Published: Fri, December 07, 2018
Research | By Raquel Erickson

Greenland ice sheet melt 'off the charts' compared with previous four centuries

Greenland ice sheet melt 'off the charts' compared with previous four centuries

The author of the study, Dr Luke Trusel from US Rowan University, said: "Melting of the Greenland Ice Sheet has gone into overdrive". A contemporary study portrays this enormous melt out wasn't only an irregularity juxtaposed with the last 40 years but the last 350.

Published today in Nature, the research finds that rates of melting at Greenland's surface have skyrocketed in recent decades and are now far out of bounds of what was considered natural variability over the last few centuries.

"Rather than increasing steadily as climate warms, Greenland will melt increasingly more and more for every degree of warming". This means that the sea level could rise sooner and faster than previously assumed.

"The ice melting rate in Greenland today is without precedent and it is off the scale when we look back at the historical record", said Sarah Das, a researcher at Woods Hole Oceanographic Institution and co-writer of the report. "We found a fifty percent increase in total ice sheet meltwater runoff versus the start of the industrial era, and a thirty percent increase since the 20 century alone". If anyone wonders why the cores were drilled at such a high elevation - it is because the cores would contain records of past melt intensity, dating back to the 17th century.

The report comes after naturalist Sir David Attenborough warned the collapse of civilisations and extinction of much of the natural world "is on the horizon" without urgent action to tackle climate change. It suggests that if the trend of warmer summers continues causing unprecedented rates of melting it could accelerate the already fast pace of sea level rise. This frozen meltwater creates distinct ice bands that pile up over years to form layers of densely packed ice.

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. This layered pattern allows researchers to estimate how much melt took place each year, going back about 350 years. This threatens cities such as London and Venice and entire nations such as the Maldives, which within decades could be swallowed by the rising level of the sea.

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.

"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. Instead, each degree of warming increases the amount of melting, meaning the more the planet warms, the more sensitive the ice sheet will be.

"Even a very small change in temperature caused an exponential increase in melting in recent years", she said.

Additional co-authors are: Matthew J. Evans, Wheaton College; Ben E. Smith, University of Washington; Xavier Fettweis, University of Leige; Joseph R. McConnell, Desert Research Institute; and Brice P.Y. Noël and and Michiel R. van den Broeke Utrecht University.

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