Greenland is home to the second largest glacier on Earth. The study shows that it shrank considerably a good 400,000 years ago. This shows how sensitive the Greenland Ice Sheet is to heat and what that could mean for sea levels. A good 400,000 years ago, much of Greenland was ice-free and resembled a tundra landscape. This is reported by an international research team after analyzing an ice core from the northwest of the island in the journal Science. According to the scientists, the result shows how sensitive the Greenland Ice Sheet – the second largest mass of ice on Earth – responds to changes in temperature.