Jul 20, 2019 | Updated: 08:51 AM EDT

Once Solid Peninsula in Antarctica Begins to Melt

May 24, 2015 04:35 PM EDT

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Antarctica
(Photo : By Vincent van Zeijst (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons)

A part of Antarctica that scientists once thought to be safe from climate change is now showing signs of instability, and the loss of this ice could lead to the rising sea levels around the world.

For years there was no reason to be alarmed about melting chances of the Southern Antarctic Peninsula.  However, everything seemed to change in 2009.  Beginning in 2009, several glaciers along a wide area of about 750 kilometers or 460 miles in length began to thaw and to pour water into the oceans.  Researchers estimate that about 55 trillion liters of water are being poured into the waters each year.

Researchers were able to discover this loss using data from the European Space Agency's CryoSat-2 satellite, whose sole purpose is to monitor the ice by remote sensing.

"It appears that sometime around 2009, the ice-shelf thinning and the subsurface melting of the glaciers passed a critical threshold that triggered the sudden ice loss," Bert Wouters, who led the study that appeared in Science this week and is with the Bristol Glaciology Centre at the University of Bristol, said.

This makes this area the next largest source of sea level increase in Antarctica.  "To date, the glaciers added roughly 300 cubic km of water to the ocean," Wouters said. "That's the equivalent of the volume of nearly 350,000 Empire State Buildings combined."

The amount of ice that is being lost in this area is so large that it is causing minute shifts in the gravity field of the entire planet.  These shifts have been detected by the Gravity Recovery and Climate Experiment (GRACE) satellite.  

"This is one of now three really quite substantial signals that we've seen from different parts of West Antarctica and the Antarctic peninsula that is all going in the same way," said Jonathan Bamber of the University of Bristol, one of the paper's authors. The other two are the losses of ice in the Larsen ice shelf region where glaciers have sped up their seaward lurches following past ice shelf collapses and in West Antarctica.

To understand the problem, it is important to picture what scientists call the ice shelf's "grounding line."  This is the area where the ice mass intersects with the bedrock below it and also the ocean in front it.  "The geometry of the bedrock ... it's below sea level and it dips inland" in this region, Bamber says. "That geometry means that the grounding line is potentially unstable."

"It only needs to change position slightly for it to move quite rapidly, and for a sustained period, further inland. That's the theory behind the instability of these sectors of West Antarctica and the peninsula."

The greater threat of meltic in the Antarctic region comes from the ice shelves and glaciers in West and East Antarctica, whose potential contribution to rising sea levels could be measured in feet or meters instead of inches or centimeters. Still, the overall picture across the continent is the same and many frozen areas of the region are changing worrying researchers and scientists across the world.

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