Saturday, May 27, 2017

Waves Rippled Through Greenland’s Ice. That’s Ominous

Rink Glacier from 34,000 feet. (Credit: John Sonntag/NASA) Click to Enlarge.
On its surface, the Greenland ice sheet is a vast expanse of seemingly immovable ice.  But beneath the monotonous stretch of white, scientists have discovered evidence of waves rippling through one of its outlet glaciers and roiling its innards.

The waves, observed during the two most intense melt seasons on record, sent an unprecedented cascade of ice and water rushing into the sea and warping the very bedrock upon which the ice sits.  As temperatures continue to rise, scientists fear that massive waves of ice could expedite Greenland’s melt even further, pushing sea levels higher.

It’s the latest piece of bad news about Greenland’s ice.  The ice sheet has been pouring roughly 270 megatons of ice a year into the ocean via the glaciers that stretch out from its hulking mass since 2000.  That’s a big uptick compared to preceding decades.

The new research, published earlier this week in Geophysical Research Letters shows a new way that climate change is taking a toll.  Scientists at the NASA Jet Propulsion Laboratory, led by Surendra Adhikari, were looking at data from a series of GPS stations set up around the various outlet glaciers that tumble from Greenland’s ice sheet to the sea.  Ironically, they were looking at the GPS data to see if it was worth maintaining the network of stations that rings Greenland.

They found evidence of a never-before-observed phenomenon affecting Rink Glacier, a glacier on the western flank of Greenland.  The glacier usually sends about 11 gigatons of ice into the ocean each summer melt season.

But 2012 was different.  A fast-moving (by glacial standards), massive wave rumbled through the glacier’s interior, causing an extra 6.7 gigatons of ice and water to slosh into the sea.  That’s the equivalent of 55 million blue whales, the largest animal on earth.
Greenland’s melt is currently responsible for roughly 25 percent of observed sea level rise. That percentage could increase in the coming years if what happened at Rink Glacier spreads to other glaciers.

Read more at Waves Rippled Through Greenland’s Ice.  That’s Ominous

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