Article
Nature 389, 929-935 (30 October 1997) | doi:10.1038/40073; Received 12 September 1996; Accepted 3 September 1997
Contribution of Southern Ocean surface-water stratification to low atmospheric CO2 concentrations during the last glacial period
Roger Franois1, Mark A. Altabet2, Ein-Fen Yu3, Daniel M. Sigman4, Michael P. Bacon1, Martin Frank5, Gerhard Bohrmann6, Gilles Bareille7 and Laurent D. Labeyrie8
- Department of Marine Chemistry and Geochemistry,
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
- Department of Chemistry and Biochemistry and Center for Marine Science and Technology, University of Massachusetts, North Dartmouth, Massachusetts 02747, USA
- Department of Earth Sciences, National Taiwan Normal University, Taipe, 117 Taiwan
- Department of Earth Sciences, University of Oxford, Oxford OX1 3PR, UK
- GEOMAR Research Center for Marine Geosciences, 24148 Kiel, Germany
- Département de Géologie et Océanographie, Université de Bordeaux I, Talence, 33405 Cedex, France
- Centre des Faibles Radioactivités, Laboratoire mixte CNRS-CEA, Gif-sur-Yvette, 91198 Cedex, France
Correspondence to: Roger Franois1 Correspondence and requests for materials should be addressed to R.F. (e-mail: Email: rfrancois@whoi.edu).
Abstract
The nitrogen-isotope record preserved in Southern Ocean sediments, along with several geochemical tracers for the settling fluxes of biogenic matter, reveals patterns of past nutrient supply to phytoplankton and surface-water stratification in this oceanic region. Areal averaging of these spatial patterns indicates that reduction of the CO2 'leak' from ocean to atmosphere by increased surface-water stratification south of the Polar Front made a greater contribution to the lowering of atmospheric CO2 concentration during the Last Glacial Maximum than did the increased export of organic carbon from surface to deep waters occurring further north.