Nearly 40 years after breaking off from Antarctica, one of the world’s largest and oldest icebergs is rapidly disintegrating in warmer waters and could vanish within weeks, scientists say.
The iceberg, known as A23a, originally calved from the Antarctic shelf in 1986. Weighing nearly a trillion tonnes and spanning more than twice the size of Greater London at its peak, it was considered one of the most massive icebergs ever recorded.
For more than 30 years, A23a remained grounded in the Weddell Sea before breaking free in 2020. Since then, it has drifted along “iceberg alley,” carried by the powerful Antarctic Circumpolar Current into the South Atlantic Ocean.
Rapid Breakup
According to satellite images analyzed by the EU Earth observation program Copernicus, A23a now measures about 1,770 square kilometers (683 square miles)—less than half its original size. In recent weeks, massive chunks, some measuring around 400 square kilometers, have broken off, while smaller fragments still large enough to threaten ships scatter the surrounding sea.
Andrew Meijers, a physical oceanographer with the British Antarctic Survey, told AFP the iceberg is “breaking up fairly dramatically” as it drifts into warmer waters.
“It’s very much on its way out … it’s basically rotting underneath,” Meijers said. “The water is way too warm for it to maintain. I expect it won’t be really identifiable within a few weeks.”
Environmental Concerns
Earlier this year, A23a briefly grounded off South Georgia island, raising fears it could block access to feeding grounds for penguins and seals. But the iceberg eventually dislodged and continued northward, picking up speed—at times drifting up to 20 km per day.
While icebergs naturally calve from Antarctica, scientists warn the rate of loss is accelerating, likely driven by human-induced climate change.
Why A23a Stood Out
- Calved in 1986 but remained stuck for three decades.
- Freed in 2020, embarking on a rare long-distance drift.
- At peak size, weighed nearly a trillion tonnes.
- Surprised scientists by lasting far longer and traveling farther than most icebergs.
Ultimately, researchers say, all icebergs that leave Antarctic waters are “doomed” to melt. A23a’s long life highlights both the resilience and fragility of these frozen giants.