Nearly 40 years after calving from the Filchner-Ronne Ice Shelf in Antarctica, A23a – once the largest and longest-lasting iceberg on Earth – is now rapidly breaking apart. Researchers estimate it may not survive beyond the end of November 2025, China Media Group reported.

Since calving in 1986, A23a has remained grounded in the Weddell Sea for more than 30 years, stuck on the ocean floor. Around 2020, the iceberg began drifting northward due to ice melt and other processes.

A23a experienced a massive rupture, reducing its area by nearly 20 percent in a single event, the Arctic and Antarctic Research Institute reported on September 11. With A23a now breaking apart, the 3,000-square-kilometer iceberg D15a has taken its place as the world's largest.

Scientists had previously predicted that as the Southern Hemisphere enters spring and ocean temperatures continue to rise, A23a would quickly fragment into smaller pieces.

Watch more: World's largest iceberg breaks apart