A yellow submarine has helped to solve a puzzle about one of Antarctica's fastest-melting glaciers, adding to concerns about how climate change may push up world sea levels, scientists said Sunday. The robot submarine, deployed under the ice shelf floating on the sea at the end of the Pine Island Glacier, found that the ice was no longer resting on a subsea ridge that had slowed the glacier's slide until the early 1970s. Antarctica is key to predicting the rise in sea levels caused by global warming - it has enough ice to raise sea levels by 57 meters (187 ft) if it ever all melted. Even a tiny thaw at the fringes could swamp coasts from Bangladesh to Florida. Satellite photographs in the early 1970s had shown a bump on the surface of the ice shelf, indicating the subsea ridge. That bump has vanished and the 7-meter (22 feet) submarine found the ridge was now up to 100 meters below the ice shelf.
