It was impossible to see it that day through the thick fog of the Antarctic seas, but Ian Strachan, expedition leader, knew that his ship was approaching an icy behemoth: the largest iceberg in the world was floating somewhere in front of him. “And then the clouds parted and we saw this white, almost abstract line extending along the horizon,” says Ian Strachan, who encountered the iceberg for the first time last Sunday. As his ship moved forward, huge gaping crevices and magnificent blue arcs appeared, carved into the ice wall. Some arches had collapsed under the blows of waves four meters high, he describes.
The tooth-shaped iceberg, named A23a, measures nearly 4,000 square kilometers – or 40 times Paris. Its weight is estimated at nearly a thousand billion tons and its thickness reaches 400 meters in certain places. Heading towards the north of the Southern Ocean, it is currently located between Elephant Island and the South Orkney Islands. Ian Strachan’s private expedition, managed by the company EYOS expeditions, was not the first to witness the spectacle.
“Six hours to overtake him at full steam”
Last December, the British polar research vessel RRS Sir David Attenborough was carrying out a scientific mission to Antarctica when A23a blocked its path. The leader of the expedition, Andrew Meijers, remembers this “magical moment” as he approached the iceberg, the sun appearing, a group of orcas swimming past… “It took us six hours to overtake, at full steam,” says this scientist from the British Antarctic Survey.
The A23a iceberg first broke off the Antarctic coast in 1986, making it both the oldest and largest in the world. But it quickly found itself stuck on ocean shoals, where it stagnated for three decades. In 2020, Andrew Fleming, also of the British Antarctic Survey, saw satellite images suggesting that the giant was “wobbling”. A23a finally broke free late last year, and began venturing north.
The question of a link with climate change – Antarctica’s winter sea ice reached a record low in 2023 – remains open. According to Andrew Meijers, this is like trying to attribute a single fire or flood to global warming. Andrew Fleming nevertheless specifies that the formation of this type of iceberg is a natural process and that each year, one or two immense blocks of ice break away from the white continent. “It is more likely that his time has come” and that he will live out his final months, thinks Andrew Fleming. The “big beast”, as he calls it, moves forward at a walking pace. “The Titanic would have had time to see it coming. »