Massive iceberg rapidly breaking apart in warmer waters
After almost four decades drifting since detaching from Antarctica, the enormous iceberg A23a, one of the largest and oldest ever recorded, is now disintegrating and could vanish completely within weeks.
Earlier this year, the iceberg weighed just under a trillion tonnes and was over twice the size of Greater London, making it one of the most formidable ice formations of modern times.
At one point, the massive iceberg threatened to interfere with penguin feeding grounds on a remote South Atlantic island, though it eventually moved away without causing long-term disruption.
Fragmentation accelerates
Analysis of satellite imagery by the EU’s Copernicus Earth observation program shows A23a has shrunk to less than half its original size but still covers 1,770 sq km (683 sq miles) and spans 60 km (37 miles) at its widest. In recent weeks, enormous chunks—each about 400 sq km—have broken off, while numerous smaller fragments, still large enough to endanger ships, scatter the surrounding waters.
Andrew Meijers, a physical oceanographer at the British Antarctic Survey, described the iceberg as “breaking up fairly dramatically” as it drifted northward. “It’s basically rotting from underneath. The water is far too warm for it to remain intact. Melting is ongoing,” he explained. “I expect within weeks it won’t be identifiable anymore.”
Four decades adrift
A23a calved from the Antarctic ice shelf in 1986 and remained grounded in the Weddell Sea for over 30 years. It broke free in 2020, traveling along “iceberg alley” in the South Atlantic, propelled by the Antarctic Circumpolar Current.
In March, the iceberg ran aground off South Georgia island, raising concerns it could disrupt feeding for local penguins and seals. By late May, it had freed itself and resumed its northward drift.
Recent satellite data reveal the iceberg has picked up speed in the last weeks, at times moving up to 20 km in a single day. Exposure to warmer waters and large waves has caused rapid disintegration.
A rare survivor
Scientists noted that A23a’s longevity was remarkable. “Most icebergs don’t make it this far. Its size allowed it to survive longer and travel farther than others,” said Meijers. However, once icebergs leave Antarctic waters, their eventual demise is inevitable.
While iceberg calving is a natural process, researchers warn that the rate of ice loss from Antarctica is increasing, likely accelerated by climate change.
