A-23A, the largest iceberg currently afloat on Earth, is undergoing a slow but relentless disintegration while stranded near South Georgia Island in the South Atlantic Ocean. Despite its immense size, the aging colossus is rapidly losing mass as environmental forces chip away at its once-intact edges.
According to an analysis published by NASA Earth Observatory on May 3, 2025, satellite imagery shows that A-23A has remained motionless in the waters near South Georgia since at least early March. While its position has hardly changed, its shape and mass certainly have. Over a span of just two months, the iceberg lost over 360 square kilometers of ice—an area approximately twice the size of Washington, D.C.
A Grounded Giant in Decline
A-23A is not drifting freely like many of its counterparts. It is grounded, likely lodged on a shallow underwater shelf that surrounds South Georgia Island. These shallows are notorious among scientists for ensnaring Antarctic icebergs on their way northward into warmer waters. This iceberg, which broke away from the Filchner Ice Shelf in 1986, has spent nearly four decades in the Southern Ocean, but its time appears to be drawing to a close.
“The berg’s underside is most likely lodged on a shallow underwater shelf around South Georgia, known in the past to have snagged several Antarctic icebergs on their northward drift into warmer South Atlantic waters,” wrote Kathryn Hansen in the NASA Earth Observatory article. The current stalling of A-23A aligns with well-documented patterns where large icebergs become temporarily fixed in this region before eventually melting away.
Edge Wasting and Structural Fragility
Recent imagery captured by NASA’s MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Aqua satellite has shown clear evidence of a specific type of iceberg deterioration known as edge wasting. This process occurs when small fragments calve off randomly from the periphery of an iceberg, reducing its total surface area while preserving its general shape. It contrasts with other breakup modes such as full structural fracturing or total disintegration.
There are visible signs that A-23A is becoming increasingly fragile. Along its northern edge, a band of bright ice debris indicates a sudden, recent edge wasting event, possibly triggered by several days of unusually sunny, warm weather. At a latitude near 55°S, the iceberg is now far removed from the frigid waters that helped preserve it for decades, leaving it more vulnerable to rapid weakening.
Shedding Bergs and Shipping Threats
Though the primary iceberg has shrunk, it remains surrounded by thousands of smaller fragments, many of which span over a kilometer across. These ice shards, though visually unimpressive from a satellite view, pose a serious navigational risk to ships transiting the area. One particularly large fragment, designated A-23C, detached from the southern edge of the main iceberg in mid-April and was substantial enough to receive an official name from the U.S. National Ice Center (USNIC).
This ongoing fragmentation highlights the dynamic nature of the iceberg’s deterioration. While shedding has occurred throughout its journey—including during its previous spin through the Drake Passage in 2024—the frequency and scale of recent calving events suggest that the structure of A-23A may be nearing a critical point.
The Standard Path to Destruction
The final chapter of A-23A fits a well-known trajectory. More than 90 percent of icebergs calving from Antarctica follow a broadly similar path: they enter the Weddell Gyre, are propelled northward along the Antarctic Peninsula, and cross the Drake Passage into the warming waters of the South Atlantic. This route ultimately leads to their disintegration and melting. A-23A has defied the timeline longer than most, but it now appears to be nearing the endpoint of that journey.
As it continues to erode in place, A-23A offers researchers and satellite observers a compelling live case study of large-scale iceberg decay in a warming world. The scene off South Georgia, now littered with floating ice fragments, is both majestic and foreboding—an evolving graveyard of ancient ice that signals not only the collapse of a physical structure, but the broader story of change in Earth’s polar systems.
