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A23a
Large iceberg in Antarctica From Wikipedia, the free encyclopedia
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Iceberg A23a is a large tabular iceberg which calved from the Filchner–Ronne Ice Shelf in 1986. It was stuck on the sea bed for many years but then started moving in 2020. As of January 2025,[update] its area is about 3,500 square kilometres (1,400 sq mi), which makes it the current largest iceberg in the world.[1][2][3] As of March 2025,[update] it has run aground off South Georgia island.[4]
Drift of A23a (map data)
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The base Druzhnaya I, which was originally established on the Filchner–Ronne Ice Shelf, was situated on the iceberg when it calved.[2] Subsequently, a rescue mission was started in 1987 and ultimately moved/renamed the base to Druzhnaya III.[5]
In November 2023, A23a was tracked moving past the northern tip of the Antarctic Peninsula and heading towards the Southern Ocean.[7] On 1 December 2023, the iceberg was intercepted by the polar research ship RRS Sir David Attenborough, off the tip of the Antarctic Peninsula.[8] At 10 knots, it took the ship several hours to sail along two sides of the iceberg.[8] A23a is expected to release a significant quantity of mineral dust as it melts, so the ship took water samples around its perimeter.[8]
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 and CNN.[9] In early April 2024, the iceberg entered the Antarctic Circumpolar Current but stayed in place as it was trapped in a Taylor column—as confirmed in August 2024—over the Pirie Bank seamount near the South Orkney Islands about 375 miles from the Antarctic Peninsula, turning counterclockwise by around 15 degrees every day.[10][11][12] In December 2024, the British Antarctic Survey (BAS) reported that the iceberg had exited the Taylor column and was now beginning to drift further north through the Southern Ocean.[13]
The BAS expects A23a to follow the Antarctic Circumpolar Current towards the island of South Georgia in the southern Atlantic Ocean, where it will eventually encounter warmer water and break up into smaller icebergs.[14][1] As of 23 January 2025,[update] A23a was 173 miles (278 km) away from South Georgia and still on its way towards the island.[1]
On March 4, 2025 it was reported that A23a had grounded 73 km (45 mi) from South Georgia, marking the end of its drift since 2020 before it accelerated and then abruptly stopped near the island.[15] Some scientists say it could threaten local wildlife by blocking key feeding grounds for penguins and seals,[16] though others say they don't expect it to significantly affect wildlife.[15] 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.[15] The event underscores the broader impact of climate change on Antarctic ice loss, with researchers closely monitoring its effects on biodiversity and regional stability.
On July 31st, 2025 Iceberg A23a is reported 145 km East-SouthEast of South Georgia.[16]
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See also
Wikimedia Commons has media related to Iceberg A23a.
- A-76, largest iceberg for several months in 2021
- B-15, largest recorded iceberg with precise measurements
- 2025 in Antarctica
References
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