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21 April 2017, 02:57 | Justin Tyler
Meltwater Is Now Streaming Across Antarctica
"I think most polar scientists have considered water moving across the surface of Antarctica to be extremely rare".
Because meltwater streams were thought to be relatively rare in Antarctica before this, they haven't been extensively studied in the past, according to glaciologist Douglas MacAyeal from the University of Chicago, who wasn't involved in the study. "This process might have been responsible for the large-scale break-up of Antarctica's Larsen B Ice Shelf in 2002, when more than 2000 lakes drained in just a few days". The photos exhibited 700 seasonal interconnected ponds, channel and streams.
Scientists had believed that the drainage of meltwater was a rarity in Antarctica.
Bell and colleagues looked at the movement of water on the surface of Nansen Ice Shelf, also part of the Antarctica peninsula, and found that its drainage system may in fact help relieve pressure.
"This is widespread now, and has been going on for decades", said lead author Jonathan Kingslake, a glaciologist at Columbia University's Lamont-Doherty Earth Observatory.
The continent's vast ice sheets contain enough ice to raise global sea levels by almost 200 feet were it all to melt, though even partial melt could cause vulnerable coastal areas that are home to millions to be gradually claimed by the sea.
To piece together a "big picture", Kingslake and his team combed through thousands of photos taken from military aircraft starting in 1947, along with satellite images dating back to 1973.
Scientists think Greenland would provide a clue to know how these streams arise and affect sea level rises.
Most of the melt ponds and streams form near rock outcrops or bluish ice exposed by the sharp winds that scour snow from the surface; these features are darker than the surrounding ice and so absorb more solar energy.
This isn't great news for the stability of the ice shelf.
According to the survey which was documented in two papers published in the journal Nature (one and two), some of the meltwater bodies can grow to gargantuan proportions.
Much of Antarctica's ice is littered with seasonally flowing meltwater streams.
The new research shows that during warm years with considerable melt, a river system forms that eventually ends in a 400-foot-wide waterfall that can siphon off an entire year's worth of surface melt in just a week.
But the main damage to ice shelves comes from ocean water eroding their underbellies. That may make the ice shelf more stable, since the meltwater gets funneled into the ocean immediately instead of building up on top of the ice shelf and cracking the ice below.
Numerous newly mapped channels start in mountains that poke between glaciers, or in areas where winds have whipped the snow covering off bluish ice.
"When you turn up the temperature, it's only going to increase".
They catalogued almost 700 distinct networks of interconnected ponds, channels and streams criss-crossing the continent.
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