http://www.digitaljournal.com/news/environment/greenland-s-rink-glacier-exhibiting-ominous-new-type-of-ice-loss/article/493702

Greenland's Rink Glacier exhibiting ominous new type of ice loss

Posted May 27, 2017 by Karen Graham
While climate scientists have been watching the effects of climate change on Earth's glaciers and ice shelves, something much more ominous and worrisome has been happening to one of Greenland's outlet glacier's that holds back literally megatons of ice.
Rink Glacier in western Greenland  with a meltwater lake visible center. The gigantic solitary wave ...
Rink Glacier in western Greenland, with a meltwater lake visible center. The gigantic solitary wave dented the bedrock underneath the ice sheet.
NASA/JPL
The Antarctica Peninsula's greening and the anticipation of a large iceberg breaking off from the Larsen C ice shelf is small potatoes to a new type of ice loss National Aeronautics and Space Administration scientists have discovered in Greenland.
The strange and very unusual loss of ice is called a "solitary wave," and it happened in 2012, but there's more to the story. Keep in mind that to look at the Greenland ice sheet, all someone sees is miles and miles of barren whiteness, seemingly solid and motionless.
But that's what is so strange and worrisome. It is not a motionless field of ice at all. In a new study, scientists have discovered evidence of waves rippling through Greenland's Rink Glacier, an outlet glacier to the sea on the island's west coast. Not only that, but the rippling waves have been so strong they reshaped the bedrock upon which the ice sheet sits.
Rink Glacier from 34 000 feet.
Rink Glacier from 34,000 feet.
John Sonntag-NASA/JPL
Three scientists from NASA's Jet Propulsion Laboratory in Pasadena, California, led by Surendra Adhikari are responsible for the new study, the first of its kind that precisely tracks a glacier's loss of mass from melting ice using the horizontal motion of a GPS sensor. The research was published in the online journal Geophysical Research Letters on May 26, 2017.
First evidence of the solitary waves
According to NASA scientists, Greenland has been losing about 11 billion tons of ice each year since the early 2000s. But it was noticed that in 2012, during a particularly intense melting season, the Rink Glacier lost an additional 6.7 gigatons of ice. What was so alarming was that the intensity of the ice loss caused by the strange wave altered the bedrock under the ice sheet.
The scientists measured the speed of the wave, and when it was triggered in June 2012 and as it proceeded through August that year, it traveled at a rate of 2.5 miles (4 kilometers) per month, then accelerated to 7.5 miles (12 kilometers) a month in September. It continued to move for the next four months until it reached the sea.
From October through January the glacier gained mass as ice continued to move downstream to replace the lost mass. "This systematic transport of ice in fall to midwinter had not been previously recognized," Adhikari emphasized.
This image taken by NASA s Operation IceBridge in Greenland shows the broad seemingly endless expans...
This image taken by NASA's Operation IceBridge in Greenland shows the broad seemingly endless expanse of the ice sheet.
NASA/Operation Ice Bridge
But here's the thing - No one saw it because it was all happening underneath the ice. "You could literally be standing there and you would not see any indication of the wave. You would not see cracks or other unique surface features," JPL scientist and study co-author Eric Larour said.
A somewhat similar wave was picked up by GPS sensors as it passed under the ice sheet in 2010, although it wasn't nearly as extreme as the one in 2012. What is even more interesting is that scientists had been thinking of removing all the GPS stations around Greenland at the time, believing there was no need for them.
Understanding what is happening and what it means for the future
Scientist note that the meltdown of the ice sheet in 2012 was extreme, possibly being aided by soot from Siberian wildfires that coated the ice fields and resulting in 95 percent of the ice sheet going into meltdown.
They also suspect that the increased meltwater in the interior of the of the ice sheet created new pathways for the flow of water and likely lubricated the base of the glacier where it adjoins the bedrock, priming it for the massive shudder when the ice moved through it.
Radar image of Rinks Isbrae glacier  on the western coast of Greenland  acquired on 16 February 2006...
Radar image of Rinks Isbrae glacier, on the western coast of Greenland, acquired on 16 February 2006 by Envisat's Advanced Synthetic Aperture Radar (ASAR).
European Space Agency
Ice researcher Robin Bell, with the Lamont-Doherty Earth Observatory, calls the research a “beautiful study linking how the surface of the ice sheet melts and slides with how the surrounding mountains (solid earth) responds. (It’s) remarkable to see the earth lurch in a year when the ice changes more.”
The researchers point out that temperatures are likely to keep rising due to climate change and melt seasons like the one we saw in 2012 will one day become the norm. This means we will be seeing more of these strange glacial waves.
"We suspect that solitary waves may be unique to high melt years,” Adhikari said. “The more warming, the more surface meltwater available to trigger ‘extraordinarily’ dynamic behavior of glacier such as the one we discovered in Rink Glacier.”