The world’s largest iceberg, A23a, is on the move once again after a long period of being grounded. Researchers from the British Antarctic Survey (BAS) confirmed its drift across the Southern Ocean, marking a significant shift after decades of stasis. "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 have taken off Antarctica, and more important, what impact this will have on the local ecosystem," said Dr. Andrew Meijers, an oceanographer with BAS.
A23a weighs nearly one trillion tons and spans approximately 3,672 square kilometers (1,418 square miles), making it roughly twice the size of Greater London or slightly larger than Rhode Island. It has been the largest iceberg on Earth, maintaining its title amid competition. This massive iceberg calved from the Filchner-Ronne ice shelf of West Antarctica back in 1986 due to natural processes but immediately became lodged on the seabed north of the South Orkney Islands.
For over three decades, A23a remained stuck, transforming effectively from glacier to island as it became grounded. But as of 2020, the iceberg broke free, drifting through the Weddell Sea before encountering yet another hurdle. Scientists tracked it as it became trapped within a Taylor Column—a vortex phenomenon caused by underwater mountains, preventing it from drifting properly.
Now, following its escape from this predicament, researchers anticipate A23a will drift northward on the Antarctic Circumpolar Current toward warmer waters near South Georgia. There, it is expected to melt and break apart, forming smaller icebergs. This transition is of significant interest to scientists who are studying the effects of icebergs on marine ecosystems.
“We know these giant icebergs can provide nutrients to the waters they pass through, promoting ecosystems within otherwise less productive areas. What’s less understood is the specific impacts of different icebergs, their scale, and origins,” said biogeochemist Laura Taylor, involved with the project to study A23a. Researchers collected samples from the ocean surface behind, adjacent to, and near A23a’s route to help determine how marine life may thrive around it as it moves.
During their studies, scientists managed to photograph the iceberg and sample nearby waters from the RRS Sir David Attenborough, confirming hypotheses about how gigantic icebergs can shape local ecology. The iceberg’s movement through the environment holds clues to the influence of ice on nutrient cycles, carbon balance, and the state of marine life around Antarctica.
While A23a’s melting is unlikely to contribute significantly to rising sea levels, monitoring it closely is imperative for broader climate change studies. The interaction between A23a and warmer waters raises questions about how these dramatic shifts affect ice dynamics and biological processes within the Southern Ocean.
Dr. Meijers remains optimistic about this chance to study A23a closely, as it parallels other historical iceberg events surrounding Antarctica. "Icebergs can serve as laboratories for assessing environmental changes. We’re just beginning to understand what happens to marine ecosystems when massive icebergs begin to melt and break apart," he commented.
Each movement A23a makes may reveal patterns and provide valuable data to researchers examining the effects of climate change globally. The excitement surrounding A23a’s newfound mobility reflects the larger, urgent narrative about earth's polar regions, where change is occurring rapidly.
A23a will be watched closely as researchers continue to monitor its passage through the Southern Ocean, eager to glean insights from its interaction with the warmer waters near South Georgia. The study of icebergs like A23a provides not only scientific intrigue but also greater awareness of how dynamic Earth’s systems are, particularly those influenced by climate change.
