Antarctic: Crack in the ice shelf continues to grow

Only 20 kilometers of ice prevent demolition of gigantic ice sheets

The crack in the Larsen C ice shelf seen from the plane: It is getting wider and growing in length. © NASA / John Sunday
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Impending demolition: The huge rift in the Antarctic Larsen C ice shelf continues to grow. Meanwhile, the crevasse in the fourth largest ice shelf of the earth is 180 kilometers long and has forked at its front. Only about 20 kilometers of ice prevent the gigantic, approximately 5, 000 square kilometers fragment from driving out to the sea. Should this happen, it would be one of the largest Antarctic icebergs ever observed.

The Larsen C ice shelf fills one of the bays on the east coast of the Antarctic Peninsula. The ice layer is 350 meters thick here. Nevertheless, in the year 2015 ice researchers registered first indications of a growing crack in the thick ice shelf. In October 2016, the rapidly increasing crack was already 112 kilometers long and 90 meters wide.

Now Adrian Luckman from Swansea University and his colleagues from the Midas project have re-measured the crack in the Ice Shelf. Because there is currently winter in the Antarctic, this could not be done by plane. Instead, the researchers used radar data from the Sentinel 1 satellites of the European Space Agency ESA.

Growth with two crack tips

The result: The crack has grown further: it is now 180 kilometers long. "This is the first significant change since February of this year, reports Luckman. "Until then, the crack length had remained stable for several months, but the gap has widened steadily - several meters per day."

Length of the crack in the Larsen C ice shelf in May 2017: It is 180 kilometers long and now has a forked peak. © Swansea University / Midas Project

In addition, the crack has now forked and continues to grow at this new junction in the length: "While the previous crack tip has not moved further, a new branch has emerged, " said Luckman. "This is already 15 kilometers long and continues to grow in the direction of the ice front." Only 20 kilometers of ice shelves hold the almost separated piece of ice on the remaining ice shelf. display

Breakage of the ice shelf threatens

Should the approximately 5, 000 square kilometer section of the Larsen C ice shelf break, this would be one of the largest table ice mountains ever observed. "If this iceberg calves, the Larsen C ice shelf will lose more than ten percent of its area, " says Luckman. "This will fundamentally change the landscape of the Antarctic Peninsula. Because never before has the Larsen ice shelf shrunk.

In addition: Should the gigantic piece of ice break off, this could also destabilize the rest of the Larsen ice shelf. The researchers feared that then this ice sheet threatens the same fate as the neighboring Larsen-B: After a similar demolition of a large Tafeleisbergs also broke the rest of the ice shelf and crumbled in the course of less than one month.

(Swansea University, May 3, 2017 - NPO)