Greenland snow melting from global warming is off the charts, claims study

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In July 2012, a spate of warm weather caused almost the entire surface of the Greenland ice sheet to begin melting, an event with no precedent in the satellite record.

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

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.

They showed that melting of Greenland's surface ice began increasing in the mid-19th century and then ramped up dramatically during the 20th and early 21st centuries.

He said melting had gone "into overdrive", and as a result Greenland melt was adding to sea level more than any time during the last three-and-a-half centuries, if not thousands of years.

"From a historical perspective, today's melt rates are off the charts, and this study provides the evidence to prove this" Sarah Das, a glaciologist at Woods Hole Oceanographic Institution and coauthor of the study, said.

Total ice sheet melt-water runoff had increased 50% compared with the start of the industrial era, and had seen a 30% increase since the 20th century alone, she said.

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.

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The research team found out how intensely Greenland ice has melted in past centuries using a drill the size of a traffic light pole to extract ice cores from the ice sheet and a nearby coastal ice cap.

The cores of the drilling contained records of past melts, which allowed the scientists to extend their records back to the 17th century.

Researchers said the findings "provide new evidence of the impacts of climate change on Arctic melting and global sea level rise".

But at higher elevations the summer meltwater quickly refreezes from contact with the below-freezing snowpack sitting underneath, preventing it from escaping the ice sheet in the form of runoff.

Commenting on the report, Gareth Redmond-King, head of climate change at the World Wildlife Fund said: "If governments don't radically up their green ambitions, we're facing a future without coral reefs or Arctic summer ice, where food shortages, floods and fires are part of our everyday reality".

Dr Trusel, from Rowan University's School of Earth and Environment in New Jersey, US, said Greenland would melt more and more for every degree of warming.

"What our ice cores show is that Greenland is now at a state where it's much more sensitive to further increases in temperature than it was even 50 years ago".

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