Recently, A23a, which once held the title of the world's largest iceberg, disintegrated again. The largest fragment left behind was only 11 kilometers in length and an area of only 35.2 square kilometers. It no longer met the iceberg numbering standards and was therefore "deregistered."In 1986, A23a broke off from the Filchner Ice Shelf in Antarctica. It initially covered an area of 4,170 square kilometers, was nearly 400 meters thick, and weighed about 1 trillion tons. It was a giant glacier.
It is 4,170 square kilometers, equivalent to 7 Singapore and 2/3 Shanghai. It takes about 2.5 hours to drive around at a speed of 100 kilometers per hour.
The National Satellite Meteorological Center (National Space Weather Monitoring and Early Warning Center) International User Service Center is based on remote sensing data such as Fengyun Meteorological Satellite and has long-term tracking and monitoring of A23a's movement trajectory, morphological changes and disintegration process.
After the formation of A23a, it was stranded in the Weddell Sea on the edge of the South Atlantic and Antarctica for a long time. It was not until around 2020 that it was freed from the constraints of the seabed due to the melting of the ice. However, the movement speed was very small and it basically stagnated. There was no obvious movement until the end of 2022.
At the beginning of 2023, A23a had an area of 4,035 square kilometers and was recognized by Guinness World Records as the world's largest iceberg at that time.
But just then, it started to speed up,It will leave the Weddell Sea in 2024 and enter the westerly drift zone - the Antarctic Circumpolar Current.
From June to September 2025, A23a experienced multiple large-scale fractures while moving northward, and its area shrank from 3,536 square kilometers at the beginning of the year to about 1,400 square kilometers.
In January 2026, A23a disintegrated again, leaving only 503 square kilometers in area.
The drift path of the A23a iceberg based on Fengyun satellite monitoring (the dots indicate the location of the iceberg, and the time corresponds to the label on the right; the background color and arrows indicate ocean currents)
Subsequently, the A23a iceberg drifted rapidly driven by the Antarctic Circumpolar Current and completed three collapses at the end of its life.
The iceberg drift path and area changes monitored by the Fengyun Meteorological Satellite showed that A23a gradually accelerated its movement northward in mid-January; in mid-February, after encountering a strong east-west ocean current near 49 degrees south latitude, it turned eastward and drifted at a high speed, moving 473 kilometers in 7 days.
During this period, the area of A23a iceberg remained at about 500 square kilometers.
Area changes of A23a iceberg in 2026 based on Fengyun satellite monitoring
The first collapse occurred at the end of February 2026. A23a turned and moved southwest, and its area continued to decrease. On February 25, the area was 310 square kilometers.
After only being stable for a few days, a second collapse occurred, reducing the area to 180 square kilometers on March 3.
A week later, it turned to move eastward, and until the end of March and early April, it completed the final collapse marking the "iceberg cancellation" near 48.5 degrees south latitude and 30.5 degrees west longitude. The area plummeted from 169 square kilometers on March 27 to 35.2 square kilometers on April 3.
at this time,The largest complete fragment of the iceberg remnant has a long axis of 11 kilometers and an area of 35.2 square kilometers, falling below the iceberg numbering thresholds of 10 nautical miles (18.5 kilometers) and an area of 20 square nautical miles (68.6 square kilometers) respectively.
At this point, A23a Iceberg has officially been "cancelled".
For such long-lived, large-scale, and rapidly calving polar or near-polar giant icebergs,The 250-meter Moderate Resolution Spectroscopic Imager (MERSI) carried by the Fengyun-3 series of meteorological satellites shows the dual monitoring advantages of "macro situation + micro details".
Despite cloud interference, MERSI true color imagesIt relatively clearly records the shape changes and surface melting details of A23a before its terminal collapse., revealing that the internal structure of the iceberg is increasingly unstable, paving the way for eventual collapse.
On February 17, although the iceberg had "slimmed down" significantly, the main body was still intact; on the 22nd, except for the north side, large areas of calving occurred around it, especially in the east and south, where many contiguous dense ice fragments appeared; on the 25th, the remaining main body was obviously separated from the calved ice fragments; in March On the 1st, the main outline of the iceberg became clearer; on the 3rd, a large-scale collapse occurred in the north again. After many days of cloud cover, the true-color images on the 15th showed that the ice surface melt pools on the southeast and north sides were darker in color, which indicated that the ice layer was melting deeply and the iceberg structure was more unstable.
The team also found thatThe A23a iceberg was accompanied by significant sea surface ecological changes at the end of its calving period.
Starting from the end of 2025, the A23a broken ice area gradually showed signs of "greening", and the green plume area continued to develop and change.
According to reports, the discoloration of the water surface in polar ice melt areas is inseparable from the outbreak of ocean algae blooms caused by melt water.
True color monitoring map of the two collapses of the A23a iceberg monitored by Fengyun Meteorological Satellite