New Survey Finds Meltwater Is Flowing Across Antarctica

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Scientists have always known that the Antarctic Western Peninsula is melting at an alarmingly high rate but they didn't expect the whole continent to be awash with meltwater during the ephemeral summer.

This meltwater usually refreezes in winter, and it's thought this process isn't contributing much to Antarctica's ice loss just yet. The study, the first to extensively map meltwater, found 700 seasonal systems of ponds, channels, streams.

"This study tells us that there is already a lot more melting going on than we thought", said Robin Bell, a polar scientists at the same institute and lead author of a second study, also published in Nature, on Antarctic melt-water.

"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.

Dr Jeremy Ely, from Sheffield University's geography department, said: "If melted completely, Antarctica's ice sheets contain enough water to raise global sea levels by around 58 metres".

Scientists think Greenland would provide a clue to know how these streams arise and affect sea level rises.

Most of the work to understand the melt of Antarctica's ice shelves and glaciers has concentrated on the effects of warm ocean waters lapping away at them from below, not the surface meltwater produced by warming air temperatures.

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The survey also showed that numerous meltwater streams and channels begin near mountains poking through glaciers or in areas with little or no snow, exposing the underlying bluish ice.

For the study, the researchers systematically cataloged images of surface water taken from military aircraft since 1947 and satellite imagery conducted from 1973 onwards.

Melt-water pooling on the surface of ice shelves can suddenly drain below the surface, fracturing the ice with heat and pressure, studies have shown. Once this happens, a feedback loop is triggered where the melting ice starts exposing more dark ice as the water flows through the snow.

The different types of meltwater drainage systems could raise different possibilities for ice sheet stability.

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. In the face of this almost incomprehensible complexity, we ought to be humble about our current scientific understanding, and acknowledgement that climate research is-like any scientific endeavor-still very much a work in progress. The pace of the damage will increase as temperatures continue to rise as a result of man-made global warming.

The movement "changes the way we think about the impact of meltwater", Dr. Bell says.

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