The year that iceberg A-23A first broke away from Antarctica’s Filchner Ice Shelf, Ronald Reagan was president of the United States, and the movie Top Gun was setting box office records. Forty years later, the massive tabular berg—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.
When it first detached from Antarctica in 1986, the berg was nearly twice the size of Rhode Island—about 4,000 square kilometers. Estimates from the U.S. National Ice Center put the berg’s area at 1,182 square kilometers (456 square miles) in early January 2026, following the breakup of several sizable pieces in July, August, and September of 2025 as it moved into relatively warm summer conditions by December.
When the MODIS (Moderate Resolution Imaging Spectroradiometer) on NASA’s Terra satellite captured this image of what remained of the waterlogged berg on December 26, 2025, extensive pools of blue meltwater were visible on its surface. Though much smaller than it once was, what remains is still among the largest icebergs in the ocean, covering an area larger than New York City. An astronaut aboard the International Space Station captured a photograph showing a closer view (below) of the iceberg a day later, with an even more extensive melt pool.
The “blue-mush” areas are likely the result of ongoing disintegration events, explained Ted Scambos, a senior research scientist at the University of Colorado Boulder. “You have …