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Ocean may Play Bigger Role in Greenland Glacier Melt

Jun 24, 2014 02:35 PM EDT
Greenland Glacier
Scientists have long been concerned that global warming may push the Earth's climate system past a "tipping point," and a new study from Oregon State University (OSU) may have finally identified that threshold.
(Photo : Christine Zenino (Wiki CC0))

Though many recent media reports note that the Earth's warming climate is to blame for Greenland's glacier melt - in addition to other melting ice forms like those in Antarctica - a new study shows that oceans may contribute in large part to these glaciers' demise.

The fate of the Greenland Ice Sheet, a 1.7 million-square-kilometer, 2-mile thick layer of ice that covers Greenland, seems to be in the hands of global warming. Over the last 40 years, its ice-loss has increased four-fold, contributing to one-quarter of global sea level rise.

A recent Nature World News article described scientists' discovery of a mysterious frozen underworld beneath Greenland, comprised of jagged blocks of ice as tall as skyscrapers and as wide as the city of Manhattan. It is now known that these formations, due to their melting and refreezing process, are contributing to increasing ice flows from the glacier.

The current study published today in the journal Nature Geosciences describes how that icy underworld is just the beginning of Greenland's problems.

"Over the past few decades, many glaciers that drain the Greenland Ice Sheet have accelerated, thinned and retreated," study lead author Rebecca Jackson, a Woods Hole Oceanographic Institution (WHOI) graduate student, said in a university news release.

"Scientists have noticed a link between glacier behavior and warming waters off the coast of Greenland, but we have very few direct measurements of ocean waters near the glaciers or at what time scales they vary, which are needed to understand what's happening there."

This research sheds light on the connection between warming ocean waters and glacier ice melt, and provides important data for future estimates of how fast the ice sheet will melt and how much mass will be lost.

Currently, scientists contribute a large part of accelerated ice loss to "submarine melting," a process that involves warmer ocean waters melting on the underside of the ice, where the glaciers extend into the ocean.

The ocean's role in driving ice loss largely remains a mystery, but measurements taken between 2009 and 2013 by Jackson and fellow researchers may be unraveling its secrets.

They looked at temperature, salinity and ocean currents at various water depths - the first data to provide information about the conditions of two fjords, where the third and fifth largest outlet glaciers of the Greenland Ice Sheet end, from fall through the spring.

The scientists suspect the melt rate of the glacier varies with the temperature of nearby water.

"These observations of ocean conditions near outlet glaciers are one step towards a better understanding of submarine melting and the impact of the ocean on the Greenland Ice Sheet," Jackson said.

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