Iceberg A23a is a large tabular

iceberg An iceberg is a piece of fresh water ice more than long that has broken off a glacier or an ice shelf and is floating freely in open water. Smaller chunks of floating glacially derived ice are called "growlers" or "bergy bits". Much of an i ...

which calved from the

Filchner–Ronne Ice Shelf The Filchner–Ronne Ice Shelf or Ronne–Filchner Ice Shelf is an List of Antarctic ice shelves, Antarctic ice shelf bordering the Weddell Sea. Description The seaward side of the Filchner–Ronne ice shelf is divided into Eastern (Filchne ...

in 1986. It was stuck on the sea bed for many years but then started moving in 2020. its area is about , which makes it the current largest iceberg in the world. it has run aground off

South Georgia South Georgia is an island in the Atlantic Ocean, South Atlantic Ocean that is part of the British Overseas Territories, British Overseas Territory of South Georgia and the South Sandwich Islands. It lies around east of the Falkland Islands. ...

island. The base

Druzhnaya I Druzhnaya () may refer to: * Druzhnaya, Bryansk Oblast, a rural locality in Navlinsky District, Bryansk Oblast, Russia * Druzhnaya, Perm Krai, a rural locality in Bryukhovskoye Rural Settlement, Yelovsky District, Perm Krai, Russia * Druzhnaya, ...

, which was originally established on the Filchner–Ronne Ice Shelf, was situated on the iceberg when it calved. Subsequently, a rescue mission was started in 1987 and ultimately moved/renamed the base to Druzhnaya III. Iceberg A23a from 2011 to 2023

In November 2023, A23a was tracked moving past the northern tip of the

Antarctic Peninsula The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martin in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctica. ...

and heading towards the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the world ocean, generally taken to be south of 60th parallel south, 60° S latitude and encircling Antarctica. With a size of , it is the seco ...

. On 1 December 2023, the iceberg was intercepted by the polar research ship RRS ''Sir David Attenborough'', off the tip of the Antarctic Peninsula. At 10

knots A knot is a fastening in rope or interwoven lines. Knot or knots may also refer to: Other common meanings * Knot (unit), of speed * Knot (wood), a timber imperfection Arts, entertainment, and media Films * ''Knots'' (film), a 2004 film * ''Kn ...

, it took the ship several hours to sail along two sides of the iceberg. A23a is expected to release a significant quantity of

mineral dust Mineral dust is particulate, atmospheric aerosol originated from the suspension (chemistry), suspension of minerals constituting the soil, composed of various oxides and carbonates. Human activities lead to 25% of the fugitive dust, airborne du ...

as it melts, so the ship took water samples around its perimeter. On 14 January 2024, dramatic archways caused by wave action on A23a were documented by a drone operated by Eyos Expeditions videographer Richard Sidey and expedition leader Ian Strachan. Their footage was published widely by the

BBC The British Broadcasting Corporation (BBC) is a British public service broadcaster headquartered at Broadcasting House in London, England. Originally established in 1922 as the British Broadcasting Company, it evolved into its current sta ...

and

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. In early April 2024, the iceberg entered the Antarctic Circumpolar Current but stayed in place as it was trapped in a

Taylor column A Taylor column is a fluid dynamics phenomenon that occurs as a result of the Coriolis effect. It was named after Geoffrey Ingram Taylor. Rotating fluids that are perturbed by a solid body tend to form columns parallel to the axis of rotation c ...

—as confirmed in August 2024—over the Pirie Bank

seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...

near the

South Orkney Islands The South Orkney Islands are a group of List of Antarctic and sub-Antarctic islands, islands in the Southern Ocean, about north-east of the tip of the Antarctic Peninsula British Antarctic Survey The British Antarctic Survey (BAS) is the United Kingdom's national polar research institute. It has a dual purpose, to conduct polar science, enabling better understanding of list of global issues, global issues, and to provide an active prese ...

(BAS) reported that the iceberg had exited the Taylor column and was now beginning to drift further north through the Southern Ocean. The BAS expects A23a to follow the Antarctic Circumpolar Current towards the island of

in the southern Atlantic Ocean, where it will eventually encounter warmer water and break up into smaller icebergs. A23a is away from South Georgia and still on its way towards the island, potentially threatening the penguin and seal populations by blocking their access to feeding grounds. On March 4, 2025 it was reported that A23a had grounded from South Georgia, marking the end of its drift since 2020 before it accelerated and then abruptly stopped near the island. Some scientists say it could threaten local wildlife by blocking key feeding grounds for penguins and seals, though others say they don't expect it to significantly affect wildlife. Scientists warn that its melting could disrupt marine ecosystems by altering nutrient flows and krill populations, though it was also pointed out that its grounding will stir up nutrients from the seafloor and may boost the regional ecosystem. The event underscores the broader impact of climate change on Antarctic ice loss, with researchers closely monitoring its effects on biodiversity and regional stability.

References

1986 in Antarctica Icebergs History of South Georgia Filchner-Ronne Ice Shelf Bodies of ice of Queen Elizabeth Land {{Antarctica-stub

See also

References