Oceans Take Heat to Glaciers
Greenland's ice sheet has lost mass at an accelerated rate over the last decade, dumping more ice and fresh water into the ocean. Between 2001 and 2005, Helheim Glacier, a large glacier on Greenland’s southeast coast, retreated 5 miles (8 kilometres) and its flow speed nearly doubled.
The team returned to Greenland in March 2010, to do the first-ever winter survey of the fjord. Using a tiny boat and a helicopter, Straneo and her colleague, Kjetil Våge of University of Bergen, Norway, were able to launch probes closer to the glacier than ever before, about 2.5 miles away from the glacier’s edge. Coupled with data from August 2009, details began to emerge of a complicated interaction between glacier ice, freshwater runoff and warm, salty ocean waters.
The fjords contain cold, fresh Arctic water on top and warm, salty waters from the Gulf Stream at the bottom. Melted waters do rise somewhat, but not all the way to the top.
The glacier develops a floating ice tongue, a shelf of ice that extends from the main body of the glacier out onto the waters of the fjord. The shape of the ice tongue influences the stability of the glacier and how quickly it flows. Vigorous currents within the fjord driven by winds and tides also play a part in melting and flow speed.
The March 2010 trip marked the first time the researchers were able to observe winter-time conditions in the fjord, which is how the system probably works nine months out of the year.
Co-authors of the work include Ruth Curry and Claudia Cenedese of WHOI, David Sutherland of University of Washington, Gordon Hamilton of University of Maine, Leigh Stearns of University of Kansas, and Kjetil Våge of University of Bergen, Norway.
