A23a, the world’s largest iceberg, on collision course with South Georgia
The world’s largest iceberg, A23a, is steadily approaching South Georgia, a British overseas territory. The iceberg is currently about 280 km (173 miles) from the island and could make contact within 2 to 4 weeks.
Satellite image of Iceberg A23A recorded on January 23, 2025, shows its approximate dimensions of 74 x 59 km (46 x 37 miles). Image credit: US National Ice Center via Polar View, Sentinel-3 Mosaic, The Watchers
- The world’s largest iceberg, A23a, is moving toward South Georgia, a British overseas territory, and is expected to make contact within 2 to 4 weeks.
- Iceberg’s grounding near the island could block access to feeding grounds for penguins and seals.
- Researchers from the British Antarctic Survey (BAS) are studying the iceberg’s impact on ocean chemistry and nutrient cycling as melting icebergs release essential nutrients that influence marine ecosystems.
The world’s largest iceberg, A23a, is moving toward the British overseas territory of South Georgia in the South Atlantic Ocean. It is expected to make contact within 2 to 4 weeks, depending on ocean currents.
The iceberg is currently about 280 km (173 miles) from the island and measures approximately 3 500 km2 (1 351 mi2) with towering ice cliffs reaching 400 m (1 312 feet).
Scientists and conservationists are closely monitoring the situation as the massive iceberg can threaten local wildlife including colonies of king penguins and elephant and fur seals.
Impact on marine ecosystem and wildlife
Large icebergs like A23a pose threats to marine life when they ground near islands such as South Georgia. Icebergs can obstruct access to feeding grounds for seabirds and marine mammals leading to mass starvation events.
“Icebergs are inherently dangerous. I would be extraordinarily happy if it just completely missed us,” said Simon Wallace, captain of the South Georgia government vessel Pharos.
Past events demonstrate the dangers such massive icebergs present. In 2004, iceberg A38 grounded near South Georgia and disrupted food access for thousands of penguins and seals.
If A23a behaves similarly, it could have lasting ecological consequences for the island’s wildlife. Scientists predict that if it breaks apart upon contact, smaller icebergs could linger for years, further complicating local environmental conditions.
Scientific interests
The British Antarctic Survey (BAS) has been monitoring A23a by utilizing satellite imagery and oceanographic surveys.
Scientists aboard the research vessel RRS Sir David Attenborough collected water samples near the iceberg in December 2024 to study its impact on ocean chemistry and nutrient cycling.
“We took samples of ocean surface waters behind, immediately adjacent to, and ahead of the iceberg’s route. 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,” said Laura Taylor, a biogeochemist from the BAS.
As icebergs melt, they release nutrients such as iron and nitrogen into the surrounding waters which can stimulate phytoplankton blooms. These microscopic organisms play an important role in the marine food web and contribute to carbon sequestration. Researchers are keen to understand how A23a’s melting will influence the processes in the Southern Ocean.
The journey of A23a
The iceberg originally calved from Antarctica’s Filchner Ice Shelf in 1986 but remained grounded in the Weddell Sea for more than 30 years. It began drifting in 2020 but became trapped in an oceanic vortex known as a Taylor column near the South Orkney Islands in early 2024.
A23a broke free by December 2024 and resumed its northward journey toward South Georgia. Satellite tracking has since confirmed its steady movement and has raised concerns over its potential impact on the region.
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Collision or disintegration?
The precise behavior of A23a remains uncertain despite advanced tracking.
Ocean currents and temperature changes may alter its path while current projections suggest it could ground near South Georgia.
Smaller icebergs could disperse throughout the region if the iceberg breaks apart before reaching the island and can pose continued navigational hazards for ships and disrupt marine habitats.
A23a’s movement has drawn global attention not only because of its size but also because it shows the increasing instability of Antarctica’s ice shelves.
References:
1 World’s largest iceberg on collision course with British island – The Telegraph – January 23, 2025
2 Giant iceberg on crash course with island, putting penguins and seals in danger – BBC – January 22, 2025
Rishika holds a Master’s in International Studies from Stella Maris College, Chennai, India, where she earned a gold medal, and an MCA from the University of Mysore, Karnataka, India. Previously, she served as a Research Assistant at the National Institute of Advanced Studies, Indian Institute of Science, Bengaluru, India. During her tenure, she contributed as a Junior Writer for Europe Monitor on the Global Politics website and as an Assistant Editor for The World This Week. Her work has also been published in The Hindu newspaper, showing her expertise in global affairs. Rishika is also a recipient of the Women Empowerment Award at the district level in Haryana, India, in 2022.
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