Pat Shingleton: "Fires and Ice Melt"
It was originally thought that the large scale surface melting of the Greenland ice sheet was caused by warming. Proceedings of the National Academy of Sciences reports that the melting was due to a combination of ash from Northern Hemisphere forest fires and temperature changes. The massive Greenland ice sheet experiences annual melting at low elevations near the coastline. Surface melting is rare in its center and in 2012 more than 97 percent of the ice sheet experienced surface melt. Forest fires in Siberia and North America in June 2012 ejected high concentrations of ammonium and black carbon. Air masses from these locations arrived at the Greenland ice sheet's summit, the worlds second largest, just before the widespread melt event.