Satellite data reveals colossal A23a iceberg’s dimensions and movement patterns.
Scientists now possess precise measurements detailing the immense size of the colossal iceberg A23a. Satellite observations indicate an average thickness of over 280 meters and a total area of 3,900 square kilometers. These statistics yield a volume of roughly 1,100 cubic kilometers and a mass nearing a trillion tonnes. Originating from Antarctica in 1986, the iceberg is on the verge of drifting away from the continent. This critical phase in its movement, expected to unfold in the next few weeks, will determine its trajectory in the Southern Ocean.
To contextualize the newly acquired thickness data, the London skyscraper 22 Bishopsgate stands at 278 meters tall—surpassed in the UK only by the 310-meter Shard tower. However, A23a’s vast area, more than double that of Greater London, renders it proportionally thin, akin to a credit card’s profile. The measurements stem from the European Space Agency’s CryoSat-2 mission, equipped with a radar altimeter capable of gauging an iceberg’s bulk above the waterline and submerged portions.
Dr. Anne Braakmann-Folgmann of the University of Tromsø highlighted that satellites like CryoSat-2 monitor iceberg thickness from space and track its thinning when exposed to warmer ocean waters. A23a emerged from the Filchner Ice Shelf breakout in the southern Weddell Sea, remaining anchored for decades due to sections of varying thickness. CryoSat data revealed a deep keel in a specific section that served as its anchor, resulting in surface crevasses from the collision with the seabed.
The iceberg gradually shed mass over the years, ultimately freeing itself and embarking on movement. Dr. Andy Ridout noted a consistent decrease in thickness over the last decade due to Weddell Sea water temperatures. A23a’s current position near the Antarctic Peninsula raises curiosity about its interaction with surrounding water streams and prevailing westerly winds. Its expected trajectory follows “iceberg alley,” pointing towards the British overseas territory of South Georgia.
The impact of such colossal icebergs on the environment is profound. They stimulate deep seawater mixing, nutrient upwelling, and dust deposition, fostering phytoplankton blooms. Profoundly influencing their surroundings, these icebergs continue to captivate scientific interest.
