While natural patterns of certain atmospheric and ocean conditions are already known to influence Greenland melt, the study highlights the importance of a long-term warming trend to account for the unprecedented west Greenland melt rates in recent years. The researchers suggest that climate change most likely associated with human greenhouse gas emissions is the probable cause of the additional warming.
"We see that west Greenland melt really started accelerating about twenty years ago," said Erich Osterberg, assistant professor of earth sciences at Dartmouth and the lead scientist on the project. "Our study shows that the rapid rise in west Greenland melt is a combination of specific weather patterns and an additional long-term warming trend over the last century."
According to research cited in the study, loss of ice from Greenland is one of the largest contributors to global sea level rise. Although glaciers calving into the ocean cause much of the ice loss in Greenland, other research cited in the study shows that the majority of ice loss in recent years is from increased surface melt and runoff.
While satellite measurements and climate models have detailed this recent ice loss, there are far fewer direct measurements of melt collected from the ice sheet itself. For this study, researchers from Dartmouth and Boise State University spent two months on snowmobiles to collect seven ice cores from the remote "percolation zone" of the West Greenland Ice Sheet.
When warm temperatures melt snow on the surface of the percolation zone, the melt water trickles down into the deeper snow and refreezes into ice layers. Researchers were easily able to distinguish these ice layers from the surrounding compacted snow in the cores, preserving a history of how much melt occurred back through time. The more melt, the thicker the ice layers.
Read more at West Greenland Ice Sheet Melting at the Fastest Rate in Centuries
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