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Ocean Acidification From Below in the Tropical Pacific
Author(s) -
Ishii Masao,
Rodgers Keith B.,
Inoue Hisayuki Y.,
Toyama Katsuya,
Sasano Daisuke,
Kosugi Naohiro,
Ono Hisashi,
Enyo Kazutaka,
Nakano Toshiya,
Iudicone Daniele,
Blanke Bruno,
Aumont Olivier,
Feely Richard A.
Publication year - 2020
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2019gb006368
Subject(s) - ocean acidification , thermocline , tropics , environmental science , oceanography , atmosphere (unit) , carbon dioxide in earth's atmosphere , carbon dioxide , climatology , atmospheric sciences , seawater , geology , climate change , ecology , geography , meteorology , biology
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.