Calibrated relative sea levels constrain isostatic adjustment and ice history in northwest Greenland

Relative Sea Levels (RSLs) derived primarily from marine bivalves near Petermann Glacier, NW Greenland, constrain past regional ice-mass changes through glacial isostatic adjustment (GIA) modeling. Oxygen isotopes measured on bivalves corrected for shell-depth habitat and document changing melt-water input. Rapid RSL fall of up to 62 m/kyr indicates ice loss at or prior to-9 ka. Transition to an RSL stillstand starting at-6 ka reflects renewed ice-mass loading followed by further mass loss over the past few millennia. GIA simulations of rapid early RSL fall suggest a low regional upper-mantle viscosity. Early loss of grounded ice tracks atmospheric warming and pre-dates the eventual collapse of Petermann Glacier's floating ice tongue near-7 ka, suggesting grounding zone stabilization during early phases of deglaciation. We hypothesize mid-Holocene regrowth of regional ice caps in response to cooling and increased precipitation, following loss of the floating shelf ice. Remnants of these ice caps remain present but are now melting.(c) 2022 Published by Elsevier Ltd.

Automated summary

This study reveals past regional ice-mass changes near Petermann Glacier in NW Greenland through relative sea level data obtained from marine bivalves. The research found that there was ice loss at Petermann Glacier at or before 9,000 years ago, followed by further mass loss around 6,000 years ago. The study speculates that regional ice caps regrew during the mid-Holocene in response to cooling and increased precipitation.