Publication Date:
2016-01-18
Description:
Dissolved oxygen (DO) concentration in the ocean is an important component of marine biogeochemical cycles and will be greatly altered as climate change persists. In this study a global oceanic carbon cycle model (HAMOCC 2.0) is used to address how mechanisms of oxygen minimum zones (OMZ) expansion respond to changes in CO2 radiative forcing. Atmospheric pCO2 is increased at a rate of 1% annually and the model is stabilized at 2 X, 4 X, 6 X, and 8 X preindustrial pCO2 levels. With an increase in CO2 radiative forcing, the OMZ in the Pacific Ocean is controlled largely by changes in particulate organic carbon (POC) export, resulting in increased remineralization and thus expanding the oxygen minimum zones within the tropical Pacific Ocean. A potential decline in primary producers in the future as a result of environmental stress due to ocean warming and acidification could lead to a substantial reduction of vertical carbon flux and thus increased DO concentration particularly in the Pacific Ocean at a depth of 600-800 m. In contrast, the vertical expansion of the OMZs within the Atlantic and Indian Oceans are linked to reduced oxygen solubility due to rise in potential temperature and to a lesser extent changes in remineralization rates. Changes in oxygen solubility also lead to the formation of a new OMZ in the western subtrobical Pacific Ocean. The development of the new OMZ results in dissolved oxygen concentration of ≤50 μmols throughout the equatorial Pacific Ocean at 4 times preindustrial pCO2. Total ocean area with dissolved oxygen concentrations of ≤50 μmols increases by 2.5%, 4.5%, and 7.6% for the 2 X, 4X, and 8 X CO2 simulations, respectively.
Print ISSN:
1810-6277
Electronic ISSN:
1810-6285
Topics:
Biology
,
Geosciences
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