After a nearly 40-year journey, the world’s largest iceberg, A23a, is rapidly breaking apart in the warmer waters of the South Atlantic. The colossal “megaberg,” once twice the size of Greater London, is now shedding enormous chunks and is expected to disappear completely within weeks, marking the end of an era for one of the oldest and largest icebergs ever recorded.
The gigantic slab of ice originally broke off from Antarctica’s Filchner Ice Shelf in 1986 but spent over three decades grounded on the floor of the Weddell Sea before finally beginning its odyssey in 2020. According to a report from The Guardian, A23a has now lost more than half its size. Andrew Meijers, a physical oceanographer with the British Antarctic Survey, told reporters the iceberg is “breaking up fairly dramatically” as it drifts north, adding that it’s “basically rotting underneath” in water that is “way too warm for it to maintain.”
While the life cycle of an iceberg is a natural process, A23a’s demise occurs against a backdrop of accelerating and “abrupt changes” across the Antarctic region. Scientists have noted that the rapid loss of protective sea ice around the continent exposes larger, more critical ice shelves to the erosive power of warmer ocean water and waves. This instability is a growing concern, especially since climate projections have historically underestimated the contribution of melting ice sheets to global sea-level rise, a phenomenon that is now unfolding with potentially irreversible consequences.
