Now-Shrinking Glaciers Could Re-Expand

Article excerpt

Large, marine-calving glaciers have the ability not only to shrink rapidly in response to warming trends, but to grow at a remarkable pace during periods of global cooling, according to geologists working in Greenland.

The conclusion stems from research on Jakobshavn Isbrae--a tongue of ice extending out to sea from Greenland's west coast--published in Quaternary Science Reviews. Through an analysis of adjacent lake sediments and plant fossils, scientists have determined that the glacier, which retreated about 40 kilometers inland between 1850-2010, expanded outward at a similar pace about 200 years ago, during a time of cooler temperatures known as the Little Ice Age.

"Jakobshavn Isbrae has been the focus of intense scientific interest because it is one of the world's fastest flowing glaciers, releasing enormous quantities of Greenland's ice into the ocean," explains geologist Jason Briner. Changes in the rate at which icebergs calve off from the glacier could influence global sea level rise.

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To reconstruct the glacier's advance from east to west during earlier, cooler years, Briner and his colleagues examined sediment samples from Glacial Lake Morten and Iceboom Lake, two glacier-fed bodies of water that sit along the glacier's path of expansion. …