Why the world’s largest iceberg has turned blue as scientists watch it fall apart

After drifting across Antarctic waters for nearly four decades, one of the most famous icebergs ever tracked is finally breaking apart. Once the largest iceberg on Earth, A-23A is now showing vivid blue tones that signal heavy melting. Scientists say its long journey is almost over.


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How did A-23A become the world’s largest iceberg?

A-23A first separated from Antarctica’s Filchner Ice Shelf in 1986, immediately becoming one of the largest icebergs ever observed. At its peak, it covered nearly 4,000 square kilometers, almost twice the size of Rhode Island, earning it global scientific attention for its immense scale and longevity, as per a report by the Express.

Why is the iceberg turning blue now?

The striking blue color is a visible sign of advanced melting. According to NASA Earth Observatory, the iceberg is now heavily waterlogged, with meltwater pooling across its surface. The agency noted, “After a four-decade run, the massive, waterlogged berg is leaking meltwater and on the verge of disintegrating.”

"One of the largest and longest-lived bergs ever tracked by scientists is sopping with blue meltwater and on the verge of complete disintegration as it drifts in the South Atlantic between the eastern tip of South America and South Georgia island."


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How fast is A-23A shrinking?

By early January 2026, the U.S. National Ice Center reported that A-23A had shrunk to just 1,182 square kilometers. Large fragments broke away during July, August, and September of 2025 after the iceberg drifted into warmer waters by December, accelerating its collapse.

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What do scientists expect next?

Experts believe A-23A’s end is imminent. NASA quoted retired University of Maryland scientist Chris Shuman, who said, “I certainly don't expect A-23A to last through the austral summer." Researchers say the iceberg may fully disintegrate within days or weeks, as per a report by the Express.

"A-23A faces the same fate as other Antarctic bergs, but its path has been remarkably long and eventful. It's hard to believe it won't be with us much longer."

Has another iceberg taken its place?

With A-23A fading, scientists say iceberg D15a—located near Australia’s Davis research station—has become the world’s largest, spanning roughly 3,000 square kilometers, as per a report by the Express.

FAQs

How old is iceberg A-23A?
It broke away from Antarctica in 1986, making it nearly 40 years old.

Why is its blue color important?
The blue shade indicates heavy meltwater buildup and advanced disintegration.