Using ice-penetrating radar instruments flown on aircraft, U.S. and British researchers have discovered a previously unknown sub-glacial basin nearly the size of New Jersey beneath the ice sheet near the Weddell Sea.
The ice over the basin may be at a tipping point close to collapse, study co-author Don Blankenship from the University of Texas said.
"If we were to invent a set of conditions conducive to retreat of the West Antarctic Ice Sheet, this would be it," he said.
"With its smooth bed that slopes steeply toward the interior, we could find no other region in West Antarctica more poised for change than this newly discovered basin at the head of the Filchner-Ronne Ice Shelf."
The basin covers 7,700 square miles and is well below sea level, nearly 1.2 miles deep in places, researchers said.
"This is a significant discovery in a region of Antarctica that at present we know little about," Martin Siegert of the University of Edinburgh, who led the project, said.
"The area is on the brink of change, but it is impossible to predict what the impact of this change might be without further work enabling better understanding of how the West Antarctic Ice Sheet behaves."