Saturday, July 21, 2007

Small Ice Sources Pose Big Threat to Rising Seas

Andrea Thompson LiveScience Staff Writer

Apparently, “don’t sweat the small stuff” doesn’t apply to sea-level rise due to global warming: Scientists have found that smaller glaciers and ice caps, not Earth's expansive polar ice sheets, could cause the majority of the rise due to melting by 2100.

As snow accumulates on the upper portions of a glacier, the ice thickens and begins to flow down. The rate of flow partly determines how fast the glacier melts.

With rising temperatures, the surface of the glacier melts faster, and the water created percolates down through the ice, making the bed of the glacier more slippery and causing the ice to flow faster.

"Faster flow means more ice discharged to the ocean, which will then melt," Meier explained.

Glaciers high in mountain ranges such as the Alps also melt by flowing in this way, and their melt water runs into rivers and eventually into the ocean.

IPCC's missing info

Meier and his colleagues emphasized these types of losses in their study, detailed in the July 19 online issue of the journal Science, because considerations of flow rates were largely absent from the Intergovernmental Panel on Climate Change's (IPCC) estimates.

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