Paris (AFP) – Antarctic ice-sheets risk breaking into the sea faster than previously thought in stretches of up to 600 metres a day, speeding up the rise in sea levels, new research indicates. In a paper published Wednesday in science journal Nature, researchers studied traces left by retreating ice-shelves thousands of years ago on the seabed off Norway. Global warming due to human-caused carbon emissions is reducing ice, raising warnings that dangerous "tipping points" could be reached, with sudden major melting driving sharp rises in sea level. "Our study shows that pulses of extremely rapid ice-sheet retreat could occur across...