Greenland's Draining Lakes Won't Worsen Sea Level Rise?

Just yesterday, Nature World News reported on Greenland's mysteriously vanishing lakes, which can drain entirely in just a matter of a few hours. But now, a subsequent study is saying that while warming temperatures have created more of these supraglacial lakes, they are not likely to worsen Greenland's contribution to sea level rise.

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 to move along this fast conveyor belt," Laura Stevens, a graduate student in MIT's Department of Earth, Atmospheric and Planetary Sciences, said in a statement. "One of the big questions about the Greenland ice sheet is how much of the ice sheet [travels towards the coast] during the summer, and how much is entering into the ocean. Our hypothesis that inland lakes are less likely to drain locally suggests the ice sheet in that region won't speed up. That's good news, at least for the time being."

During the study, researchers at MIT, Woods Hole Oceanographic Institution (WHOI), and elsewhere observed the drainage of North Lake, a 10-meter-deep, 2-kilometer-wide lake on the western side of Greenland. They found that each summer, the lake, like many others, drained quickly, completely emptying in just a couple of hours.