Most vulnerable are the massive, floating ice shelves that ring the Antarctic continent and help prevent inland glaciers from sliding toward the sea, they reported in the journal Nature.
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".
Climate models will need to incorporate this new twist in Antarctic meltwater, and their predictions should become less dire than they now are.
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.
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.
Scientists are also studying Greenland for clues as to how these streams might develop and affect sea level rises - between 2011 and 2014, about 70 percent of the 269 billion tons of ice and snow lost by Greenland to the oceans was due to meltwater. "Meltwater is still a bad thing", she says, but it's "not always going to be a death to ice shelves". As the ice melts, liquid water will create a path downhill through overlying snow. Climate change is a real phenomenon, and its link to human activities is at this point well understood, but the details of the system and the ways in which its countless variables interact with one another are much less clear to us. This causes melting of ice. "So we really can't tell what the future holds for any one particular ice shelf".
The different types of meltwater drainage systems could raise different possibilities for ice sheet stability.
A relatively flat ice shelf (a) is likely to have numerous melt ponds and streams, which could destabilize the shelf by infiltrating crevasses and causing more fracture, while an ice shelf with a steeper slope (b) may have more of a large river network that could export meltwater off the ice shelf.
Newly recorded drainages usually start near mountains finding their way down through glaciers.
"He added: "Our study has found that extensive networks of lakes and streams have persisted in Antarctica for decades which move surface water across its ice sheets on" to ice shelves".
"When you turn up the temperature, it's only going to increase". Banwell, who wrote a Nature commentary on the two papers, was not involved with the research. He said it was "a stretch", though to say that surface rivers like that on the Nansen shelf would protect the ice.
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