Antarctica: iceberg A23a in its final weeks
The world’s largest and one of the oldest icebergs – A23a, which calved from the Antarctic ice shelf in 1986 – is now in the final stage of its existence. According to Andrew Meijers, oceanographer at the British Antarctic Survey, the massive block of freshwater ice is expected to melt and vanish completely within the next few weeks. Speaking to AFP, he emphasized that the disintegration is accelerating due to unusually warm ocean waters in the Southern Ocean and the South Atlantic.
In brief
Iceberg A23a, which broke away from the Antarctic ice shelf in 1986, will melt completely within the coming weeks, forecasts oceanographer Andrew Meijers of the British Antarctic Survey. According to satellite data from the Copernicus programme, the area of A23a has fallen below half its original size, to about 1,770 square kilometres, and at its widest point the berg measures 60 km and moves at speeds of up to 20 km per day. In recent weeks fragments with a total area of more than 400 square kilometres have broken off and are drifting north, where they may threaten shipping lanes in the South Atlantic.
At the beginning of 2025, A23a was estimated to weigh just under one trillion tonnes, with a surface area more than twice the size of metropolitan London. Satellite observations by the EU’s Copernicus Earth Observation Programme now show the iceberg reduced to less than half of its original size – roughly 1,770 km², stretching about 60 km across at its widest point.
In recent weeks, large fragments covering around 400 km² have broken away, while additional sizeable pieces continue drifting northward. These ice masses are now regarded as potential hazards to commercial and research vessels navigating the South Atlantic. A23a itself is still moving at speeds of up to 20 km per day.
Earlier this year, the iceberg’s trajectory raised ecological concerns as it approached South Georgia Island, a key feeding ground for penguins and seals. By May, however, it passed the island without causing major disruption.
For researchers, A23a’s longevity remains remarkable. As Andrew Meijers noted:
– Most icebergs never make it this far. A23a was truly exceptional – its sheer scale allowed it to survive far longer and drift much farther than the vast majority. But once an iceberg leaves the protective cold waters of Antarctica, its fate is sealed.
While calving and drifting are part of the natural life cycle of icebergs, scientists stress that the rate of melting is being accelerated by human-driven climate change.
Source: Gazeta Morska / PAP · Compiled by: Kamil Kusier
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