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Greenland ice sheet melting 'off the charts' as climate warms

09 December 2018

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 research team said ice core records provide "critical" historical context because satellite measurements - which scientists rely on today to understand melting rates in response to changing climate - have only been around since the late 1970s.

"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. The melting is not just increasing - it's accelerating.

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. The researchers claim that the thickness of the annual melt layers can also track how much melting was occurring at different sites, at the lower-elevations edges of the ice sheet.

Ice loss from Greenland is the single largest contributor to global sea-level rise, which is predicted to lead to inundation of low-lying islands and coastal cities around the world over the next several decades and centuries.

During warm summer days in Greenland, melting occurs across much of the ice sheet surface. I am especially enthusiastic about technology, science, and health-related issues.

The complexity of ice melting, and the potential affects on the planet of the melting Greenland ice sheet mean that we need to seriously consider what impacts our actions today will have on the future, according to Dr Trusel.

Trusel's team of global researchers analyzed ice cores extracted from Greenland, a massive island wedged between the Arctic and Atlantic Oceans.

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. A contemporary study portrays this enormous melt out wasn't only an irregularity juxtaposed with the last 40 years but the last 350.

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. With those samples, the researchers were able to create a timeline of Greenland's ice cover going back 350 years. Thicker melt layers represented years of higher melting, while thinner sections indicated years with less melting. The team combined their results from different ice cores with satellite observations of the melting and modern climate change models. The satellites used to study ice sheet melting around the world haven't been around long enough to capture a complete picture of the melting process. They found that the disappearance of the ice has accelerated after the Industrial revolution in the mid-nineteenth century, but the rampant situation acquired much later.

Researchers from the MIT-WHO Joint Program, University of Washington, Wheaton College, University of Leige, Desert Research Institute, and Utrecht University also worked on the study.

Greenland ice sheet melting 'off the charts' as climate warms