Around 80 percent of Greenland is covered by the Greenland Ice Sheet, which Britannica explains is the largest and possibly the only relic of the Pleistocene glaciations in the Northern Hemisphere.

But has it always been so icy?

Well, at the bottom of a 1.4 km core sample, which was taken in 1966 at Camp Century during the Cold War, researchers found well-preserved fossil plants and biomolecules, which means that the massive sheet melted and reformed at least once in the last million years.