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"Stable" Antarctic Permafrost Melting Faster than Expected, Researchers Say

Jul 24, 2013 08:31 AM EDT

The stable ice on Antarctic- the coastal permafrost- is melting faster than expected, a new study reported. Researchers said that the melting rate of the coastal Antarctic permafrost is now similar to the melt rate of permafrost at Arctic.

The permafrost in Antarctic was considered to be in equilibrium, meaning that it did melt and refreeze, but its mass remained the same. The regions experienced a cooling trend in the past decade and now have stable temperatures.

However, researchers have observed that the ice in this region is thinning, just like the ice in the coastal Arctic and Tibetan region.

The study was conducted by researchers from The University of Texas at Austin who found that the melt rate in the permafrost at Garwood Valley in the McMurdo Dry Valleys region of Antarctica has increased from 2001 to 2012. The melt rate is now ten times higher than the average melt rate for the present geological epoch.

The McMurdo Dry Valleys are a series of valleys that are devoid of snow. Its landscape includes glaciers, permafrost, frozen lakes and patterned soils. This region contains some of the largest stretches of the ground ice in Antarctica.

"The big tell here is that the ice is vanishing - it's melting faster each time we measure. This is a dramatic shift from recent history," Joseph Levy, a research associate at The University of Texas at Austin's Institute for Geophysics. Levy also said that they have found no evidence that this kind of retreat ever happened in the past.

For the study, levy and colleagues monitored the valley and used time-lapse photography along with weather station data to create a detailed view of how the ground ice is retreating in the region.

Rise in temperatures aren't the major cause for the increased melt rate of ground ice, according to researchers. The melting is largely due to the increased amount of Sun's rays that's hitting the region. The increased radiation is due to changes in weather patterns, they said.

Snow reflects most of sunlight, but not dark ground. Increased amount of sunlight in the region has led to the ground heating up and "cooking" nearby glaciers. The melting of ground ice leads to another phenomenon called "retrogressive thaw slumps." Ground ice loss causes the landscape to sink which leads to creation of slumps. Previous research has shown that regions of Arctic are experiencing these slumps. This is the first time that researchers have been able to document these slumps in Antarctica.

Ground ice doesn't hold much water, but its melting could accelerate the melting of other glaciers in the region. Changes in climate could lead to increase in these slumps along the Antarctic coastline.

"There's a lot of buried ice in these low-elevation coastal regions, and it is primed to melt," Levy added.

The study is published in the journal Scientific Reports.

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