Environmental News Network: As the Arctic warms, Greenlands fringe of glaciers is thinning and meltingbut the future of the Greenland ice sheet remains a giant question mark. Until recently, that was also true of the ice sheets past: Scientists have long debated whether it might have shrunk away to nothing during Earths warmest periods. Now, a new study suggests that Greenland was entirely ice free at some point in the last 1.25 million years. We should be worried about the Greenland Ice Sheet, says Joerg Schaefer, a...