Scientists zero in on causes of glacier acceleration

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Washington, Jan 16 : Analysis of the Kennicott Glacier in Alaska, has led researchers to speculate that it is being accelerated due to internal plumbing issues, therefore also explaining the acceleration of glaciers observed recently on the Greenland ice sheet that are contributing to global sea rise.

The study, carried out by the University of Colorado at Boulder, USA, indicates that meltwater periodically overwhelms the interior drainpipes of Alaska's Kennicott Glacier and causes it to lurch forward.

For the analysis, the team used GPS receivers positioned on the glacier as well as pressure gauges, temperature sensors, sonic distance measuring sensors and electrical conductivity probes.

According to CU-Boulder Professor Robert Anderson of the Institute of Arctic and Alpine Research, the amount of water passing through conduits inside and underneath the Kennicott Glacier increases during seasonal melting and also following annual flooding from a nearby lake.

"The addition of excess water from melting and flooding causes water to back up into a honeycomb of passages inside the glacier, suggesting the resulting increase in water pressure causes the glacier to slide more rapidly down its bedrock valley," he said.

The sliding eventually halts when the moving glacier opens up spaces in its bed that can accommodate some of the excess water, helping to relieve the water pressure, according to the authors of the study.

"In addition, high rates of water flow eventually enlarge the conduits and ducts permeating the glacier, melting them back and allowing more water to bleed from the system, further decreasing the pressure," said Anderson.

According to Anderson, the phenomenon is similar to the plumbing system of a house that is incapable of handling excess water or waste, causing it to back up.

"This is a feedback we are still trying to understand and one that has big implications for understanding the dynamics of glaciers and ice sheets, including the behavior of outlet glaciers on the Greenland ice sheet," he said.

"There are a number of catastrophic draining events of slush ponds on the Greenland ice sheet that may well promote increased sliding of the ice sheet as this water is jammed into a sub-glacial pipe system that is ill-prepared for such inputs," said Anderson.

"This phenomenon is also relevant to small glaciers around the world, because it may help to explain their nonsteady rates of sliding," he added.

ANI

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