The Planet’s Largest Iceberg Is on the Loose

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After spinning in a vortex for months, the world’s largest and oldest iceberg is on the move again.

Researchers from the British Antarctic Survey announced on Friday that the colossal iceberg, designated A23a, is floating across the Southern Ocean. The iceberg’s journey provides a significant opportunity for scientists to study how giant icebergs impact their surrounding ecosystems.

“It’s exciting to see A23a on the move again after periods of being stuck. We are interested to see if it will take the same route the other large icebergs that have calved off Antarctica have taken,” Andrew Meijers, an oceanographer at British Antarctic Survey, noted in the British Antarctic Survey statement, “And more importantly what impact this will have on the local ecosystem.”

A23a weighs almost a trillion tons, and, as of August, spanned 1,418-square-miles (3,672 square kilometers), making it twice as big as Greater London, or just a bit larger than Rhode Island, according to CNN. It has repeatedly claimed the title of the world’s largest iceberg, outlasting several large contenders.

A23a separated from West Antarctica’s Filchner-Ronne ice shelf in 1986 as a result of natural processes, but almost immediately got lodged into the seafloor north of the South Orkney Islands. In 2020, it came free and floated in the Weddell Sea until it got trapped in a Taylor Column, a phenomenon in oceans that traps objects drifting over underwater mountains in water vortexes.

A23a recently escaped the rotating waters that kept it in place, according to BAS. Scientists expect the iceberg to drift along on the Antarctic Circumpolar Current towards the warmer waters around the island of South Georgia, where it will likely break up into countless smaller pieces and ultimately melt.

One year ago, British Antarctic Survey researchers observed A23a while studying polar ecosystems in the Weddell Sea for the BIOPOLE project. From the RRS Sir David Attenborough research vessel, they photographed the massive iceberg and collected samples from the waters in its proximity.

“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,” says Laura Taylor, a biogeochemist at BIOPOLE.

“We took samples of ocean surface waters behind, immediately adjacent to, and ahead of the iceberg’s route,” she adds. “They should help us determine what life could form around A23a and how it impacts carbon in the ocean and its balance with the atmosphere.”

It remains to be seen how long A23a will remain the world’s largest iceberg, and what its oceanic journey will reveal about Antarctic marine ecosystems. I have a feeling we’ve only hit the tip of the literal iceberg!



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