Published: Fri, December 07, 2018
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Greenland Ice Melt Has 'Gone Into Overdrive,' Says Scientists

Greenland Ice Melt Has 'Gone Into Overdrive,' Says Scientists

Today, the ice is melting 50 percent faster than it did before industrialisation and 33 percent faster than during the 20th century.

In July 2012 a series of warm weather engendered nearly the whole surface of the Greenland ice sheet to commence melting a phenomenon with no pattern in the satellite record.

A United Nations report in October said that marine ice sheet instability in Antarctica and/or the irreversible loss of the Greenland ice sheet could result in a multi-metre rise in the sea level over hundreds to thousands of years.

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

The increased melting began around the same time humans started altering the atmosphere in the mid-1800s, said Trusel, lead author of a study of the meltwater runoff that was published Wednesday in the journal Nature.

Researchers at the Woods Hole Oceanographic Institution in Falmouth, Massachusetts found that glaciers on the world's second-largest island are melting more than 30 percent faster than during the mid-1900s.

In General, noted a fifty percent increase in the total volume of melt water in the ice cover since the start of the industrial era. At lower heights melt water directly runs off the ice sheet, but at escalated heights some percolates down porous compressed snow vociferated firn prior to refreezing to constitute layer not as same as the growth layers discovered in trees.

The rapid rise in surface melting over the last two decades in particular suggests a "non-linear" response to rising temperatures, meaning as global warming progresses this melting could greatly accelerate, contributing more and more to rising sea levels.

"The melting and sea level rise we've observed already will be dwarfed by what may be expected in the future as climate continues to warm".

The scientists drilled at these elevations to ensure the cores would contain records of past melt intensity, allowing them to extend their records back into the 17th Century.

They found that the surface of Greenland's ice sheet melts on summer days.

The year 2012, in particular, was a standout for ice melt. But in contrast, at higher elevations, summer meltwater quickly refreezes from contact with the below-freezing snowpack it lies on - preventing the meltwater from running off. This frozen meltwater creates distinct ice bands that pile up over years to form layers of densely packed ice.

Scientists then measured physical and chemical properties along the cores to determine the thickness and age of the melt layers. Melt layers that were thicker indicated the years in which more melting occurred, whereas thinner sections represented years with less amount of melting. Combining results of melting found in the ice cores with satellite observations and sophisticated climate models, the researchers were able to reconstruct meltwater runoff at the lower-elevation edges of the ice sheet-the areas that contribute to sea level rise.

Satellite methods to understand melting rates have only been around in recent decades, so the ability to go back further in time was important.

"We find that for every degree of warming, melting increases more and more - it outpaces the warming", added Luke Trusel, a geologist from Rowan University and also an author of the study. "Warming means more today than it did even just a few decades ago". It costs a lot to produce.

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