Reconstructing the last interglacial at Summit, Greenland: Insights from GISP2

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Yau, Audrey M., Bender, Michael L., Robinson, Alexander, Brook, Edward J.
• Other Authors: Ministerio de Economía y Competitividad (España)
• Format: Article in Journal/Newspaper
• Language: English
• Published: National Academy of Sciences (U.S.) 2016
• Subjects: Greenland ice sheet; Last interglacial; Ice cores; Sea level rise; Arctic; Greenland; Greenland ice core; Greenland Ice core Project; Greenland Ice Sheet Project; ice core; Ice Sheet; NGRIP; North Greenland; North Greenland Ice Core Project
• Online Access: http://hdl.handle.net/10261/137231; https://doi.org/10.1073/pnas.1524766113; https://doi.org/10.13039/501100003329

The Eemian (last interglacial, 130–115 ka) was likely the warmest of all interglacials of the last 800 ka, with summer Arctic temperatures 3–5 °C above present. Here, we present improved Eemian climate records from central Greenland, reconstructed from the base of the Greenland Ice Sheet Project 2 (GISP2) ice core. Our record comes from clean, stratigraphically disturbed, and isotopically warm ice from 2,750 to 3,040 m depth. The age of this ice is constrained by measuring CH4 and δ18O of O2, and comparing with the historical record of these properties from the North Greenland Ice Core Project (NGRIP) and North Greenland Eemian Ice Drilling (NEEM) ice cores. The δ18Oice, δ15N of N2, and total air content for samples dating discontinuously from 128 to 115 ka indicate a warming of ∼6 °C between 127–121 ka, and a similar elevation history between GISP2 and NEEM. The reconstructed climate and elevation histories are compared with an ensemble of coupled climate-ice-sheet model simulations of the Greenland ice sheet. Those most consistent with the reconstructed temperatures indicate that the Greenland ice sheet contributed 5.1 m (4.1–6.2 m, 95% credible interval) to global eustatic sea level toward the end of the Eemian. Greenland likely did not contribute to anomalously high sea levels at ∼127 ka, or to a rapid jump in sea level at ∼120 ka. However, several unexplained discrepancies remain between the inferred and simulated histories of temperature and accumulation rate at GISP2 and NEEM, as well as between the climatic reconstructions themselves. This work was supported by grants PLR 1107343 and 1107744 from the U.S. National Science Foundation. A.R. was funded by the Marie Curie 7th Framework Programme (Project PIEF-GA-2012-331835, EURICE) and the Spanish Ministerio de Economía y Competitividad (Project CGL2014-59384- R, MOCCA). Peer reviewed