Ocean Acidification From Below in the Tropical Pacific

• Published in: Global Biogeochemical Cycles
• Main Authors: Ishii, Masao, Rodgers, Keith B., Inoue, Hisayuki, Toyama, Katsuya, Sasano, Daisuke, Kosugi, Naohiro, Ono, Hisashi, Enyo, Kazutaka, Nakano, Toshiya, Iudicone, Daniele, Blanke, Bruno, Aumont, Olivier, Feely, Richard A.
• Other Authors: Japan Meteorological Agency (JMA), IBS Center for Climate Physics, Pusan National University (PNU), Hokkaido University Sapporo, Japan, Meteorological Research Institute Tsukuba (MRI), Global Environment and Marine Department Tokyo, Stazione Zoologica Anton Dohrn (SZN), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Nucleus for European Modeling of the Ocean (NEMO R&D ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-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)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), NOAA Pacific Marine Environmental Laboratory Newport (PMEL), National Oceanic and Atmospheric Administration (NOAA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: [SDE.MCG]Environmental Sciences/Global Changes; Ocean acidification
• Online Access: https://hal.science/hal-02988717; https://hal.science/hal-02988717/document; https://hal.science/hal-02988717/file/ocean%20acidification%20from%20below%20in%20the%20tropical%20pacific.pdf; https://doi.org/10.1029/2019GB006368

International audience Identifying ocean acidification and its controlling mechanisms is an important priority within the broader question of understanding how sustained anthropogenic CO 2 emissions are harming the health of the ocean. Through extensive analysis of observational data products for ocean inorganic carbon, here we quantify the rate at which acidification is proceeding in the western tropical Pacific Warm Pool, revealing −0.0013 ± 0.0001 year −1 for pH and −0.0083 ± 0.0007 year −1 for the saturation index of aragonite for the years 1985-2016. However, the mean rate of total dissolved inorganic carbon increase (+0.81 ± 0.06 μmol · kg −1 · year −1) sustaining acidification was~20% slower than what would be expected if it were simply controlled by the rate of atmospheric CO 2 increase and transmitted through local air-sea CO 2 equilibration. Joint Lagrangian and Eulerian model diagnostics indicate that the acidification of the Warm Pool occurs primarily through the anthropogenic CO 2 that invades the ocean in the extra-tropics is transported to the tropics through the thermocline shallow overturning circulation and then re-emerges into surface waters within the tropics through the Equatorial Undercurrent from below. An interior residence time of several years to decades, acting in conjunction with the accelerating CO 2 growth in the atmosphere, can be expected to contribute to modulating the rate of Warm Pool acidification.