The iceberg A23a, known as the largest ice block on our planet for decades, has disappeared after nearly 40 years of existence. This colossal iceberg, which reached up to 3900 square kilometers, dissolved in the South Atlantic after a year of fractures and accelerated melting, a phenomenon that scientists have closely monitored to better understand the effects of climate change on ice formations.
The A23a: from calving to melting in the Atlantic
The gigantic A23a originated in 1986 when it calved from the Filchner Ice Shelf, along with its sibling icebergs, A22 and A24. While these moved towards warmer waters and disintegrated, A23a remained grounded on the seabed, in cold and stable waters, for more than three decades.
In 2020, the iceberg showed signs of movement. Its base began to melt, freeing it from its long-standing anchor. This process marked the beginning of its drift northeastward, a journey that took it near South Georgia, a region known for its shallow continental shelf.
In April 2024, A23a entered the Antarctic Circumpolar Current, but got trapped in a vortex of turbulent water called a Taylor column. This phenomenon kept it spinning for eight months, eroding its edges and widening its cracks.
The last months of its existence were intensely monitored. Scientific teams used satellites like Copernicus Sentinel-3 and NASA’s Terra to record its massive reduction. A23a had lost half of its original size, although it still retained a recognizable shape.
The environmental impact of its dissolution generated contrasting opinions among the scientific community. Some experts warned about the potential damage to marine ecosystems due to the disintegration of this ice giant, while others argued it was part of a natural polar cycle that could even fertilize the ocean by releasing accumulated nutrients.
Finally, at the beginning of 2026, A23a fragmented into smaller blocks, designated as A23g, A23h, and A23i. By March, its surface had decreased to about 180 square kilometers, with the last remnants of one of the most observed icebergs on the planet disappearing.
