1. Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Oe, Denmark
2. Glaciology Section, Terrain Sciences Division, Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, Canada K1A 0E8
3. Laboratoire de Glaciologie et Géophysique de l'Environnement, CNRS/UJF, BP 96, 38402 Saint-Martin-d'Hères, France
4. Arctic and Antarctic Research Institute, 38 Bering Street, St Petersburg 199397, Russia
5. Deceased.

Correspondence to: B. M. Vinther¹ Correspondence and requests for materials should be addressed to B.M.V. (Email: bo@gfy.ku.dk).

On entering an era of global warming, the stability of the Greenland ice sheet (GIS) is an important concern¹, especially in the light of new evidence of rapidly changing flow and melt conditions at the GIS margins². Studying the response of the GIS to past climatic change may help to advance our understanding of GIS dynamics. The previous interpretation of evidence from stable isotopes (¹⁸O) in water from GIS ice cores was that Holocene climate variability on the GIS differed spatially³ and that a consistent Holocene climate optimum—the unusually warm period from about 9,000 to 6,000 years ago found in many northern-latitude palaeoclimate records⁴—did not exist. Here we extract both the Greenland Holocene temperature history and the evolution of GIS surface elevation at four GIS locations. We achieve this by comparing ¹⁸O from GIS ice cores^{3, 5} with ¹⁸O from ice cores from small marginal icecaps. Contrary to the earlier interpretation of ¹⁸O evidence from ice cores^{3, 6}, our new temperature history reveals a pronounced Holocene climatic optimum in Greenland coinciding with maximum thinning near the GIS margins. Our ¹⁸O-based results are corroborated by the air content of ice cores, a proxy for surface elevation⁷. State-of-the-art ice sheet models are generally found to be underestimating the extent and changes in GIS elevation and area; our findings may help to improve the ability of models to reproduce the GIS response to Holocene climate.

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