Climate of the Past Discussions www.clim-past-discuss.net 1814-9340 1814-9359 5 3 2009 10.5194/cpd-5-1463-2009 http://www.clim-past-discuss.net/5/1463/2009/ http://www.clim-past-discuss.net/5/1463/2009/cpd-5-1463-2009.html http://www.clim-past-discuss.net/5/1463/2009/cpd-5-1463-2009.pdf 1463 1491 2009-05-20 Quantifying the roles of ocean circulation and biogeochemistry in governing ocean carbon-13 and atmospheric carbon dioxide at the last glacial maximum A. Tagliabue alessandro.tagliabue@lsce.ipsl.fr L. Bopp D. M. Roche N. Bouttes J.-C. Dutay R. Alkama M. Kageyama E. Michel D. Paillard Laboratoire des Sciences du Climat et de l'Environnement, IPSL-CEA-CNRS-UVSQ, 91191 Gif sur Yvette, France Department of Palaeoclimatology and Geomorphology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands Centre National de Recherches Météorologiques (CNRM), 42 Avenue Coriolis, 31057 Toulouse, France We use a state-of-the-art ocean general circulation and biogeochemistry model to examine the impact of changes in ocean circulation and biogeochemistry in governing the change in ocean carbon-13 and atmospheric CO₂ at the last glacial maximum (LGM). We examine 5 different realisations of the ocean's overturning circulation produced by a fully coupled atmosphere-ocean model under LGM forcing and suggested changes in the atmospheric deposition of iron and phytoplankton physiology at the LGM. 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