Response of export production and dissolved oxygen concentrations in oxygen minimum zones to <i>p</i>CO<sub>2</sub> and temperature stabilization scenarios in the biogeochemical model HAMOCC 2.0
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 zone (OMZ) expansion r...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-02-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/14/781/2017/bg-14-781-2017.pdf |
| Summary: | 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 zone (OMZ) expansion respond
to changes in CO<sub>2</sub> radiative forcing. Atmospheric <i>p</i>CO<sub>2</sub> is
increased at a rate of 1 % annually and the model is stabilized at
2 ×, 4 ×, 6 ×, and 8 × preindustrial
<i>p</i>CO<sub>2</sub> levels. With an increase in CO<sub>2</sub> 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 OMZs 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 in POC
export production, vertical POC 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 is linked to increases POC
flux as well as changes in oxygen solubility with increasing seawater
temperature. Changes in total organic carbon and increase sea surface
temperature (SST) also lead to the formation of a new OMZ in the western
subtropical Pacific Ocean. The development of the new OMZ results in
dissolved oxygen concentration of ≤ 50 µmol kg<sup>−1</sup>
throughout the equatorial Pacific Ocean at 4 times preindustrial <i>p</i>CO<sub>2</sub>.
Total ocean volume with dissolved oxygen concentrations of
≤ 50 µmol kg<sup>−1</sup> increases by 2.4, 5.0, and 10.5 % for
the 2 ×, 4 ×, and 8 × CO<sub>2</sub> simulations,
respectively. |
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| ISSN: | 1726-4170 1726-4189 |