Named A23a, a billion-ton iceberg has started moving into Antarctica. Its route will be closely monitored because it could interfere with maritime routes or local wildlife.
It’s 38 times bigger than Paris. The world’s largest iceberg is on the move for the first time in more than three decades. Called A23a, it measures nearly 4,000 square kilometers and weighs a good billion tonnes in the heart of Antarctica, the melting of which worries all scientists. It is rare to see an iceberg of this size in motion, underlines Oliver Marsh, glaciologist at the British Antarctic Survey, so scientists will closely monitor its trajectory.
A23a broke away from West Antarctica’s Filchner-Ronne Ice Shelf in 1986. Since then, its submerged portion, the largest among the icebergs, has remained stuck at the bottom of the Weddell Sea and stay still. There was even once a Soviet research station. Recent satellite images reveal that it is now drifting rapidly past the northern tip of the Antarctic Peninsula, aided by strong winds and currents. “Over time, it probably thinned out slightly and gained that little bit of extra buoyancy that allowed it to lift off the ocean floor and be pushed around by ocean currents. », argued Oliver Marsh. A23a is one of the oldest icebergs in the world.
This giant will likely get caught in what scientists call the Antarctic Circumpolar Current. This will direct it towards the Southern Ocean on a path known as “iceberg alley”, where more of its type can be found floating in the dark waters. But “An iceberg of this size has the potential to survive for quite a long time in the Southern Ocean, even if it is much warmer, and it could head further north towards South Africa where it could disrupt shipping. »said Olivier Marsh.
Another possibility is that it is stranded again, this time on South Georgia Island. This would pose a problem for Antarctic wildlife. Millions of seals, penguins and seabirds breed on the island and feed in the surrounding waters. The A23a could cut off this access.
In 2020, another giant iceberg, the A68, sparked fears it could collide with South Georgia, crushing seabed marine life and cutting off access to food. Such a catastrophe was ultimately averted when the iceberg broke into smaller pieces – a possible end also for the A23a.