June 2, 2017

One of the biggest icebergs ever is about to break off of Antarctica

In a week of bad news for climate change action, bad news from Antarctica has followed.

The enormous crack on the Larsen C Ice Shelf has taken a sudden change of direction, meaning the creation of one of the biggest ever bergs could happen sooner than expected.

Activity between 25 May and 31 May, measured by the European Union's Sentinel-1 satellite, meant the fissure is now just 13km (8 miles) from the edge of the ice.

"The rift has propagated a further 16km, with a significant apparent right turn towards the end, moving the tip 13km from the ice edge," said Prof Adrian Luckman from Swansea University in Wales.

The crack is now around 200km (124 miles) in total length.

The recent spurt followed a period of the crack being stationary during which it entered a region of soft, flexible ice known as a "suture" zone. However, May saw renewed activity resulting in the sharp turn towards the ocean.

Part of a highly troubling pattern

If and when a berg is carved, the likelihood is that it will drift away from the ice shelf quite slowly.

"It's unlikely to be fast because the Weddell Sea is full of sea-ice, but it'll certainly be faster than the last few months of gradual parting. It will depend on the currents and winds," explained Prof Luckman.

However, once scientists declare the berg to have separated, the Larsen C shelf will be assessed to have lost 10 percent of its area, making it much less stable.

Researchers are concerned that the result will mimic those previously seen on ice shelves Larsen A and Larsen B, where carving events led slowly to them breaking up completely.

Although it would take years, a collapse of Larsen C would be a continuation of a pattern seen across the Antarctic Peninsula.
There are a dozen other major ice shelves that have in recent decades either collapsed, retreated or shrunk significantly.
Prof Luckman is working on the MIDAS Project, a UK-based Antarctic research project investigating the effects of a warming climate on the Larsen C ice shelf.

Image credit: John Sonntag/IceBridge/NASA Goddard Space Flight Center