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EGU 2015, Recent and future changes in the Greenland Ice Sheet

EGU 2015, Recent and future changes in the Greenland Ice Sheet

Kristof Van Tricht
PhD Student, Dept. of Earth and Environmental Sciences
KU Leuven, Belgium
Andrew Shepherd
Professor of Earth Observation
University of Leeds, UK
Marco Tedesco
Associate Professor, Earth and Atmospheric Science Department
The City College of New York, USA
"Over the past few decades, the Arctic region has warmed more than any other on Earth. The Greenland Ice Sheet is losing mass faster than ever before, and is expected to keep melting with consequences for global sea-level rise and ocean circulation."
In addressing the theme of this press conference, the participants emphasised several issues: the interdisciplinary nature of studies in the loss of mass on the Greenland Ice Sheet and the need for cooperation therein; linked to that, uncertainty as to which processes are contributing more than others; the need to revise the last IPCC report, taking into account new developments and discoveries using the processes discussed during the press conference.
Kristof Van Tricht opened the proceedings by discussing the role of clouds in ice loss. His research, which focuses on measuring ice loss with cloud cover as against modeling without it, estimates that an extra 25GTs of ice is lost annually in the Greenland Ice Sheet due to cloud cover; a factor that had not previously been taken much into account in determining future trends. 
Andrew Shepherd, presenting on behalf of Amber Leeson (University of Leeds), discussed the effects of the inward migration of Greenland's supraglacial lakes. According to Leeson's research, drainage in these lakes causes ice-bed movement at a rate previously unheard of, which becomes a causative factor in ice loss. While the 4th IPCC report acknowledged the contribution this ultimately makes to sea-level rise, the extent of which was in fact downgraded significantly in the following report.
Lastly, Marco Tedesco spoke on "darkening" in ice. His summary on this was that darkening, associated with increased temperatures and melting levels, began just under two decades ago and was driven by increased surface snow grain size and increased impurities therein. While stating that we cannot know with certainty the degree to which this may contribute to sea-level rise (due to ice loss), Tedesco projected that darkening would continue as a consequence of continued climate warming. As this both increases meltwater, and is driven by it, he coined the term "melting cannibalism".
Although uncertainties abound about the levels of contribution these three processes make to global sea-level rise, their complete (or near complete) absence as factors under consideration in the last IPCC report is something that must be addressed. The critical message from the press conference was that any future numerical model must take these new systems - all of them, and in a complementary fashion - into account.
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