By Dean Murray
A rare cloud-free image shows the first signs that the A23a iceberg, once the world’s largest, will soon disintegrate completely.
The newly released Copernicus Sentinel-2 satellite image was captured over the South Atlantic Ocean in December.
The bright blue areas visible on its surface and on the icebergs to its south are ponds of meltwater, which are clear signs of the iceberg’s rapid demise.
A23a calved from the Filchner-Ronne Ice Shelf in West Antarctica in 1986. At the time, it measured around 4000 sq km – more than three times the size of Rome – making it the largest iceberg in the world.
Although it has lost about three-quarters of its surface area, A23a is still one of the largest icebergs floating in open waters, covering roughly 1000 sq km.
After being grounded on the ocean floor for decades, in 2020 it lost its grip and began floating in the Weddell Sea until, in November 2023, it started drifting quickly away from Antarctic waters.
Driven by winds and currents, the iceberg traveled about 2000 km further north towards the warmer South Atlantic Ocean waters, reaching South Georgia Island in May 2025, where it started to disintegrate.
The European Space Agency (ESA) said Friday (Jan 16): “Throughout 2025, A23a has been breaking apart into smaller blocks of ice reducing its size significantly. In this image from 20 December 2025, the iceberg is approximately 150 km northwest of South Georgia, surrounded by numerous icebergs from different sizes.
“The disintegration is typical of icebergs that reach this far north and is caused by the warmer sea temperatures and weather conditions. As A23a is travelling towards even warmer waters pushed by the currents, it will soon experience a similar fate to other megabergs that have disintegrated in the same waters.”
It is believed that iceberg D15a, currently located near Australia’s Davis research station in Antarctica, is the current world’s largest. It measures around 3,000 sq km.
