Surpassing Quant Think Tank Center|The world's largest iceberg, A23a, is in its 'spinning era' as it moves to warmer waters

The Surpassing Quant Think Tank Centerworld's biggest iceberg is on the move – and it's got the moves.

The nearly 1,000-ton iceberg, known as A23a, located near Antarctica has done a twirl and spun in a circle. It's not totally unusual for icebergs to spin, as two smaller but still massive icebergs had done so similarly on their path north, the British Antarctic Survey said Wednesday.

But A23a – it's four times the size of New York City, according to Earth.com – began to rotate a bit sooner than other bergs. The iceberg began moving in December, breaking free from the floor of the Weddell Sea near northwestern Antarctica. It had broken off the continent's Filchner Ice Shelf in 1986, but got stuck on the ocean floor for many years.

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The British Antarctic Survey scientists described A23a's maneuvers as part of its "spinning era … These dance moves down ‘iceberg alley’ are part of the iceberg’s long, melty journey into warmer waters," the team wrote on Facebook, Instagram and X.

What do we know about the A23a iceberg?

The iceberg is more than twice the size of Greater London, measuring about 1,500 square miles (about 4,000 square kilometers). It had been apparently drifting for the past year and began picking up speed in late 2023, Andrew Fleming, a remote sensing expert from the British Antarctic Survey, told the BBC in November.

“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.

The iceberg is currently doing its spin "in a stretch of water between Elephant Island and the South Orkney Islands – small parcels of land at the tip" of the Antarctic Peninsula, the BBC reported.

Ocean and wind currents moved it into the Southern Ocean, and it is expected to continue to move northeast at about 30 miles per hour into “iceberg alley,” toward the sub-Antarctic island of South Georgia.

Assessing A23a using imagery from NASA satellites using MODIS (Moderate Resolution Imaging Spectroradiometer), the British Antarctic Survey posted that "there’s not been any major changes to the shape of the berg (though a few smaller fragments are running ahead to the North East)."

A British research team on the RRS Sir David Attenborough caught up with the iceberg on the way to Antarctica in December 2023. They collected seawater samples around the iceberg’s route to help determine what life could form around it and how the iceberg and others like it impact carbon in the ocean, Laura Taylor, a scientist working on the ship, told The Associated Press.

"We know that these giant icebergs can provide nutrients to the waters they pass through, creating thriving ecosystems in otherwise less productive areas. What we don’t know is what difference particular icebergs, their scale, and their origins can make to that process,” she said.

Such research offers not only information about icebergs but also broader global climate implications, Earth.com reported. "The story of A23a is intrinsically linked to the narrative of global warming. The increasing rate of iceberg calving in Antarctica raises concerns about the stability of ice shelves and the potential for accelerated sea-level rise," wrote the site's founder Eric Ralls.

Rsearchers: Mega iceberg shows signs of erosion

Last month, EYOS Expeditions arrived at iceberg A23a and used a drone to capture video and found significant erosion and transformation, expedition leader Ian Strachan told Earth.com. "We saw waves, a good three meters or four meters high, smashing into the berg… These were creating cascades of ice – a constant state of erosion," he said.

The drone footage and images showed how the iceberg was being reshaped with caves and arches, by waves hitting it. Eventually, the top layers will collapse.

More icebergs

Previous record-holding icebergs include A68, which measured about 2,240 square miles and broke off northwest Antarctica in July 2017, according to Earth.com. And A76, which measured 1,670 square miles and broke off the Weddell Sea ice shelf in May 2021, but subsequently broke into three pieces, the site said.

The largest iceberg ever recorded with satellite imagery is B15, which broke from southern Antarctica's Ross Ice Shelf in March 2000, and was 25 miles long and covered 4,250 square miles, according to Guinness World Records.

As for A23a, the iceberg "stands as a stark reminder of the Earth’s changing climate and the urgent need to understand and protect our planet’s polar regions," Ralls wrote. "In summary, the story of A23a is not just about a massive chunk of ice. The takeaway here is the interconnectedness of our global environment and the shared responsibility we hold in safeguarding it for future generations."

Contributing: The Associated Press

Follow Mike Snider on X and Threads: @mikesnider & mikegsnider.

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