Iceberg A23a has turned blue and is "on the verge of complete disintegration," NASA said. This photo was taken on December 26, 2025. NASA

One of the largest and oldest icebergs ever tracked by scientists has turned blue and is "on the verge of complete disintegration," NASA said on Thursday.

A23a, a massive wall of ice that was once twice the size of Rhode Island, is drenched in blue meltwater as it drifts in the South Atlantic off the eastern tip of South America, NASA said in a news release.

A NASA satellite captured an image of the fading berg the day after Christmas, showing pools of blue meltwater on its surface. A day later, an astronaut aboard the International Space Station captured a photograph showing a closer view of the iceberg, with an even larger melt pool.

The satellite image suggests that the A23a has also "sprung a leak," NASA said, as the weight of the water pooling at the top of the berg punched through the ice.

Scientists say all signs indicate the so-called "megaberg" could be just days or weeks from totally disintegrating as it rides currents that are pushing it toward even warmer waters. Warmer air temperatures during this season could also speed up A23a's demise in an area that ice experts have dubbed a "graveyard" for icebergs.

"I certainly don't expect A-23A to last through the austral summer," retired University of Maryland, Baltimore County scientist Chris Shuman said in a statement.

Blue and white linear patterns visible on A23a are likely related to striations, which are ridges that were scoured hundreds of years ago when the iceberg was part of the Antarctic bedrock, NASA said.

"The striations formed parallel to the direction of flow, which ultimately created subtle ridges and valleys on the top of the iceberg that now direct the flow of meltwater," said Walt Meier, a senior research scientist at the National Snow & Ice Data Center.

When the berg detached from Antarctica in 1986, it was about 4,000 square kilometers and hosted a Soviet research station. It remained stuck for over 30 years before finally breaking free in 2020, its slow journey north sometimes held up by ocean forces that stopped its movement.

In 2023, the British Antarctic Survey posted a time-lapse of satellite imagery, showing the iceberg's movement. In January 2025, it was on a collision course with a remote penguin colony but fortunately, it did not make impact.

Last summer, multiple large chunks of ice broke off A23a as it moved into relatively warm summer conditions. According to current estimates from the U.S. National Ice Center, in early January 2026, the berg's area is 1,182 square kilometers -- still larger than New York City but a fraction of its initial size.

"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," said Shuman. "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."

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