GREENLAND ICE SHEET, GREENLAND
July 18, 2006
A meltwater lake on the surface of the Greenland Ice Sheet 60 miles southeast of Ilulissat. The dark material etching out the crevasses is a combination of natural dust particles kicked up by winds from soils around the Northern Hemisphere; air pollution particulates generated by hydrocarbon burning globally; and the constant rain of meteorite debris that showers the earth. Meltwater produced by spring and summer warming collects in lakes such as these, then flows into moulins, stream channels that drill their way down through the ice. The water then flows out the base of the glacier and into the ocean. The more water there is, the more it lubricates the glacier bed and the faster the ice flows into the sea. Global warming has caused melting many dozens of miles further inland and many hundreds of feet higher than just a quarter century ago. At Swiss Camp on the Greenland Ice Sheet, springtime temperatures have increased 5.4 deg. F (3 deg. C) and winter temperatures 9 deg. F (5 deg. C) since measurements began in 1993. As a consequence, while twenty-two cubic miles of Greenland ice melted in 1996, 54 cubic miles melted in 2005. Current Intergovernmental Panel on Climate Change (IPCC) estimates of global sea level rise--1/8 inch per year--include only water produced by atmospheric warming and not by increased glacier instability from meltwater. The estimate therefore UNDERSTATES sea level rise to be anticipated if the atmosphere continues heating up (the next IPCC report in 2009 will almost certainly adjust its estimates to account for this crucial factor).
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