Holocene deglaciation of Prudhoe Dome, northwest Greenland

Caleb Kazunari Walcott-George, Nathan David Brown , Jason P. Briner, Allie Balter-Kennedy , Nicolás E. Young, Tanner Kuhl, Elliot Moravec, Sridhar Anandakrishnan, Nathan Stevens, Benjamin Andrew Keisling, Robert Deconto, Vasileios Gkinis, Joerg M. Schaefer

Projections of future sea-level rise benefit from understanding the response of past ice sheets to interglacial warmth. Constraints on the extent of inland Greenland Ice Sheet (GrIS) recession during the Middle Holocene (~8 – 4 ka) are limited because geological records of a smaller-than-modern phase largely remain beneath the modern ice sheet. We drilled through 509 m of firn and ice at Prudhoe Dome (PD), northwest Greenland to obtain sub-ice material yielding direct evidence for the response of the NW GrIS to Holocene warmth. Our infrared stimulated luminescence measurements from sub-ice sediments indicates that the ground below the summit was exposed to sunlight at 7.1 ± 1.1 ka. This complete deglaciation of PD, coeval to reduced extent at other ice caps across Northern Greenland, is further supported by interglacial-only δ18O values from the PD ice column as well as ice depth-age modeling. Our results point to a significant response of the NW GrIS to early Holocene warming, estimated to be +3–5 ℃ from paleoclimate data. This range of summer temperatures is similar to projections of warming by 2100 CE.