Iceberg weighing at least trillion tonnes breaks off in Antarctica

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larsen c ice shelf

A massive iceberg weighing at least a trillion tonnes and said to be as huge as Delaware has broken off the Larsen C ice shelf in Antarctica.

The iceberg is about 5,800 square kilometres (2,200 square miles) and is holding water in frozen form with a volume twice that of Lake Erie, one of the North American Great Lakes. With the massive iceberg now separated from the ice shelf, the size of the Larsen C shelf has reduced in area by more than 12 per cent. The gargantuan ice cube will probably be named A68.

Separation occurred somewhere between Monday and Wednesday, and was recorded by a NASA satellite. The calving of ice shelves occurs naturally, though global warming is thought to have accelerated the process in some regions. Warmer ocean water erodes the underbelly of the ice shelves, while rising air temperatures weaken them from above.

Icebergs calving from Antarctica are a regular occurrence, and there are thousands of them. The latest behemoth will be closely watched for potential risk to ships. There is also a risk that smaller, loose pieces which stayed behind when the main chunk broke off will now calve away.

The fate of A68 is hard to predict. Drinkwater said it could “hang around” for some time before the tides and wind force it further out to sea. According to an ESA statement, ocean currents could drag the iceberg, or pieces of it, as far north as the Falkland Islands, posing a hazard for ships in the Drake Passage.

Experts disagree over whether the calving heightens the risk of Larsen C disintegrating like its neighbours Larsen B in 2002 and Larsen A in 1995. Floating on the ocean, ice shelves are fed by slow-flowing glaciers from land. Without them, the glaciers would flow directly into the sea. If the glaciers held in check by Larsen C were to spill into the Antarctic Ocean, it would lift the global water mark by about 10 centimetres (four inches), previous research has shown.

With its new shape and size, Larsen C may be less stable, the MIDAS researchers warned.

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