Another Huge Crack Has Appeared on Antarctica's Larsen C Ice Shelf

Larsen C ice shelf
The Larsen C ice shelf in December 2016. NASA/John Sonntag

Another major crack has appeared on the Larsen C ice shelf in Antarctica, satellite images have revealed. The new rift in one of the region's biggest floating platforms of ice branches off from another major fissure, scientists have observed growing fast over the last year. The new crack is just over nine miles long and branches off the original 111 mile-long fissure.

Scientists with Project Midas, a U.K. based Antarctic research group, have been tracking changes to the Larsen C ice shelf for the past two years. In August 2016, when they were able to observe the ice shelf again after the polar night, they discovered the original crack had grown by 13.5 miles.

In January, they announced the rift had grown a further 11 miles. "Only a final 20km [12 miles] of ice now connects an iceberg a quarter of the size of Wales to its parent ice shelf," they said in a statement at the time.

"When it calves, the Larsen C Ice Shelfwill lose more than 10 percent of its area to leave the ice front at its most retreated position ever recorded; this event will fundamentally change the landscape of the Antarctic Peninsula." The iceberg, when it breaks away, will measure 3,100 square miles.

New satellite data has now shown the presence of a new nine mile-long branch along the rift, moving in the same direction as the larger rift.

"While the previous rift tip has not advanced, a new branch of the rift has been initiated. This is approximately 10km [6 miles] behind the previous tip, heading towards the ice-front," Adrian Luckman, head of Project Midas, said in a statement.

The researchers said observing a new rift was the first significant change since February. Luckman said that though the original rift hadn't grown in length for several months, it was growing wider, at a rate of more than three feet per day.

"It is currently winter in Antarctica, therefore direct visual observations are rare and low resolution. Our observations of the rift are based on synthetic aperture radar interferometry from ESA's [European Space Agency] Sentinel-1 satellites. Satellite radar interferometry allows a very precise monitoring of the rift development," he added.

The Larsen C ice shelf is 217 miles thick and sits at the edge of West Antarctica, holding back the flow of glaciers feeding into it. Scientists believe that after the calving event, the ice shelf will follow the same fate as the Larsen A and B ice shelves, slowly disintegrating until nothing is left.

Larsen C ice shelf
Image showing how the Larsen C ice shelf has grown. Project Midas

A similar calving event took place at Larsen B in 2002 and 2003 and the ice shelf has been weakening ever since. In 2015, NASA released footage showing how the ice shelf was in its "final act" and will likely completely disintegrate by the end of the decade.

Discussing Larsen B, Ala Khazendar, from NASA's Jet Propulsion Laboratory, California, said: "Although it's fascinating scientifically to have a front-row seat to watch the ice shelf becoming unstable and breaking up, it's bad news for our planet. This ice shelf has existed for at least 10,000 years, and soon it will be gone."

Current projections indicate that if the Larsen C ice shelf disintegrates, it could raise sea levels by up to 10cm.

Larsen C ice shelf
The Larsen C ice shelf. This image shows the 111-mile rift that grew over two years, before a Delaware-sized iceberg broke away. John Sonntag/NASA