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

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Yau, Audrey M. and Bender, Michael L. and Robinson, Alexander James and Brook, Edward J. (2016) Reconstructing the last interglacial at Summit, Greenland: Insights from GISP2. Proceedings of the National Academy of Sciences of the United States of America, 113 (35). pp. 9710-9715. ISSN 0027-8424

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Official URL: http://dx.doi.org/10.1073/pnas.1524766113


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Abstract

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 degrees 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 CH_4 and delta O^18 of O_2, 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 d^18 O_ice, d^15N of N_2, and total air content for samples dating discontinuously from 128 to 115 ka indicate a warming of similar to 6 degrees 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.


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© 2016 National Academy of Sciences.
We thank the members of the National Ice Core Laboratory for their support in recovering samples from the ice core archive. We are grateful to Mahe Perrette for help with the statistical analysis. 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 Seventh Framework Programme [Project PIEF-GA-2012-331835; European Ice Sheet Modeling Initiative (EURICE)] and the Spanish Ministerio de Economía y Competitividad [Project CGL2014-59384-R; Modeling Abrupt Climate Change (MOCCA)]. M.L.B. was funded by the Princeton-BP Amoco Carbon Mitigation Initiative.

Uncontrolled Keywords:Sea-level rise; Ice-sheet contribution; Air content; Climatic parameters; Local insolation; Isotope records; Oxygen-isotope; Antarctic ice; Core project; Polar ice
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:40001
Deposited On:11 Nov 2016 15:18
Last Modified:10 Dec 2018 15:04

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