KU research uncovers rapid pace of glacier melt

A KU researcher netted international attention last month with a finding that glaciers in Greenland are dissipating at more than twice the rate they did a decade ago.

Researchers Pannir Kanagaratnam of KU's Center for Remote Sensing of Ice Sheets and Eric Rignot of NASA's Jet Propulsion Laboratory in Pasadena, Calif., discovered that the mass loss of ice—through enhanced glacier flow and enhanced runoff—is increasing with time, particularly on the periphery of the glaciers. The deterioration is concentrated along channels occupied by outlet glaciers that discharge into the sea.

"Even within this short time frame, large-scale changes are being observed," Kanagaratnam said.

The researchers used data from Canadian and European satellites and advanced synthetic aperture radar capable of measuring ice thickness developed by professors and graduate students at KU. With these tools they were able to conduct the first known comprehensive survey of glacial ice discharge rates in Greenland over the past decade.

Previous estimates of mass loss from non-surveyed glaciers relied upon models of ice melt that assumed their ice flow rates did not change over time. A 2004 report written by Rignot and involving researchers at KU showed that almost immediately after the 2002 Larsen B ice shelf collapse in Antarctica, glaciers flowed up to eight times faster than they did before the break-up. The speed-up also caused glacier elevations to drop, lowering them by up to 125 feet in six months.

Their data, collected through the satellites and airborne radar supported by NASA, indicate the 21 largest glaciers accelerated 28.5 percent between 1996 and 2000 and 57 percent between 1996 and 2005. The flow acceleration varies substantially from glacier to glacier, they report, but is nonetheless widespread and systematic. The researchers found the ice sheet mass balance declined by roughly 220 cubic kilometers—about 52.7 cubic miles, or one-tenth the size of Mount Everest—in 2005. Its contribution to sea level rise is approximately a half millimeter a year. In 1996, the increase in sea level from Greenland's ice sheets was roughly .2 millimeters.

"We do not know how much of it is due to natural climate change and how much of it is due to human influence," Kanagaratnam said. "But the fact is that temperature is definitely rising, and there is a strong correlation between the temperature rise and sea level rise."

Full text of article at http://www.oread.ku.edu/Oread06/Mar6/glaciers.shtml