Massive Antarctic Larsen C crack extends by nearly 10km

An enormous crack in an Antarctic ice shelf is continuing to grow, extending by nearly 10km since the beginning of the year.

The spectacular rift in the Larsen C ice shelf, located on the Antarctic Peninsula, is now more than 175km long.

Just 20km of ice remains connecting the shelf together. If the rift fully extends, the resulting iceberg would be around twice the size of Samoa - 5000 square kilometres, one of the biggest on record.

"When it calves… this event will fundamentally change the landscape of the Antarctic Peninsula," the British Antarctic Survey (BAS) said in a blog post as part of Project MIDAS, which is monitoring the rift.

The crack had another sudden jump in growth at the end of December, growing 18km in just over two weeks.

Its latest growth grew parallel to the shelf edge, meaning the same amount of ice is connecting it together, but also the resulting iceberg will be larger than previously thought.

Larsen C ice shelf crack (Project MIDAS / British Antarctic Survey)
(Project MIDAS / British Antarctic Survey)

The Larsen C ice shelf floats on the water, so an iceberg breaking off would have minimal effect on sea level rise.

But there are fears the massive iceberg would leave the remaining ice shelf less stable than it was.

"We have previously shown that… Larsen C may eventually follow the example of its neighbour Larsen B, which disintegrated in 2002 following a similar rift-induced calving event," BAS said.

The ice shelf helps hold back some of the West Antarctic ice sheet from sliding into the ocean, which would have a devastating effect on sea levels.