How big is A23a? World’s largest iceberg on the move after 37 years

The largest iceberg in the world, A23a, has moved after almost four decades. Scientists declared on Friday, November 24, that it is moving for the first time in decades and is headed toward the Southern Ocean.

Oliver Marsh, a glaciologist with the British Antarctic Survey, told Reuters that it's uncommon to witness an iceberg this size moving. He also said,

“Over time it’s probably just thinned slightly and got that little bit of extra buoyancy that’s allowed it to lift off the ocean floor and get pushed by ocean currents."

The BBC said on Friday that the iceberg, known as A23a, is floating and expected to depart the Weddell Sea, where it has been stranded since the 1980s.

With a surface area of roughly 4,000 square kilometers, or 1,500 square miles, it is the largest iceberg in the world. As a result, it is approximately three times larger than New York City and more than twice the size of Greater London.

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A23a finally floats away after getting stuck on the ocean floor for years

A23a is thrice the size of NYC (Image via British Antarctic Survey / NASA)

Scientists are keeping a careful eye on A23a as it moves north. It was formerly a portion of the Filchner ice shelf in West Antarctica and hosted numerous research stations during the 20th century, including Druzhnaya 1 in the Soviet Union. When the Filchner-Ronne Ice Shelf broke apart in 1986, it was left adrift and permanently altered the continent's coastline.

From then on, it had stayed anchored to the Weddell Sea floor. However, by August 2022, the iceberg's tether had melted, and based on satellite images, A23a began its current journey across the Weddell Sea.

The nearly trillion-ton chunk is presently making its way swiftly across the South Atlantic's perilous waters and past the Larsen ice shelf. Like many icebergs before it, this city-sized chunk of ice will probably slowly melt into the surrounding waters as it drifts toward South Georgia Island.

Regarding the same, British Antarctic Survey expert in remote sensing Andrew Fleming told the BBC that,

"It was grounded since 1986 but eventually it was going to decrease sufficiently to lose grip and start moving".

The iceberg will probably be thrown into the Antarctic Circumpolar Current. This will direct it along the "iceberg alley," a route that leads to the Southern Ocean, where similar icebergs can be seen floating in the icy waters.

However, scientists fear that A23a may ground near South Georgia Island in the southern Atlantic, which might have catastrophic effects on wildlife in the Antarctic. The animals' only food supply, the ocean, might be cut off if that takes place.

On the brighter side, scientists now understand that the iceberg can carry minerals scraped from the ocean floor. According to the BBC, these may get scattered when the iceberg melts, contributing nutrients to the local animal life.

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The A76 iceberg, which had broken off from the Ronne Ice Shelf in the Weddell Sea, momentarily overtook the iceberg as the biggest in the world in May 2021. However, according to the Guinness World Records website, A23a reclaimed the world's No. 1 position in October 2022 after the previous record-holder, A76, fractured into three pieces.