Is Greenland turning into ‘Green’land? NASA study reveals hasty meltdown of Rink Glacier
Source :News Bharati English   Date :29-May-2017

Greenland, May 29: Greenland- an island which lies between the Arctic and Atlantic oceans, covered with ice overall- soon to get ‘Iceless’! Might be in coming days it may become actually the ‘Green’ Land! The study led by three NASA Scientists observed the meltdown of another ice in Rink Glacier of Greenland.

A new NASA study found that during Greenland's hottest summers on record, 2010 and 2012, the ice in Rink Glacier didn't just melt faster than usual, it slid through the glacier's interior in a gigantic wave, like a warmed freezer pop sliding out of its plastic casing. The wave persisted for four months, with ice from upstream continuing to move down to replace the missing mass for at least four more months.

Rink is one of Greenland's major outlets to the ocean, draining about 11 billion tons (Gigatons) of ice per year in the early 2000s roughly the weight of 30,000 Empire State Buildings. In the intensely hot summer of 2012, it lost an additional 6.7 Gigatons of mass in the form of a solitary wave. Previously observed melting processes can't explain that much mass loss. This long pulse of mass loss, called a solitary wave, is a new discovery that may increase the potential for sustained ice loss in Greenland as the climate continues to warm, with implications for the future rate of sea level rise.

The wave moved through the flowing glacier during the months of June through September at a speed of about 4 kilometers a month for the first three months, increasing to 12 kilometers during September. The amount of mass in motion was 1.7 Gigatons, plus or minus about half a Gigaton, per month. Rink Glacier typically flows at a speed of a mile or two a few kilometers a year.

How did the ice melt faster than usual?

The scientists theorize that previously known processes combined to make the mass move so quickly. The huge volume of water lubricated the base of the glacier, allowing it to move more rapidly, and softened the side margins where the flowing glacier meets rock or stationary ice. These changes allowed the ice to slide downstream so fast that ice farther inland couldn’t keep up.

The wave could not have been detected by the usual methods of monitoring Greenland's ice loss, such as measuring the thinning of glaciers with airborne radar. "You could literally be standing there and you would not see any indication of the wave," said JPL scientist Eric Larour. "You would not see cracks or other unique surface features."

“We know for sure that the triggering mechanism was the surface melting of snow and ice, but we do not fully understand the complex array of processes that generate solitary waves,” said JPL scientist Surendra Adhikari, who led the study. "What makes our work exciting is that we are essentially identifying a new, robust observational technique to monitor ice flow processes on seasonal or shorter time scales," Adhikari added.

Earlier the researchers saw the same wave pattern in the GPS data for 2010, the second hottest summer on record in Greenland. Although they did not quantify the exact size and speed of the 2010 wave, the patterns of motion in the GPS data indicate that it must have been smaller than the 2012 wave but similar in speed.