NASA Spots Giant Antarctic Iceberg Turning Blue as It Nears Breakup

NASA's Earth Observatory has highlighted iceberg A-23A, now streaked blue by meltwater and nearing breakup. After calving from Antarctica in 1986, the berg once spanned about 4,000 km²; by early 2026, it had shrunk to ~1,180 km². Blue meltwater pools on its surface, visible in late-2025 NASA imagery, are being studied by scientists at NASA and NSIDC as indicators of its rapid decay.

A-23A's Final Voyage

According to NASA, as of late 2025, A-23A still ranked among the largest Antarctic icebergs, though much reduced in size. Now about 1,180 km², the berg drifts north toward South Georgia Island in the South Atlantic. Experts say it is already in relatively warm (~3°C) water and moving into warmer currents — an “iceberg graveyard”. Observers note A-23A is shedding large fragments; an AP report in 2025 listed pieces A23D, A23E and A23F breaking off. Scientists at NASA and the National Snow and Ice Data Center expect these processes to accelerate in the austral summer, effectively ending the four-decade journey of this “megaberg.”

Blue Meltwater and Iceberg Breakdown

The bright blue appearance is a result of meltwater pools that fill surface depressions. According to Ted Scambos (University of Colorado), cracks in the ice are enlarged by the weight of the water in them.

According to NSIDC's Walt Meier and UMBC's Chris Shuman, the flow of the meltwater is still controlled by the ancient glacial striations (linear ridges). Interestingly, a photo taken of an astronaut on Dec. 27, 2025, indicates that almost all of the uppermost portion will have turned into blue melt ponds.