From the Daily Kos:
Another headline to get used to reading: Greenland ice may be melting faster than previously thought
By Meteor Blades
6 January 2016
|Meltwater pours into un moulin bleu in Greenland.|
A new scientific study published Monday at Nature Climate Change concludes that more melt water from Greenland may be running off into the ocean than previously calculated. That, of course, means the eventual impact the melting ice sheet of the world’s largest island has on rising sea levels could happen sooner than expected.
For several years, the international team of scientists led by Horst Machguth of the Geological Survey of Denmark and Greenland have been studying “firn.” This is porous snow resting just under the surface atop dense glacier ice. Because of its porosity, firn contains spaces that hold meltwater. Over time, this firn-held meltwater descends into the glacer where it freezes hard, which keeps it from running off. The study evaluated whether climate change has affected firn’s capacity for holding meltwater. According to the scientists, it has:
Our observations frame the recent exceptional melt summers in 2010 and 2012 (refs 5,6), revealing significant changes in firn structure at different elevations caused by successive intensive melt events. In the upper regions (more than ∼1,900 m[eters] above sea level), firn has undergone substantial densification, while at lower elevations, where melt is most abundant, porous firn has lost most of its capability to retain meltwater. Here, the formation of near-surface ice layers renders deep pore space difficult to access, forcing meltwater to enter an efficient surface discharge system and intensifying ice sheet mass loss earlier than previously suggested.