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Nature 394, 847-853 (27 August 1998) | doi:10.1038/29695; Received 5 December 1997; Accepted 29 May 1998

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Simulated influence of carbon dioxide, orbital forcing and ice sheets on the climate of the Last Glacial Maximum

Andrew J. Weaver1, Michael Eby1, Augustus F. Fanning1 & Edward C. Wiebe1

  1. School of Earth and Ocean Sciences, University of Victoria, PO Box 3055, Victoria, British Columbia, V8W 3P6, Canada

Correspondence to: Andrew J. Weaver1 Correspondence and requests for materials should be addressed to A.J.W. (e-mail: Email: weaver@ocean.seos.uvic.ca).

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A coupled atmosphere–ocean–sea-ice model is used to investigate the climate of the Last Glacial Maximum (approx21,000 years ago) and the relative climate-forcing effects of atmosphere CO2, the Earth's orbital parameters and ice-sheet albedo. Tropical temperatures are found to be approx2.2 °C less than today's—slightly colder than indicated by the CLIMAP palaeoclimate reconstruction. This result is consistent with a low to medium climate sensitivity to radiative perturbations. Temperatures are colder still in the northern North Atlantic region, owing to a weakening and shallowing of the thermohaline circulation. A sensitivity analysis suggests that changes in ocean circulation since the Last Glacial Maximum have not contributed directly to the global-mean temperature change since that time.