Greenland GPS

Each spring, the melting ice sheet forms large lakes. A decade ago, scientists discovered that cracks can form suddenly in the bottom of these lakes and drain them within hours. To learn how this phenomenon happens, a research team led by Sarah Das (left) and Mark Behn at WHOI and Ian Joughin at the University of Washington (center), along with UW graduate student Josh Carmichael (right), installed a network of GPS units to record the movements of the ice before, during, and after a sudden drainage event. Their study, published in June 2015, discovered a surprising trigger mechanism. (Photo by Laura Stevens, Woods Hole Oceanographic Institution)