title: Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes.
abstract: Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO2 that remain unexplained. While the role of the Southern Ocean as a 'control valve' on ocean-atmosphere CO2 exchange has been emphasized, the exact nature of this role, in particular the relative contributions of physical (for example, ocean dynamics and air-sea gas exchange) versus biological processes (for example, export productivity), remains poorly constrained. Here we combine reconstructions of bottom-water [O2], export production and (14)C ventilation ages in the sub-Antarctic Atlantic, and show that atmospheric CO2 pulses during the last glacial- and deglacial periods were consistently accompanied by decreases in the biological export of carbon and increases in deep-ocean ventilation via southern-sourced water masses. These findings demonstrate how the Southern Ocean's 'organic carbon pump' has exerted a tight control on atmospheric CO2, and thus global climate, specifically via a synergy of both physical and biological processes.
authors.affiliation: Godwin Laboratory for Palaeoclimate Research, Earth Sciences Department, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK.
authors.forename: Julia
authors.identifier: http://orcid.org/0000-0002-0403-3059
authors.initials: J
authors.lastname: Gottschalk
authors.affiliation: Godwin Laboratory for Palaeoclimate Research, Earth Sciences Department, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK.
authors.forename: Luke C
authors.initials: LC
authors.lastname: Skinner
authors.affiliation: Institute of Geological Sciences and Oeschger Center for Climate Change Research, University of Bern, Baltzerstr. 1-3, Bern 3012, Switzerland.
authors.forename: Jörg
authors.initials: J
authors.lastname: Lippold
authors.affiliation: Institute of Geological Sciences and Oeschger Center for Climate Change Research, University of Bern, Baltzerstr. 1-3, Bern 3012, Switzerland.
authors.forename: Hendrik
authors.identifier: http://orcid.org/0000-0002-9902-8120
authors.initials: H
authors.lastname: Vogel
authors.affiliation: Institute of Environmental Physics, University of Heidelberg, Im Neuenheimer Feld 229, Heidelberg 69120, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Frank
authors.affiliation: Institute of Geological Sciences and Oeschger Center for Climate Change Research, University of Bern, Baltzerstr. 1-3, Bern 3012, Switzerland.
authors.forename: Samuel L
authors.initials: SL
authors.lastname: Jaccard
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CNRS-CEA-UVSQ, Université de Paris-Saclay, Domaine du CNRS, bât. 12, Gif-sur-Yvette 91198, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Waelbroeck
mesh_terms: D001272:Atmosphere / Q000737:chemistry*; D002244:Carbon / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis*; D002247:Carbon Isotopes; D057965:Carbon Sequestration; D046448:Ice Cover; D008345:Manganese / Q000032:analysis; D009792:Oceans and Seas; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis; D014501:Uranium / Q000032:analysis; D014867:Water / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D014867:Water; D002245:Carbon Dioxide; D008345:Manganese; D014501:Uranium; D002244:Carbon; D010100:Oxygen