A one trillion tonne iceberg has broken off from an Antarctic ice shelf, changing the shape of the Antarctic Peninsula.

The much-anticipated calving from the Larsen C Ice Shelf reduces its area by more than 12 per cent, though the 5800 square kilometre iceberg won't have an impact on sea levels as it was already floating before breaking away completely.

But it will require the map of the Antarctic to be redrawn.

Researchers have previously shown the rift could increase the risk of instability of the wider ice shelf, leading to its collapse - a fate that befell its neighbour Larsen A, seven years after it experienced its own calving event in 1995.