Greenland ice completely melted 7,000 years ago and could happen again

Scientists drilling deep beneath Greenlands ice have uncovered a startling clue about its past-and future. Evidence shows that the Prudhoe Dome, a major high point of the ice sheet, completely melted around 7,000 years ago during a relatively mild natural warming period. That means this supposedly stable ice cap is far more fragile than once thought, raising concerns that todays human-driven warming could trigger similar or even faster ice loss.