Greenland Ice Sheet Flow Driven by Short-Term Weather Extremes, Not Gradual Warming, Research Reveal

ScienceDaily (Dec. 9, 2010) — Sudden changes in the volume of meltwater contribute more to the acceleration -- and eventual loss -- of the Greenland ice sheet than the gradual increase of temperature, according to a University of British Columbia study.

The ice sheet consists of layers of compressed snow and covers roughly 80 per cent of the surface of Greenland. Since the 1990s, it has been documented to be losing approximately 100 billion tonnes of ice per year -- a process that most scientists agree is accelerating, but has been poorly understood. Some of the loss has been attributed to accelerated glacier flow towards ocean outlets.

Now a new study, published in the journal Nature, shows that a steady meltwater supply from gradual warming may in fact slow down glacier flow, while sudden water input could cause glaciers to speed up and spread, resulting in increased melt.

"The conventional view has been that meltwater permeates the ice from the surface and pools under the base of the ice sheet," says Christian Schoof, an assistant professor at UBC's Department of Earth and Ocean Sciences and the study's author. "This water then serves as a lubricant between the glacier and the earth underneath it, allowing the glacier to shift to lower, warmer altitudes where more melt would occur."

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but GW has nothing to do with the increased flow of the Greenland Ice Sheets.