Huge iceberg set to break off Antarctica

A view of the rift from the vantage point of NASA’s DC-8 research aircraft. NASA scientist John Sonntag snapped the photos on November 10, 2016, during an Operation IceBridge flight. Image via NASA

A huge iceberg, roughly the size of the U.S. state of Delaware, looks set to break away from the Larsen C ice shelf on the Antarctic Peninsula. Satellite observations from December 2016 show a growing crack in the ice shelf which suggests that the chunk of ice, which has an area of roughly 5,000 square kilometers (about 1,800 square miles) is likely to calve soon. The crack has been growing for years, and British researchers monitoring the crack say that only about 12 miles (19 km) now connect the chunk of ice to the rest of the continent.

A closer view of the crack, taken from NASA’s DC-8 research aircraft. Image via NASA

In a January 6, 2017 statement from the MIDAS Project, which is monitoring changes in the area, Adrian Luckman said:

After a few months of steady, incremental advance since the last event, the rift grew suddenly by a further 18 km (11 miles) during the second half of December 2016.

The crack through Larsen C ice shelf is visible as a dark line from bottom right to top left of this satellite image. Image captured on October 26, 2016. Image via British Antarctic Survey

When it calves, the Larsen C ice shelf will lose more than 10% of its area, which will leave the ice shelf at its most retreated position ever recorded. This event will fundamentally change the landscape of the Antarctic Peninsula. Glaciologist Professor David Vaughan OBE, Director of Science at British Antarctic Survey, said in a statement:

The calving of this large iceberg could be the first step of the collapse of Larsen C ice shelf, which would result in the disintegration of a huge area of ice into a number of icebergs and smaller fragments.

An ice shelf is a floating extension of land-based glaciers which flow into the ocean. Because they already float in the ocean, their melting does not directly contribute to sea-level rise. However, ice shelves act as buttresses holding back glaciers flowing down to the coast.

Larsen A and B ice shelves, which were further north on the Antarctic Peninsula, collapsed in 1995 and 2002, respectively. This resulted in the dramatic acceleration of glaciers behind them, with larger volumes of ice entering the ocean and contributing to sea-level rise. The video below shows footage from the breakup of the Wilkins ice shelf, also on the Antarctic Peninsula, in 2008.

Ice shelves in normal situations produce an iceberg every few decades. According to scientists from British Antarctic Survey, there is not enough information to know whether or not the expected calving on Larsen C is an effect of climate change, although there is good scientific evidence that climate change has caused thinning of the ice shelf.

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Bottom line: A giant iceberg the size of Delaware is set to calve from Antarctica’s Larsen C ice shelf. As of January, 2017, only about 12 miles (19 km) still connect the chunk of ice to the rest of the continent.

Read more from the British Antarctic Survey

January 11, 2017

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