The world's largest iceberg is slowly moving away from Antarctic waters. The space agency ESA can calculate the dimensions of the ice colossus from space.
It is about 4,000 square kilometers in size, has an average depth of 280 meters, a volume of 1,100 cubic kilometers and weighs just under a trillion tons: A23 – the largest iceberg in the world. For comparison, Vienna's DC Tower is 220 meters high and the area of Burgenland is 3,962 square kilometers. The ice colossus is currently moving comparatively quickly away from Antarctic waters, satellite images from the European Space Agency Esa show.
The colossus named A23a broke away from the Filchner-Ronne ice shelf in 1986, but remained trapped on the seabed for a long time, according to Esa. It had loosened in 2020, but is only now beginning to gain momentum, driven by winds and currents. And researchers are watching closely to see what direction it will take. Like most icebergs in the so-called Weddell sector, it will likely end up in the South Atlantic.
The European Space Agency calculates the iceberg's dimensions and its trajectory as part of the CryoSat-2 mission. This is a satellite for observing Earth's ice masses, especially those in the Arctic. Using a radar altimeter, the satellite can record how much of the iceberg is above the water's surface. If you use information about ice density, you can calculate how much of the ice mass is underwater.
Satellite image of the A23. Portal / European Union / Copernicus Sentinel-3
A23 has a keel 350 meters long
The BBC reports that it can also be used to determine how much the iceberg is shrinking in warm waters. “Along with knowledge of the topography of the seabed, we know when an iceberg runs aground or when it is thin enough to break loose again,” said expert Anne Braakmann-Folgmann, from the Norwegian University of Tromsø, in an interview with the British broadcaster.
Now, researchers have used data from CryoSat-2 to find out why the iceberg hasn't moved in the last three decades, according to the BBC: It's particularly deep in one place. Like a keel, the ice protrudes almost 350 meters into the depths. The iceberg lost mass and therefore broke free. (ed./ag.)