title: Covariation of deep Southern Ocean oxygenation and atmospheric CO2 through the last ice age.
abstract: No single mechanism can account for the full amplitude of past atmospheric carbon dioxide (CO2) concentration variability over glacial-interglacial cycles. A build-up of carbon in the deep ocean has been shown to have occurred during the Last Glacial Maximum. However, the mechanisms responsible for the release of the deeply sequestered carbon to the atmosphere at deglaciation, and the relative importance of deep ocean sequestration in regulating millennial-timescale variations in atmospheric CO2 concentration before the Last Glacial Maximum, have remained unclear. Here we present sedimentary redox-sensitive trace-metal records from the Antarctic Zone of the Southern Ocean that provide a reconstruction of transient changes in deep ocean oxygenation and, by inference, respired carbon storage throughout the last glacial cycle. Our data suggest that respired carbon was removed from the abyssal Southern Ocean during the Northern Hemisphere cold phases of the deglaciation, when atmospheric CO2 concentration increased rapidly, reflecting--at least in part--a combination of dwindling iron fertilization by dust and enhanced deep ocean ventilation. Furthermore, our records show that the observed covariation between atmospheric CO2 concentration and abyssal Southern Ocean oxygenation was maintained throughout most of the past 80,000 years. This suggests that on millennial timescales deep ocean circulation and iron fertilization in the Southern Ocean played a consistent role in modifying atmospheric CO2 concentration.
authors: Institute of Geological Sciences, University of Bern, Bern, Switzerland.|Oeschger Center for Climate Change Research, University of Bern, Bern, Switzerland.
authors: Samuel L
authors: SL
authors: Jaccard
authors: Department of Earth and Planetary Sciences, McGill University, Montreal, Canada.|Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.|Institut de Ciència i Tecnologia Ambientals and Department of Mathematics, Universitat Autonoma de Barcelona, Barcelona, Spain.
authors: Eric D
authors: ED
authors: Galbraith
authors: Geological Institute, ETH Zurich, Zurich, Switzerland.|Climate Geochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany.
authors: Alfredo
authors: A
authors: Martínez-García
authors: Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, USA.
authors: Robert F
authors: RF
authors: Anderson
mesh_terms: D000864:Antarctic Regions; D001272:Atmosphere / Q000737:chemistry*; D002245:Carbon Dioxide / Q000032:analysis* / Q000266:history / Q000378:metabolism; D057965:Carbon Sequestration; D019069:Cell Respiration; D002980:Climate; D004391:Dust; D019015:Geologic Sediments / Q000737:chemistry; D049690:History, Ancient; D046448:Ice Cover; D007501:Iron / Q000032:analysis / Q000737:chemistry; D009792:Oceans and Seas; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis* / Q000378:metabolism; D012623:Seawater / Q000737:chemistry*; D013696:Temperature; D014872:Water Movements
chemical_list: D004391:Dust; D002245:Carbon Dioxide; D007501:Iron; D010100:Oxygen