Researchers studying Antarctic ice shelves have discovered that a massive crack in one of the polar icecaps largest shelves has grown rapidly and may soon lead to the loss of ice larger than the Canadian province of Prince Edward Island.

Between 2011 and 2015 the crack grew by only about 30 kilometres, but since being measured in March of 2016 it had grow an additional 22 kilometres alone. The crack is now 130 kilometers in length and is 350 metres wide.

The Larsen C ice shelf, which the crack is growing across, has ice that is 350 metres thick and is roughly the size of Scotland, making it the fourth largest ice shelf in the Antarctic.

Within the next few years scientists expect the crack to continue to expand, eventually leading to the loss of 6,000 square kilometres of ice, 9-12% of the entire shelf. Once that portion of ice is lost it may lead to the rapid disintegration of the rest of the ice shelf and a rapid increase in glacial melt.

Similar events occurred in 2002 when the Larsen B ice shelf began to collapse, losing about 3,250 square kilometres of ice, and before that the Larsen A shelf collapsed in 1995, losing 1,500 square kilometres of ice.

The losses to both these shelves lead to a 300% acceleration in the melting of the glaciers they held back. In 1996 and 2000 these glaciers were losing 2-4 gigatonnes of ice every year, after the collapse of the shelves this rapidly accelerated to anywhere from 22-44 gigatonnes annually.

The disintegration of these ice shelves was preceded by the occurrences of lakes on their surface caused by warmer than usual surface air temperatures. These lakes act like wedges by draining their water into existing cracks in the ice, deepening and widening them.

These lakes have recently been observed for the first time in the much colder Eastern half of the Antarctic, suggesting that collapses may be coming to the region as well. Melting lakes have also been blamed for the rapid disintegration of the Greenland ice sheet.

Because ice shelves are already floating on top of the water their collapse do not directly lead to raises in global sea levels, however, because they quickly result in the melting of on land glaciers their absence will eventually have consequences.

The discovery of the acceleration in Larsen C’s crack and the formation of pools in the East Antarctic comes alongside a ten month stretch of record setting global temperatures. In the 136 years that temperature records have been kept, each month since last October has set a record high temperature.

 

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