The world’s biggest iceberg is on the move for the first time after being stuck to the ocean floor for 30 years. The iceberg, called A23a, is 3884 km sq in size, which is twice the size of London. It is also 399m thick, which is about two-thirds as high as the world’s tallest building, the Burj Khalifa in Dubai.
The iceberg split from the Antarctic coastline in 1986 but got stuck to the ocean floor and became an ice island. It started drifting (漂流) again in 2020 but picked up speed this year as wind and currents pushed it along faster. The iceberg has started heading past the northern tip of the Antarctic Peninsula (南极半岛) and could soon leave Antarctic waters altogether. The iceberg will most likely end up in the Antarctic “Circumpolar Current” before being pushed into a path known as “iceberg alley”.
Icebergs like A23a that end up in the Weddell sector usually follow the same path because of the movements of the Circumpolar Current, which is the strongest current in the Earth’s oceans. From there, the huge iceberg might drift towards South Georgia island, which often has big tabular (板状) icebergs sitting off its coast. The ice blocks usually get attached to the shallow continental shelf of the island, which is considered British territory.
If A23a gets stuck near South Georgia, it might pose a problem for the millions of seals, penguins and other seabirds that live on the island. The mega berg could get in the way of the animals’ normal routes of searching for food, stopping them from feeding their young properly.
But all icebergs eventually melt and disappear, releasing mineral dust. And this dust is an important part of oceanic food chains. “In many ways these icebergs are life-giving; they are the origin point for a lot of biological activity,” said Dr Catherine Walker. The scientists will observe the movement of A23a closely.
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