Sep 21, 2016

Geodetic measurements reveal similarities between post–Last Glacial Maximum and present-day mass loss from the Greenland ice sheet

by
Shfaqat A. Khan, Ingo Sasgen, Michael Bevis, Tonie van Dam, Jonathan L. Bamber, John Wahr, Michael Willis, Kurt H. Kjær, Bert Wouters, Veit Helm, Beata Csatho, Kevin Fleming, Anders A. Bjørk, Andy Aschwanden, Per Knudsen, Peter Kuipers Munneke
,
Science Advances
  • States that accurate quantification of the millennial-scale mass balance of the Greenland ice sheet (GrIS) and its contribution to global sea-level rise remain challenging because of sparse in situ observations in key regions
  • Uses data from the Greenland Global Positioning System network to directly measure GIA and estimate basin-wide mass changes since the LGM
  • Finds that there are unpredicted, large GIA uplift rates of +12 mm/year in southeast Greenland
  • Finds that these rates are due to low upper mantle viscosity in the region, from when Greenland passed over the Iceland hot spot about 40 million years ago
  • Finds this region of concentrated soft rheology has a profound influence on reconstructing the deglaciation history of Greenland
  • Reevaluates the evolution of the GrIS since LGM and obtains a loss of 1.5-m sea-level equivalent from the northwest and southeast
  • States these same sectors are dominating modern mass loss
  • Suggests that the present destabilization of these marine-based sectors may increase sea level for centuries to come
  • The new deglaciation history and GIA uplift estimates suggest that studies that use the Gravity Recovery and Climate Experiment satellite mission to infer present-day changes in the GrIS may have erroneously corrected for GIA and underestimated the mass loss by about 20 gigatons/year