An iceberg labeled A23a has started moving in Antarctica. The route will be closely monitored as it could impact maritime routes or local wildlife.
It is 38 times larger than Paris. The world’s largest iceberg is moving for the first time in more than three decades. It is called A23a, measures almost 4,000 square kilometers and weighs just over a billion tons in the heart of Antarctica, whose melting worries all scientists. It’s rare to see an iceberg of this size in motion, emphasizes Oliver Marsh, a glaciologist with the British Antarctic Survey, so scientists will be watching its trajectory closely.
A23a broke away from the Filchner-Ronne Ice Shelf in West Antarctica in 1986. Since then, its submerged part, the largest among icebergs, has remained stuck at the bottom of the Weddell Sea. It even once housed a Soviet research station. Recent satellite images show it is now drifting quickly past the northern tip of the Antarctic Peninsula, helped by strong winds and currents. “Over time it probably became a little thinner and gained that little extra buoyancy that allowed it to lift off the seafloor and be pushed by the ocean currents,” said Oliver Marsh. A23a is one of the oldest icebergs in the world.
This behemoth is likely to get caught in what scientists call the Antarctic Circumpolar Current. This sends it along a path known as “Iceberg Alley” toward the Southern Ocean, where more of its kind can be found floating in the dark waters. But “an iceberg of this size has the potential to survive in the Southern Ocean for quite a long time, even if it is much warmer, and it could push further north towards South Africa, where it could disrupt shipping,” said Oliver Marsh.
Another possibility is that it will be blocked again, this time on the island of South Georgia. 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 huge iceberg, the A68, sparked fears it could collide with South Georgia, destroying marine life on the seabed and cutting off access to food. Such a catastrophe was ultimately averted when the iceberg broke into smaller pieces – a possible endgame for the A23a too.