Sunday, December 11, 2011

Greenland's Land Mass Rebounding? (PhysOrg)

2010 spike in Greenland ice loss lifted bedrock, GPS reveals

December 9, 2011 by Pam Frost Gorder
2010 spike in Greenland ice loss lifted bedrock, GPS reveals
This is a composite photograph of a GNET GPS unit implanted in the southeastern Greenland bedrock. Credit: Image by Dana Caccamise, courtesy of Ohio State University
( -- An unusually hot melting season in 2010 accelerated ice loss in southern Greenland by 100 billion tons – and large portions of the island's bedrock rose an additional quarter of an inch in response.

That's the finding from a network of nearly 50 GPS stations planted along the Greenland coast to measure the bedrock's natural response to the ever-diminishing weight of ice above it.
Every year as the  Sheet melts, the rocky coast rises, explained Michael Bevis, Ohio Eminent Scholar in Geodynamics and professor in the School of Earth Sciences at Ohio State University. Some GPS stations around Greenland routinely detect uplift of 15 mm (0.59 inches) or more, year after year. But a temperature spike in 2010 lifted the  a detectably higher amount over a short five-month period – as high as 20 mm (0.79 inches) in some locations.
In a presentation Friday at the American Geophysical Union meeting in San Francisco, Bevis described the study's implications for climate change.
"Pulses of extra melting and uplift imply that we'll experience pulses of extra sea level rise," he said. "The process is not really a steady process."
The 2010 Uplift Anomaly (green arrows), superimposed on a map shows the 2010 Melting Day Anomaly (shaded in red). Produced by R. Simmon of the NASA Earth Observatory using data provided by M. Tedesco. Courtesy of Ohio State University
Because the solid earth is elastic, Bevis and his team can use the natural flexure of the Greenland bedrock to measure the weight of the ice sheet, just like the compression of a spring in a bathroom scale measures the weight of the person standing on it.

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