Climate Change: Pioneering Radar Technology Discovers Refrozen Water at Base of Greenland Ice Sheet

By Esther Tanquintic-Misa | June 16, 2014 2:31 PM EST       

Ice-penetrating radar technology inserted aboard Nasa survey flights has discovered frozen forms of ice blocks at the very bottom of the Greenland ice sheet which are as tall as city skyscrapers and as wide as the island of Manhattan.

The Thwaites Glacier in Antarctica is seen in this undated NASA image. Vast glaciers in West Antarctica seem to be locked in an irreversible thaw linked to global warming that may push up sea levels for centuries, scientists said on May 12, 2014. Six glaciers including the Thwaites Glacier, eaten away from below by a warming of sea waters around the frozen continent, were flowing fast into the Amundsen Sea, according to the report based partly on satellite radar measurements from 1992 to 2011. REUTERS/NASA/Handout via Reuters


Researchers from Columbia University's Lamont-Doherty Earth Observatory said they saw structures spanning over a tenth of northern Greenland. They were formed when the water at the bottom of the ice sheet melted and subsequently re-froze over hundreds to thousands of years.

"They simply look spectacular," The Guardian quoted Kirsty Tinto, a geophysicist at Lamont-Doherty. "Everything was just flat parallel lines. That is how ice is supposed to be. But here it is breaking all the rules. You get these crazy, folded, distorted, overturned, undulating things at the bottom of the ice, and they are the size of skyscrapers."

But more than the beautiful structures, what's needed to be mostly monitored and studied is what controls the behavior and flow of ice sheets and the glaciers within them as an integral part of improving climate models.

"What this shows is we have to go past just watching the surface," Robin Bell, a climate researcher at Lamont-Doherty, said.

"We see more of these features where the ice sheet starts to go fast," he said. "We think the refreezing process uplifts, distorts and warms the ice above, making it softer and easier to flow."

When the meltwater refreezes, the scientists said the freezing water gives off heat, which softens the surrounding ice and causes the layers of ice to warp to create what Bell calls "tortured ice."

"Overall, these observations suggest that basal freeze-on is a key control on the large-scale flow of Petermann Glacier, a possibility that has not been explored previously," Joseph MacGregor, a University of Texas researcher, wrote in the same report published in the latest issue of Nature Geoscience.

Greenland's glaciers appear to be moving more rapidly toward the sea as climate warms but it remains unclear how the refreeze process will influence this trend, the researchers said.

Petermann Glacier in the north of Greenland made headlines in 2010 when a 100-square mile chunk of ice slipped into the sea.


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