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.

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04 september 2025   |   08:22   |   Source: Gazeta Morska / PAP   |   Prepared by: Kamil Kusier   |   Print

fot. Wikimedia

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.

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góra lodowa A23a Antarktyda zmiany klimatyczne topnienie lodowców Ocean Południowy

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