Thomas Unise
A massive Antarctic iceberg known as A-23A, which broke off from the ice sheet in 1986, is displaying alarming signs of imminent disintegration as it turns a vivid blue color. NASA satellite images reveal this concerning development in one of the world’s oldest tracked icebergs.
The Shrinking Giant
When A-23A first detached in 1986, it measured twice the size of Rhode Island. By January 2025, it still covered approximately 1,410 square miles, earning the Guinness world record for the largest existing iceberg. However, it has dramatically shrunk to just 456 square miles (roughly Manhattan-sized) by early 2025 following several major calving events over the past year.
Blue Meltwater Signals Imminent Collapse
Recent NASA Terra satellite images from December 26 show the iceberg “sopping with blue meltwater” as it drifts near South America’s southern tip. Scientists explain that these blue pools visible on the surface are clear indicators of “ongoing disintegration events.”
Ted Scambos, a senior research scientist at the University of Colorado Boulder, explained that “the weight of the water sitting inside cracks in the ice” is forcing these cracks open, accelerating the iceberg’s breakup.
Ancient History Revealed
Particularly fascinating are the blue diagonal stripes visible in satellite imagery. Experts believe these are scour marks dating back hundreds of years to when A-23A was dragged across Antarctic bedrock. Walt Meier from the National Snow & Ice Data Center notes that these striations “formed parallel to the direction of flow” and now channel meltwater across the iceberg’s surface.
Final Days Approaching
Scientists believe A-23A may completely disintegrate within weeks or months. Chris Shuman, a retired scientist from the University of Maryland Baltimore County, told NASA: “I certainly don’t expect A-23A to last through the austral summer.” With temperatures already about three degrees Celsius warmer than expected, this process could accelerate further.
A Long Journey
A-23A’s journey has been remarkable. After breaking free in 1986, it remained near the Antarctic ice shelf until 2020, when it began drifting and spinning in deeper waters. Last year, it nearly collided with South Georgia island.
Climate Context
While A-23A’s original calving 40 years ago isn’t attributed to human-induced climate change, it serves as a reminder that we will continue to see massive icebergs breaking off from Antarctica as global temperatures rise and ocean waters warm. Scientists are racing to better understand how these icebergs behave and how shrinking glaciers due to global warming affect their behavior.
NASA described watching A-23A’s final days as a “bittersweet moment” in the study of these massive ice formations.
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