World’s largest iceberg A23a disintegrates after decades adrift

The world’s largest iceberg, Iceberg A23a, is rapidly breaking apart and has lost nearly all of its original size in recent months, according to Russia’s Arctic and Antarctic Research Institute.

Scientists report that the iceberg’s area has shrunk dramatically from around 1,300 square kilometres in January to less than 50 square kilometres, marking a loss of roughly 99% of its surface. 

Experts say the iceberg is continuing to fragment as it drifts through open waters. Polina Soloshchuk, chief specialist at the institute’s Centre for Ice and Hydrometeorological Information, noted that A23a has travelled approximately 1,000 kilometres over the past three months while actively disintegrating.

A23a has a long history dating back to 1986, when it broke away from the Filchner Ice Shelf. At the time of its formation, it covered an area of about 4,170 square kilometres, making it one of the largest icebergs ever recorded.

For decades, the massive ice block remained largely stationary in the Weddell Sea, effectively grounded and showing little movement. It was only in 2023 that the iceberg began drifting significantly, eventually entering warmer and more dynamic ocean conditions that accelerated its deterioration.

Researchers say such rapid disintegration is typical once large icebergs leave colder, stable waters and move into open seas, where higher temperatures, ocean currents and wave action contribute to their breakup.

While the melting of individual icebergs does not directly raise sea levels—since they are already floating—scientists monitor these events closely as indicators of broader changes in Antarctic ice dynamics and ocean conditions.

The collapse of A23a marks the end of a decades-long journey for one of Antarctica’s most notable ice formations, highlighting the fragile and evolving nature of polar environments.

By Sabina Mammadli