Iceberg A-23A turns blue as scientists warn collapse is imminent

A massive iceberg that broke away from Antarctica nearly four decades ago is showing dramatic signs of collapse, as scientists say its vivid blue color signals the final stage of its long journey.

Satellite images show iceberg A-23A, which calved from the Filchner Ice Shelf in 1986, has rapidly shifted from snowy white to bright cyan as meltwater pools across its surface. 

Researchers say the trapped water is accelerating the iceberg’s breakup as it drifts into warmer waters near the boundary of the Southern Ocean and South Atlantic.

“I certainly don’t expect A-23A to last through the austral summer,” said Chris Shuman, a retired Earth scientist formerly with the University of Maryland Baltimore County.

Unlike naturally blue icebergs formed through compression over time, scientists say A-23A’s color comes from surface melting. 

The iceberg remained grounded in the Weddell Sea for roughly 30 years before breaking free in 2023. 

It later became trapped in ocean currents and briefly grounded again in 2025 before beginning a rapid decline.

In January 2025, A-23A was still the world’s largest iceberg at 3,640 square kilometres. By September, it had shrunk to 1,700 square kilometres. 

As of January 9, 2026, satellite data shows it has reduced further to just 1,182 square kilometres.

NASA says the iceberg is “on the verge of complete disintegration,” noting that pooled meltwater is forcing open cracks from within. 

The iceberg is now drifting toward an iceberg graveyard near South Georgia Island, where it is expected to fully melt.

“I’m incredibly grateful that we’ve had the satellite resources in place that have allowed us to track it and document its evolution so closely,” Shuman said. 

“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.”