The world’s most enduring and once-largest iceberg, A23A, is now in its final act. As of early September 2025, scientists have confirmed that the colossal slab of ice is splintering into smaller pieces at an accelerating pace, losing its long-held title as the largest iceberg afloat. The drama is unfolding in the frigid waters near South Georgia Island, off the coast of Antarctica, where A23A’s slow-motion demise offers both a spectacle and a reminder of the continent’s ever-changing landscape.
For nearly four decades, A23A was a fixture on the Antarctic stage. Its story began in 1986, when it broke away from the Filchner–Ronne Ice Shelf, following a massive crack dubbed “the Grand Chasm” that scientists first spotted in the 1950s. At the time, the event was noteworthy but not unprecedented; Antarctica has always been a place of shifting ice. Yet, what set A23A apart was its sheer size and longevity. Earlier this year, the iceberg was as large as the state of Rhode Island, weighing in at a staggering trillion tons. But by September, it had shrunk to roughly the size of Houston—and the shrinking isn’t over yet.
NASA satellite images from September 1, 2025, show the dramatic transformation. Where once there was a single, monolithic berg, now there are several smaller chunks—officially named A23D, A23E, and A23F—calving off from the main body. The images capture a process that, while natural, is happening at a pace that’s left even veteran ice scientists watching with bated breath.
“It’s an interesting thing to watch, certainly not unprecedented,” University of Colorado ice scientist Ted Scambos told The Associated Press. “But every time these happen, it’s sort of a big spectacular event.” Scambos, who has tracked Antarctic ice for decades, explained that A23A is being flexed by long-period waves and tides, which sweep across the region. “And with that flexing, even though it’s incredibly gentle and subtle, it’s finding weak spots in the iceberg, and those are breaking off.”
As the Antarctic spring begins, the iceberg’s fate looks increasingly grim. Andrew Meijers of the British Antarctic Survey expects the fracturing to accelerate. “I expect its fracturing will accelerate,” Meijers said in an email to AP. He predicts that by the end of the season, A23A will likely break into pieces too small to track. If it somehow survives the spring, the summer of 2026 could be even more brutal. That’s when warmer waters—sometimes even reaching the top of the berg—could trigger a rapid, avalanche-like collapse, possibly in just a single day. “It will then look sort of like an avalanche that’s floating,” Scambos said, painting a vivid picture of the potential endgame.
This isn’t just a story of one iceberg’s demise; it’s also about the larger dance of ice and water at the bottom of the world. For decades, A23A hovered close to Antarctica, relatively uneventful, until recent years when it drifted north toward the place where massive icebergs go to die—around South Georgia Island. This region is notorious among scientists as an iceberg graveyard, where currents and warmer waters work together to break down even the mightiest slabs of ice.
As A23A dwindles, a new giant has claimed the crown. Britain’s D15A iceberg is now the largest floating ice chunk in the world, nearly twice the size of the diminished A23A, according to Meijers. The handover is more than symbolic; it’s a reminder that Antarctica’s ice is in constant flux, driven by both natural cycles and, increasingly, the warming climate.
But what does this mean for the rest of the planet? The immediate answer is: not much, at least in terms of sea-level rise. As Scambos and other scientists have emphasized, ice shelves like A23A already float on water, so their melting doesn’t directly raise ocean levels. “Because ice shelves already float on water, ice reductions like this won’t raise the sea level,” Scambos explained. However, there’s a crucial caveat. The loss of these floating ice shelves can allow land-based glaciers behind them to flow more freely into the sea, and that does lead to rising waters—by a few feet (or meters) over time.
“Scientists stress that icebergs breaking apart do not raise sea levels directly. But shrinking ice shelves can allow land-based glaciers to melt faster into the ocean, which does contribute to rising seas,” reported the Associated Press. This chain reaction is a key concern for climate researchers, as the Antarctic continent holds enough ice to raise global sea levels by many meters if it were all to melt.
Despite the spectacle, scientists like Meijers and Scambos emphasize that megabergs spawning and breaking apart is a natural process that has happened for centuries. Still, each event is unique, and A23A’s slow-motion collapse is being watched closely for clues about the future of Antarctic ice. “Megabergs spawning is a natural process that has happened for centuries,” Meijers said, “and so is their breaking apart around South Georgia Island when the current and warmer waters get hold of them,” Scambos added.
Back in January, Meijers visited A23A and described the scene in dramatic terms: “The iceberg itself is colossal and it stretches from horizon to horizon ... It’s a huge wall, a Game of Thrones style wall of ice that towers above the ship.” That wall is now crumbling, a process captured in real time by satellites and scientists alike.
The story of A23A is a testament to the power and unpredictability of nature. It’s also a reminder that, while some changes in Antarctica are part of ancient cycles, others may be hastened by a warming world. As A23A continues its death spiral, scientists will be watching closely to see what comes next—and what it might mean for the future of Earth’s polar regions.
For now, the world watches as A23A, once the titan of the Southern Ocean, breaks apart piece by piece. Whether it collapses in a single dramatic day or continues to fragment over weeks, its end marks the close of a remarkable chapter in Antarctic history—and the beginning of new questions about the fate of the world’s ice.
