Changes in deep Pacific circulation and carbon storage during the Pliocene-Pleistocene transition

• Published in: Earth and Planetary Science Letters
• Main Authors: Jian, Zhimin, Dang, Haowen, Yu, Jimin, Wu, Qiong, Gong, Xun, Stepanek, Christian, Colin, Christophe, Hu, Lili, Lohmann, Gerrit, Zhou, Xiaoli, Wan, Sui
• Other Authors: State Key Laboratory of Marine Geology Shanghai, Tongji University, Laoshan Laboratory, Australian National University (ANU), Hohai University, China University of Geosciences Wuhan (CUG), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung = Alfred Wegener Institute for Polar and Marine Research = Institut Alfred-Wegener pour la recherche polaire et marine (AWI), Helmholtz-Gemeinschaft = Helmholtz Association, Géosciences Paris Saclay (GEOPS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), South China Sea Institute of Oceanology, the National Natural Science Foundation of China (42188102, 42222603, 42176053 and 41830539), and German BMBF grants PalMod (01LP1504A) and NOPAWAC (03F0785A).
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: intensification of Northern Hemisphere Glaciation; deep Pacific; circulation; deep Pacifi,c carbon storage; foraminiferal εNd; benthic foraminiferal B/Ca; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Antarc*; Antarctic; Sea ice; Southern Ocean
• Online Access: https://hal.science/hal-04489460; https://doi.org/10.1016/j.epsl.2023.118020

International audience The global climate has been gradually cooling over the Cenozoic and is punctuated by the intensification of Northern Hemisphere Glaciation (NHG) from the latest Pliocene to earliest Pleistocene (∼3.1–2.5 millions of years ago, Ma). A decline of atmospheric CO2 is supposed as a prerequisite for the NHG, but the associated carbon-cycle processes remain elusive. Here we combine foraminiferal records of neodymium isotope and boron-calcium ratio, and simulations of an Earth system model, to investigate changes in the water-mass composition and carbonate-ion concentration of the deep Pacific Ocean during the NHG. Our proxy records have revealed a significant expansion of southern-sourced waters with increased respired carbon storage into the deep Pacific during the NHG. These changes may be explained by strengthened deep-water formation and biological-pump efficiency in the Southern Ocean due to Antarctic sea-ice growth, as suggested by our model experiments and evidence from the Sub-Antarctic region. These results provide key clues for quantifying the role of the dissolved inorganic carbon content of deep Pacific waters in modulating atmospheric CO2 during the NHG.