06 Mar 2014:
Warm River Water Plays Major
Role in Arctic Sea Ice Melt, Study Finds
Relatively warm water flowing into the Arctic Ocean from rivers contributes significantly to Arctic sea ice melt each summer, a phenomenon that will intensify as the region warms, according to NASA researchers
. The river discharge not only melts coastal sea ice, it also has a wider climate impact as it creates more open water, which is darker than ice and absorbs more heat from sunlight. As these NASA images show, when water from Canada's Mackenzie River flowed into the Beaufort Sea in the summer of 2012, average surface temperature of the open water rose by 6.5 degrees C (11.7 degrees F) after the pulse of river water. Flow from the Mackenzie raised sea surface temperatures as far as 350 kilometers (217 miles) from the coast. "These watersheds undergo continental warming in summertime, unleashing an enormous amount of energy into the Arctic Ocean," said an author of the study published in Geophysical Research Letters
. The researchers note that river discharge is becoming an increasingly important contributor to melting Arctic sea ice because the volume and temperature of fresh water discharge is increasing as inland Arctic areas warm more each summer. In the ocean itself, the sea ice is much thinner and more fragmented than in years past, so it is much more vulnerable to pulses of warm water.