A23a megaberg rapidly disintegrating as it drifts into warmer South Atlantic waters
Scientists say the once trillion-ton iceberg has crumbled to less than half its original size and could vanish within weeks
The iceberg known as A23a, long ranked among the largest and oldest megabergs on record, is breaking apart as it drifts north into warmer South Atlantic waters and could disappear within weeks, scientists said.
British Antarctic Survey physical oceanographer Andrew Meijers said the iceberg has been "breaking up fairly dramatically" and is "very much on its way out... it's basically rotting underneath," as ocean temperatures well above those in Antarctic waters accelerate melting.
At the start of the year the berg was reported to be more than twice the size of Greater London. Satellite imagery captured on Aug. 19 shows its distinctive tooth-like shape becoming increasingly slender and fractured. Meijers said the iceberg is now about 683 square miles in area and roughly 37 miles at its widest point, less than half its original size.
Researchers and oceanographers monitoring A23a say the berg has been exposed to progressively warmer surface waters and large ocean swell as it moved northward, conditions that promote rapid disintegration. "The water is way too warm for it to maintain. It's constantly melting," Meijers said.
A23a has been tracked by satellite and by private and scientific vessels as it has traveled through the South Atlantic for months. Such megabergs can persist for years when they remain in cold polar waters, but their structural integrity weakens once they encounter milder seas and wave action, which can drive fracturing, calving and basal melting.
The scale of A23a drew attention because of its size and longevity. Descriptions in media accounts referred to the iceberg as a "trillion-ton" megaberg, underscoring its once-enormous mass and the significance of its ongoing loss. Scientists caution that while large bergs can break apart into many smaller pieces, their melting in warmer waters adds freshwater to ocean surface layers and alters local sea conditions.
Monitoring agencies continue to follow the fragments of A23a for navigational safety and scientific interest. Satellite-based observation remains the primary means of tracking these remote features, with imagery used to assess changes in shape, area and breakup patterns.
Experts said the fate of A23a illustrates the vulnerability of Antarctic ice once it leaves the cold, stabilizing influence of polar waters. The rapid decline of a prominent iceberg provides a focused example of processes that are increasingly relevant to oceanography and climate science, as changing ocean temperatures and circulation influence the lifecycle of ice masses calved from polar regions.
Scientists emphasized that observations of individual icebergs like A23a help refine understanding of how ice interacts with ocean conditions and waves, but cautioned against using a single event to draw broad conclusions about long-term trends without comprehensive analysis across regions and timeframes. Monitoring will continue as A23a's remaining fragments are expected to disperse or melt entirely in the coming weeks if current conditions persist.