Climate models will need to incorporate this new twist in Antarctic meltwater, and their predictions should become less dire than they now are. Glaciers are darker as compared to other snow covered ice-sheets and hence absorb more solar radiations. During the summer, which corresponds to the Northern latitude winter, an extensive network of some 700 rivers, channels, and streams pop up.
Scientists have long understood that water from melted ice harm ice sheets by flowing into cracks and refreezing, but that phenomenon was thought to be limited to a small part of the continent. The ice shelves will "still become more unstable as the climate warms", Dr. Banwell says, but they might not break up as rapidly as otherwise thought.
"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.
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. Unfortunately, those drainage systems are still really effective at sloughing off water into the ocean, which will still affect sea level rise.
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. The liquid water flows down through the slope covering the underlying snow. But no one had ever done a systematic survey of Antarctica's meltwater systems.
This isn't great news for the stability of the ice shelf. At least when it comes to breaking up ice sheets.
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. "Ice is dynamic and complex, and we don't have the data yet".
Numerous newly mapped channels start in mountains that poke between glaciers, or in areas where winds have whipped the snow covering off bluish ice.
"It is important to find out how many other ice shelves have a large scale river network, which transports meltwater efficiently into the ocean, as now, we are only aware of the river and waterfall system on the Nansen ice shelf", Alison Banwell, a glaciologist at the Scott Polar Research Institute at the University of Cambridge, said in an email. A better understanding of how, when and where the meltwater forms could help scientists better model how different ice shelves will respond to rising temperatures, which are expected to increase surface melt.
The movement "changes the way we think about the impact of meltwater", Dr. Bell says.