Nature World News: Each summer, Greenland's ice sheet - measuring three times the size of Texas - begins to melt. Pockets of melting ice form hundreds of large, supraglacial lakes on the surface of the ice. Many of these lakes drain through cracks and crevasses in the ice sheet, called moulins, creating a liquid layer over which massive chunks of ice can slide. This natural conveyor belt can speed ice toward the coast, where it eventually falls off into the sea.
"It's essentially a check on the inner ice starting...