The Greenland ice sheet is melting faster than forecast

EMBARGOED UNTIL 18.00 GMT WED DEC 5TH *** Exposed cliff of an ice cap in west Greenland. See National story NNmelt Greenland's ice sheet is melting at a scale

Lead by glaciologist and climate scientist Luke Trusel of Rowan University, a team of US and European researchers analyzed more than three centuries of melt patterns in ice cores from western Greenland.

This approach helps researchers update their tracking record, which indicates that ice sheets are melting at a faster pace than previously thought.

"Rather than increasing steadily as climate warms, Greenland will melt increasingly more and more for every degree of warming".

They added that Greenland's dramatic melting was directly linked to the greenhouse gases belched into Earth's atmosphere since the beginning of the industrial revolution. The melting of the ice sheet began to increase during the 19th century, and now it has increased dramatically. "So the ice sheet's response to human-caused warming has been non-linear".

'The melting and sea-level rise we've observed will be dwarfed by what may be expected in the future'.

It seems that icebergs which are calving into the ocean from the edge of glaciers are one component of the water re-entering the ocean and this way rising the sea levels. But more than half of water from the ice sheet that goes into the ocean comes from meltwater runoff, researchers said. In the warmer summer months, melting occurs across much of Greenland's ice sheet surface. At higher elevations, however, the summer meltwater quickly refreezes from contact with the below-freezing snowpack sitting underneath.

Scientists tracking Greenland's ice by satellite and on the ground have seen increasingly dire ice loss. This frozen meltwater creates distinct ice bands that pile up over years to form layers of densely packed ice. Dark bands running horizontally across the cores record the strength of the melting for a given year.

The team analysed these results in combination with the imaging data collected by various satellites and the data from sophisticated climate models, which enabled them to determine the rate of ice melting, not only at core site, but also broadly across Greenland.

Rising seas threaten low-lying cities, islands and industries worldwide.

Today, these rates are "off the charts", said glaciologist Sarah Das, who is a co-author of the study, published this week in the journal Nature. The researchers found that the rate translated to a 50-percent increase in the runoff of meltwater into the sea compared with the preindustrial era.

"From a historical perspective, today's melt rates are off the charts".

"To be able to answer what might happen to Greenland next, we need to understand how Greenland has already responded to climate change", he said.

Das and her colleagues at Rowan University and elsewhere reached that conclusion by examining three ice cores from central west Greenland, and one from an ice cap off the coast, that contain a history of melt events spanning the past 350 years.

"Warming means more today than it did in the past", Trusel said in the statement. Ice core samples were brought back to the labs at the U.S. National Science Foundation Ice Core Facility in Denver, Colorado., WHOI in Woods Hole, Massachusetts, Wheaton College in Norton, Mass, and the Desert Research Institute in Reno, Nevada.



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