Greenland’s ice sheet is melting at its fastest rate in 350 years

Rodiano Bonacci
Dicembre 6, 2018

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

Global warming is melting ice in Greenland at "unprecedented rates", experts warned.

The melting of Greenland's ice sheet has accelerated to unprecedented rates in the face of rising temperatures, analysis of ice cores has found.

"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", he said.

Ice sheet melting began to increase on the 3,000-metre thick ice sheet soon after the Industrial Revolution in the 1800s but was the most extensive in 2012.

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.

From these numbers, the researchers estimated that ice sheet-wide levels of meltwater runoff have jumped 50 per cent in the past 20 years compared with pre-industrial times.

The world has already warmed by nearly 1C since pre-industrial times, and there are concerns that the ice sheet could reach a tipping point at around 1.5C to 2C of warming, lead author Luke Trusel said. Researchers provided new evidence showing the impact of climate change on Arctic melting and global sea level rises, published by scientific journal Nature.

But more than half of water from the ice sheet that goes into the ocean comes from meltwater runoff, researchers said.

Dr Trusel said: "We see melting and runoff from Greenland start ticking up as warming initiated in the Arctic in the 1800s, but only in the last few decades has it really accelerated to levels we haven't seen before in the last few centuries".

"As a result, Greenland melt is adding to sea level more than any time during the last three-and-a-half centuries, if not thousands of years".

At lower elevations, meltwater simply runs off the ice sheet, but at higher elevations some percolates down through porous, compacted snow called firn before refreezing to form layers not unlike the growth layers found in trees.

Instead, it forms distinct icy bands that stack up in layers of densely packed ice over time.

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

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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