Geodetic measurements reveal similarities between post-Last Glacial Maximum and present-day mass loss from the Greenland ice sheet.
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. Glacial isostatic adjustment (GIA) is the ongoing response of the solid Earth to ice and ocean load changes occurring since the Last Glacial Maximum (LGM; ~21 thousand years ago) and may be used to constrain the GrIS deglaciation history. We use data from the Greenland Global Positioning System network to directly measure GIA and estimate basin-wide mass changes since the LGM. Unpredicted, large GIA uplift rates of +12 mm/year are found in southeast Greenland. 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. This region of concentrated soft rheology has a profound influence on reconstructing the deglaciation history of Greenland. We reevaluate the evolution of the GrIS since LGM and obtain a loss of 1.5-m sea-level equivalent from the northwest and southeast. These same sectors are dominating modern mass loss. We suggest that the present destabilization of these marine-based sectors may increase sea level for centuries to come. Our 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.
DTU Space, National Space Institute, Department of Geodesy, Technical University of Denmark, Kgs. Lyngby, Denmark.
Shfaqat A
0000-0002-2689-8563
SA
Khan
Glaciology Section, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.
Ingo
I
Sasgen
Geodetic Science, Ohio State University, Columbus, OH 43320, USA.
Michael
0000-0002-4944-8186
M
Bevis
Faculty of Science, Technology, and Communication, Research Unit of Engineering Sciences, University of Luxembourg, Luxembourg, Luxembourg.
Tonie
0000-0001-6562-6563
T
van Dam
Bristol Glaciology Centre, University of Bristol, Bristol, U.K.
Jonathan L
JL
Bamber
Department of Physics and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA.
John
J
Wahr
Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY 14853, USA.
Michael
0000-0001-7872-770X
M
Willis
Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.
Kurt H
KH
Kjær
Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, Netherlands.
Bert
B
Wouters
Glaciology Section, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.
Veit
0000-0001-7788-9328
V
Helm
Department of Geology, University at Buffalo, Buffalo, NY 14260, USA.
Beata
0000-0001-7768-4998
B
Csatho
Centre for Early Warning Systems Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany.
Kevin
0000-0001-8449-3081
K
Fleming
Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.
Anders A
0000-0002-4919-792X
AA
Bjørk
Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
Andy
0000-0001-8149-2315
A
Aschwanden
DTU Space, National Space Institute, Department of Geodesy, Technical University of Denmark, Kgs. Lyngby, Denmark.
Per
0000-0003-4640-6746
P
Knudsen
Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, Netherlands.
Peter Kuipers
PK
Munneke
GPS; Greenland Ice Sheet; Last Glacial Maximum; Sea level rise; climate change; glacial isostatic adjustment
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