

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One of the world’s largest icebergs is drifting beyond Antarctic waters after being grounded for more than three decades, according to the British Antarctic Survey.

The iceberg, known as A23a, split from the Antarctic's Filchner Ice Shelf in 1986. But it became stuck to the ocean floor and remained for many years in the Weddell Sea.

Now, it’s on the move thanks to strong currents and winds, and its trajectory may spell disaster for a remote wildlife-rich island.

The iceberg is about three times the size of New York City and more than twice the size of Greater London, measuring around 4,000 square kilometers.

World’s largest iceberg is on the move

Andrew Fleming, a remote sensing expert from the British Antarctic Survey, told the BBC on Friday that the iceberg has been drifting for the past year and now appears to be picking up speed.

A23a, which is also one of the oldest icebergs in the world, is moving past the northern tip of the Antarctic Peninsula, helped by wind and ocean currents.

“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,” Fleming told the BBC.

“It was grounded since 1986, but eventually it was going to decrease (in size) sufficiently to lose grip and start moving," he added.

Fleming said he first spotted movement from the iceberg, which weighs almost a trillion metric tonnes, in 2020.

The British Antarctic Survey said it has now ungrounded and is moving along ocean currents to sub-Antarctic South Georgia.

The frozen behemoth will likely be channelled towards the Southern Ocean along a path dubbed ‘iceberg alley,’ where other giant bergs are floating.

Is the iceberg dangerous?

There is a chance that the A23a iceberg could become grounded again at South Georgia island, which would pose a threat to one of the world’s most important ecosystems.

The remote island is home to millions of macaroni, gentoo and king penguins as well as seals, albatross and other rare wildlife. Of the 30 species of birds that breed there, 11 are considered to be threatened or near threatened by the International Union for Conservation of Nature (IUCN).

With no permanent human inhabitants, the island has levels of biodiversity comparable to the Galapagos Islands.

To protect this precious ecosystem, the Government of South Georgia & the South Sandwich Islands created one of the world’s largest Marine Protected Areas in the region in 2012.

The colossal A23a iceberg threatens catastrophe for this wildlife haven as it could prevent animals like seals, penguins and seabirds from feeding in the surrounding waters.

In 2020, similar concerns were raised after another massive iceberg, A68, started heading towards the island. Disaster was avoided, however, as the iceberg split into smaller pieces, which could be the fate of A23a as well.