Enhanced ocean-atmosphere carbon partitioning via the carbonate counter pump during the last deglacial

• Published in: Nature Communications
• Main Authors: Duchamp-Alphonse, Stéphanie, Siani, Giuseppe, Michel, Elisabeth, Beaufort, Luc, Gally, Yves, Jaccard, Samuel
• Other Authors: Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Geological Sciences Bern, University of Bern, Oeschger Centre for Climate Change Research (OCCR), French INSU/LEFE - CHICO project; Swedish Research Council VR-349-2012-6278, Swiss National Science Foundation PP00P2-144811, PP00P2_172915
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: NATURAL IRON FERTILIZATION; DEEP SOUTHERN-OCEAN; ICE-AGE; COCCOLITHOPHORE CALCIFICATION; CO2 CONCENTRATION; EXPORT PRODUCTION; ORGANIC-MATTER; PHYTOPLANKTON; PRESERVATION; VENTILATION; [SDU]Sciences of the Universe [physics]; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Southern Ocean; Pacific
• Online Access: https://hal.archives-ouvertes.fr/hal-01819587; https://hal.archives-ouvertes.fr/hal-01819587/document; https://hal.archives-ouvertes.fr/hal-01819587/file/2018_Duchamp-Alphonse_Nature%20Communications_1.pdf; https://doi.org/10.1038/s41467-018-04625-7

International audience Several synergistic mechanisms were likely involved in the last deglacial atmospheric pCO$_2$ rise. Leading hypotheses invoke a release of deep-ocean carbon through enhanced convection in the Southern Ocean (SO) and concomitant decreased efficiency of the global soft-tissue pump (STP). However, the temporal evolution of both the STP and the carbonate counter pump (CCP) remains unclear, thus preventing the evaluation of their contributions to the pCO$_2$ rise. Here we present sedimentary coccolith records combined with export production reconstructions from the Subantarctic Pacific to document the leverage the SO biological carbon pump (BCP) has imposed on deglacial pCO$_2$. Our data suggest a weakening of BCP during the phases of carbon outgassing, due in part to an increased CCP along with higher surface ocean fertility and elevated [CO$_{2aq}$]. We propose that reduced BCP efficiency combined with enhanced SO ventilation played a major role in propelling the Earth out of the last ice age.