China satellites track giant iceberg's end

China's Fengyun meteorological satellites have documented the disintegration of what was once the world's largest iceberg, A23a, the China Meteorological Administration said.

The largest remaining fragment now measures only 11 kilometers in length, with its area reduced to 35.2 square kilometers, no longer meeting the criteria for classification as an iceberg, marking the end of its 40-year existence.

Since late 2022, A23a accelerated its drift until it could no longer be tracked as an independent iceberg. Its final phase was comprehensively documented by Fengyun satellites.

A23a broke away from the Filchner Ice Shelf in Antarctica in 1986, initially covering an area of 4,170 square kilometers, with a thickness of nearly 400 meters and a total weight of approximately one trillion tons.

A research team led by Zheng Zhaojun, chief expert at the National Satellite Meteorological Center's International User Service Center, used remote sensing data from Fengyun satellites to monitor A23a's trajectory, morphological changes and disintegration process over the years.

Monitoring showed that A23a, which had long been grounded in the Weddell Sea, began to detach from the seafloor due to melting ice around 2020, though it remained largely stationary.

It was not until late 2022 that significant movement was observed. In early 2023, A23a's area was 4,035 square kilometers, earning recognition by Guinness World Records as the world's largest iceberg at the time. It then began accelerating, leaving the Weddell Sea in 2024 and entering the Antarctic Circumpolar Current.

Between June and September 2025, the iceberg experienced several large-scale fractures during its northward drift, reducing its area from 3,536 square kilometers at the start of the year to about 1,400 square kilometers. By January 2026, further disintegration left the main body at just 503 square kilometers.

Subsequently, propelled by the Antarctic Circumpolar Current, A23a drifted rapidly, undergoing three more collapses in its final phase.

A23a completed its final breakup between late March and early April, according to data from Fengyun-3 meteorological satellites. By April 3, its area had shrunk sharply to 35.2 square kilometers after a final collapse event.

For monitoring massive icebergs in polar and near-polar waters, the Fengyun-3 series satellites have demonstrated clear advantages, particularly through the onboard Medium Resolution Spectral Imager, or MERSI. With a spatial resolution of about 250 meters, the instrument allows scientists to observe both the overall shape of an iceberg and finer surface details.

These observations revealed increasing structural instability within the iceberg, offering clues to the processes that eventually led to its rapid disintegration, according to the center.

Researchers also detected notable ecological changes in the surrounding ocean during the iceberg's final breakup phase.

Since late 2025, satellite imagery has shown a gradual "greening" of waters in the fragmented ice zone around A23a, with green plumes expanding and shifting over time.

The discoloration of the sea surface is closely linked to phytoplankton blooms triggered by the influx of meltwater. The team is conducting further analysis to better understand the ecological effects associated with iceberg melt in polar regions, Zheng said.

The satellite observations are expected to provide valuable data for future studies of polar ecosystems, he added.