Today, the ice is melting 50 percent faster than it did before industrialisation and 33 percent faster than during the 20th century.
The loss of ice from Greenland is one of the key drivers of rising global sea levels. Data suggests that even small changes in temperature caused exponential increases in melting in recent years - a non-linear response that points to feedback effects. The Arctic began to warm as humanity began to pump greenhouse gases (GHG) into the atmosphere.
Greenland's ice sheet is melting at a faster rate than previously thought and continued global warming will accelerate thawing and contribute to rising sea levels, scientists said in a paper published on Wednesday. "Anything we can do to limit future warming, even by a little bit, is going to make a huge difference to keeping ice on Greenland and not in the ocean".
"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 melting and freezing cycle also makes ice below the surface less permeable, so more runoff is shunted to the ocean rather than trickling down into the ice sheet.
The cores of the drilling contained records of past melts, which allowed the scientists to extend their records back to the 17th century. In the warmer summer months, melting occurs across much of Greenland's ice sheet surface. Contrary, at higher elevations, the meltwater quickly refreezes due to contact with the snowpack underneath.
Trusel's team of worldwide researchers analyzed ice cores extracted from Greenland, a massive island wedged between the Arctic and Atlantic Oceans. This frozen meltwater creates distinct ice bands that pile up over years to form layers of densely packed ice. The equipment was used to pore through the centuries-old ice layers. Dark bands running horizontally across the cores, like ticks on a ruler, enabled the scientists to visually chronicle the strength of melting at the surface from year to year. 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.
"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 20th century alone", Das said. Ice core records provide critical historical context because the satellites have only been recording measurements since the late 1970s, according to study co-author and graduate student Matt Osman of the MIT-WHOI Joint Program.
"The melting is not just increasing - it's accelerating", Trusel told Nature.
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".
Das and her colleagues at Rowan University and elsewhere reached that conclusion by examining three ice cores from central west Greenland, and one from an ice cap off the coast, that contain a history of melt events spanning the past 350 years.