Crack in one of the largest Antarctic glacier

Pine Island Glacier could lose an iceberg of the size of Dortmund

Crack in the ice: A similar crack as this one from October 2011 gapes again in the shelf of the Pine Island Glacier. © NASA Ice Bridge
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Break in the ice: The Pine Island Glacier in the West Antarctic is about to break off a huge iceberg. Satellite imagery shows a big crack, which already runs through three quarters of the glacier tongue. If the 30-kilometer break continues, an iceberg 300 square kilometers in size could break off the glacier. With that, the ice front of the fastest-flowing Antarctic glacier would retreat another six kilometers.

The 250-kilometer Pine Island Glacier is one of the largest and fastest ice streams in the Antarctic. Its catchment area comprises ten percent of the West Antarctic ice sheet. But just this glacier is one of the ice streams that thaw more and more - maybe its melt is even irreversible, as researchers reported a few years ago. Over the last few years, ice shelves stretching from the glacier into the Amundsen Sea have repeatedly calved huge icebergs, most recently in 2017.

30 kilometers long crack

Now, apparently, a new iceberg demolition is on, as Stef Lhermitte, a geologist at the University of Delft, reported on Twitter (@StefLhermitte). In satellite images of the Pine Island glacier, he has discovered a few days ago already about 30 kilometers long crack in the glacier tongue. "This indicates the imminent calving of an approximately 300 square kilometer iceberg, " says the researcher. This iceberg would be even bigger than last year.

The new crack (blue) and the demolition edge of the iceberg of 2017 on the Pine Island Glacier © Stef Lhermitte / Delft University of Technology based on Landsat images

Until the complete separation of this piece only ten kilometers are missing. "If this break continues, the ice front of the glacier could shift back another five to six kilometers, " says Lhermitte. "The iceberg demolition could be the sixth major calving of this glacier since 2001 after B-44 last year." When this happens, it is still uncertain, but Lhermitte estimates that it will be in a few weeks to months.

Thawed from below

The crack in the glacier has its origin in the middle of the ice shelf, there, as the floating glacier tongue comes into contact with the warmer waters of the Sûdolar Sea. Already in the last year ice researchers had determined that deep trenches at the bottom of the Amundsen lake direct the sea water far under the ice cover and drive like a Fu bodenheizung the glacier melt. display

Just recently, glaciologists have determined that ice loss in the Amundsen Sea has almost tripled since the 1990s. Particularly affected are the Pine Island Glacier and the neighboring Thwaites Glacier. Although it is normal for glaciers to calve icebergs. But these ice streams have been causing the loss of large ice sheets in recent years.

(Stef Lhermitte, NASA, 10/10/2018 - NPO)