Quaternary Science Reviews 25 (2006) 3278–3293 Globally increased pelagic carbonate production during the Mid-Brunhes dissolution interval and the CO 2 paradox of MIS 11 Stephen Barker a,Ã,1 , David Archer b , Linda Booth c , Henry Elderfield c , Jorijntje Henderiks d , Rosalind E.M. Rickaby e a Lamont-Doherty Earth Observatory of Columbia University, P.O. Box 1000, 61 Route 9W, Palisades, NY 10964, USA b Department of Geophysical Sciences, University of Chicago, 5734 S. Ellis Avenue, Chicago, IL 60637, USA c Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK d Department of Geology and Geochemistry, Stockholm University, Svante Arrhenius va ¨g 8 C, 106 91 Stockholm, Sweden e Department of Earth Sciences, University of Oxford, Parks Road, Oxford, PX1 3PR, UK Received 6 October 2005; accepted 21 July 2006 Abstract The Mid-Brunhes dissolution interval (MBDI) represents a period of global carbonate dissolution, lasting several hundred thousand years, centred around Marine Isotope Stage (MIS) 11. Here we report the effects of dissolution in ODP core 982, taken from 1134 m in the North Atlantic. Paradoxically, records of atmospheric CO 2 from Antarctic ice-cores reveal no long term trend over the last 400 kyr and suggest that CO 2 during MIS 11 was no higher than during the present interglacial. We suggest that a global increase in pelagic carbonate production during this period, possibly related to the proliferation of the Gephyrocapsa coccolithophore, could have altered marine carbonate chemistry in such a way as to drive increased dissolution under the constraints of steady state. An increase in the production of carbonate in surface waters would cause a drawdown of global carbonate saturation and increase dissolution at the seafloor. In order to reconcile the record of atmospheric CO 2 variability we suggest that an increase in the flux of organic matter from the surface to deep ocean, associated with either a net increase in primary production or the enhanced ballasting effect provided by an increased flux of CaCO 3 , could have countered the effect of increased calcification on CO 2 . r 2006 Elsevier Ltd. All rights reserved. 1. Introduction Reconstructing the history of marine carbonate produc- tion and preservation is an important component to understanding changes in atmospheric CO 2 . Many theories attempting to explain the 30% decrease in atmospheric CO 2 during glacial periods have invoked changes in CaCO 3 production and dissolution (Berger, 1982; Broecker and Peng, 1987; Boyle, 1988; Archer and Maier-Reimer, 1994). While the glacial–interglacial (G–IG) pattern of atmo- spheric CO 2 variability has yet to be adequately explained, longer term evolution, as documented by Antarctic ice cores, is thought to have behaved rather consistently for the last 400 ka or so, alternating between relatively constant glacial (low) and interglacial (high) values (Petit et al., 1999). In particular, CO 2 during MIS 11 appears to have been no higher than the pre-industrial Holocene (Raynaud et al., 2005). However, the record of marine carbonate preservation tells a different story; regular G–IG variations are superimposed upon a longer term variability not reflected by atmospheric CO 2 . This is paradoxical since the ocean and atmospheric carbon cycles are thought to be inextricably linked (Broecker, 1982a). Marine records from around the globe reveal a period of carbonate dissolution beginning roughly 600 kyr ago and lasting approximately 400 kyr, with a maximum intensity at around 400 kyr ago during Marine Isotope Stage (MIS) 11. ARTICLE IN PRESS 0277-3791/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.quascirev.2006.07.018 Ã Corresponding author. E-mail address: steve@earth.cf.ac.uk (S. Barker). 1 Also at School of Earth, Ocean and Planetary Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3YE, UK.