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Fig. 19 | Progress in Earth and Planetary Science

Fig. 19

From: Perspective on the response of marine calcifiers to global warming and ocean acidification—Behavior of corals and foraminifera in a high CO2 world “hot house”

Fig. 19

Three-box model sensitivity of saturation depth and carbonate ion concentration at deep box at a high CO2 concentration (1020 ppm) (Yamamura et al. 2007). Approximately 15% of the world ocean surface area is represented by the high-latitude box. Variable T represents the large scale meridional overturning of the world ocean. Polar vertical mixing is meant to represent deep water ventilation and formation around the Antarctic continent today. Phosphate serves as the main nutrient accounting for organic carbon production. The phosphate concentration in the low-latitude surface box drives its new production by restoring the phosphate concentration to its initial value. The production rate of organic carbon from the surface ocean is expressed as the flux of phosphate, which is assumed to occur with a stoichiometry of P: Corg:-O2 = 1:117:170 (Anderson and Sarmiento 1994). In this model, the new production rate at the low-latitude surface box, which is described as Pl, depends on the upwelling supply flux of phosphate due to the thermohaline circulation. In the high-latitude box, the new production rate is fixed to a prescribed value since the productivity seems to be affected by factors other than nutrients. With the production rate, we adjust the global average export ratio of CaCO3/Corg to 0.1 based on Sarmiento et al. (2002). The solid line indicates the carbonate ion concentration (μmol/kg) and the broken line indicates saturation depth (m). The light-gray shading indicates the saturation depth below 0 m. The dark shading indicates the range of the saturation depth, similar to the interglacial value

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