Enhanced Carbonate Counter Pump and upwelling strengths in the Indian sector of the Southern Ocean during MIS 11

Type Article
Date 2022-07
Language English
Author(s) Brandon MargauxORCID1, 2, Duchamp-Alphonse Stéphanie1, Michel Elisabeth2, Landais Amaëlle2, Isguder Gulay2, Richard Patricia2, Pige Nicolas3, Bassinot FranckORCID2, Jaccard Samuel L.4, Bartolini Annachiara5
Affiliation(s) 1 : Université Paris-Saclay, CNRS, GEOPS, 91405, Orsay, France
2 : Université Paris-Saclay, CNRS, CEA, UVSQ, Laboratoire des Sciences du climat et de l'environnement, 91191, Gif-sur-Yvette, France
3 : Univ Lyon, UCBL, ENSL, UJM, CNRS, LGL-TPE, F-69622, Villeurbanne, France
4 : Institute of Earth Sciences, University of Lausanne, 1015, Lausanne, Switzerland
5 : Muséum National d’Histoire Naturelle, Département Origines & Évolution, CR2P MNHN, CNRS, Sorbonne Université, 8 rue Buffon CP38, 75005, Paris, France
Source Quaternary Science Reviews (0277-3791) (Elsevier BV), 2022-07 , Vol. 287 , P. 107556 (14p.)
DOI 10.1016/j.quascirev.2022.107556
WOS© Times Cited 1
Keyword(s) Southern Ocean, Marine Isotope Stage 11, Coccolith, Planktonic foraminifera, Geochemistry, Carbonate Counter Pump, Upwelling, Atmospheric CO2 concentration
Abstract

While numerous studies have highlighted the central role of Southern Ocean (SO) dynamics in modulating rapid increases in atmospheric CO2 concentrations during deglaciations, fewer studies have yet focused on the impact of the Biological Carbon Pump - and more specifically the Carbonate Counter Pump (CCP) - in contributing to increase the CO2 concentration in oceanic surface waters and thus, in the atmosphere. Here, we present micropaleontological (coccolith, planktonic foraminifera) and geochemical (CaCO3, CaXRF, δ13CN. pachyderma) constraints from sediment core MD04-2718 retrieved in the Polar Front Zone of the Indian Ocean covering the time interval spanning Marine Isotope Stage (MIS) 12 to MIS 10 (440,000–360,000 years). We compare our results with published records from the SO to reconstruct past changes in CCP and upwelling dynamics and understand their leverage on the ocean-atmosphere portioning of CO2. We demonstrate that the sharp increase in atmospheric pCO2 during Termination V was likely associated with enhanced deep-water ventilation in the SO, that promoted the release of previously sequestered CO2 to the ocean surface as the westerly wind belt and the frontal system migrated southwards. Enhanced CCP is observed later, during MIS 11, and is likely the consequence of higher sea surface temperature and higher nutrient availability due to the reinvigoration of SO upwelling leading to increased coccolith (and to a lesser degree, planktonic foraminifera) production and export. The low eccentricity signal recorded during MIS 11 might have additionally strengthened the CCP, exerting a specific control on Gephyrocapsa morphotypes. In addition to the strong global biological productivity and higher carbon storage on land, these synergistic mechanisms may have permitted to shape the distinctive 30 ka-long pCO2 plateau characteristic of MIS 11.

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Brandon Margaux, Duchamp-Alphonse Stéphanie, Michel Elisabeth, Landais Amaëlle, Isguder Gulay, Richard Patricia, Pige Nicolas, Bassinot Franck, Jaccard Samuel L., Bartolini Annachiara (2022). Enhanced Carbonate Counter Pump and upwelling strengths in the Indian sector of the Southern Ocean during MIS 11. Quaternary Science Reviews, 287, 107556 (14p.). Publisher's official version : https://doi.org/10.1016/j.quascirev.2022.107556 , Open Access version : https://archimer.ifremer.fr/doc/00773/88478/