11 March 2016 // Kate Lunau
A gigantic ice shelf is on the verge of splitting away from Antarctica to become a free-floating iceberg, according to newly released images from NASA. They show a massive crack spanning nearly the entire width of the Nansen Ice Shelf—20 miles across and 30 miles long, more than double the size of Manhattan.
The crack was first spotted two years ago via satellite. New images from December show that it has grown quite a bit, now stretching almost the entire width of the ice shelf. NASA scientists Christine Dow and Ryan Walker paid a visit to Nansen in December to take measurements, and flew overhead in a helicopter. “There’s a huge crack, miles long and sometimes over a hundred yards wide,” Walker wrote in a blog post, describing small icebergs tangled up in the crack, producing “a fascinatingly broken icescape.”
Antarctic winter is now setting in, and as of early March, the shelf was still attached. But even in winter, according to NASA, strong winds can keep the surrounding water from locking up into ice, so the shelf could still break away—or hang like a “loose tooth.”
The Nansen Ice Shelf as seen in Dec. 2015. Image: NASA
Scientists in Antarctica and Canada’s North have witnessed ice shelves disintegrating at an unprecedented pace: since 1995, the Larsen Ice Shelf in Antarctica has been rapidly breaking up, losing 75 per cent of its area. Climate change is almost certainly to blame. And while these ice shelf collapses won’t directly contribute to sea level rise—ice shelves are already floating on the surface—they indirectly speed up the process, because ice streams and glaciers behind them are left with a clearer path to fall into the sea.