World’s Largest Iceberg A23a Disappears

The A23a iceberg, once the world’s largest and one of Antarctica’s longest-lived icebergs, has completely disintegrated and is no longer visible in satellite imagery.

The iceberg was last observed in April 2026, after which its remaining fragments broke apart and melted due to the combined effects of warm ocean currents and rising surface air temperatures.

A23a had existed for nearly 40 years after calving from the Filchner-Ronne Ice Shelf in 1986.

At its peak, the iceberg covered approximately 3,500 square kilometres, making it about twice the size of London and three times the size of New York City. It was estimated to weigh nearly one trillion tonnes.

During its journey, A23a travelled nearly 2,300 kilometres across the Antarctic coastline and the Southern Ocean before gradually disintegrating.

For nearly 30 years, the iceberg remained grounded on the seabed near the Weddell Sea. In 2022, it finally broke free and drifted northward into the South Atlantic Ocean, where it was monitored by NASA’s MODIS satellite.

During its drift, A23a narrowly avoided colliding with the ecologically sensitive South Georgia Island, home to large colonies of penguins and seals.

The iceberg gained historical significance because it was among the first giant Antarctic icebergs to be extensively monitored, and because the Soviet research station Druzhnaya-1 was located on it when it calved in 1986.

Scientists have also drawn parallels with India’s first Antarctic research station, Dakshin Gangotri, which was built on an ice shelf and was eventually buried under snow in the late 1980s.

About A23a Iceberg

• Origin: Calved from the Filchner-Ronne Ice Shelf, Antarctica, in 1986
• Naming: Named A23a based on the Antarctic quadrant in which it was first identified.
• Peak size: Around 3,500 sq. km
• Estimated weight: Nearly 1 trillion tonnes
• Time grounded: Nearly 30 years near the Weddell Sea
• Movement: Began drifting in 2022 toward the South Atlantic Ocean
• Fate: Completely fragmented and melted by 2026.

About Iceberg Calving

• Calving is the natural process by which large blocks of ice break away from glaciers or ice shelves, forming icebergs.
• While calving is a normal part of the Antarctic ice cycle, rising ocean temperatures and climate change can accelerate the melting and breakup of icebergs after they enter warmer waters.

Source: ToI

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