Zachariae Isstrom glacier. Satellite image showing the size of the Zachariae Isstrom glacier, Greenland, in 2015. This glacier is one of a number in Greenland to undergo rapid changes due to global warming. Research published in 2015 showed that it broke loose from a stable position in 2012 and entered a phase of accelerated retreat. Zachariae Isstrom drains ice from an area of 91,780 square kilometres, about 5 percent of the Greenland ice sheet. It holds enough ice to raise global sea levels by more than 46 centimetres if it were to melt completely. As of 2015, the glacier is losing 5 billion tons of ice every year. Imaged by the Operational Land Imager (OLI) on NASA's Landsat 7 satellite, on 7th August 2015.