Under Greenland's frozen surface is a vast network of channels, crevasses, and basins—its "glacial plumbing system." A few years ago, the water suddenly disappeared from a subglacial lake, which then collapsed into a funny silhouette that NASA likens to a "mitten", but I think looks more like a waving Yeti.
The subglacial lake, a pool of water beneath the ice, drained out into a nearby fjord sometime between mid-August and September of 2011. The speed at which it emptied stunned glaciologists. They recently published a paper in Nature describing the lake. According to NASA's Earth Observatory:
Water rushed from the lake at a rate of about 215 cubic metres per second and caused the ice surface to collapse, forming a 70-metre-deep basin. "This drainage event is perhaps the first recorded instance of a rapid drainage of a subglacial lake in Greenland," said NASA glaciologist Kelly Brunt.
The lake is now slowly refilling again, and this time, the warmer temperatures from climate change may have something to do with it.
Read more about the subglacial lake at NASA Earth Observatory.
Top image: NASA Earth Observatory image by Jesse Allen and Robert Simmon, using Landsat data from the U.S. Geological Survey and acquired by special request with the support of Theresa Arvidson (NASA/GSFC) and Eugene Fosnight (USGS/EDC).