The following results are parts of the RITE in-house R&D on CO₂ ocean sequestration.

Research on the Mitigation Effect on Surface Ocean Acidification by CO₂ Ocean Sequestration

The increase of CO₂ concentration in the atmosphere is thought to cause not only the global warming but also ocean acidification because CO₂ dissolved in the ocean decreases pH in the surface layer of seawater. Then, how much acidification happens in an oceanic surface when the CO₂ emission continues as it is? How effective is the CO₂ ocean sequestration? To clarify these problems, we are researching by using a global model.

Outline of global numerical simulation model
Global numerical simulation model is constituted by physical model and ecosystem model. The physical model used in this study is Version 2 of the GFDL Modular Ocean Model (MOM2; Pacanowski, 1996). The ecosystem model is lower-trophic marine ecosystem model (Nakata and Doi, 2004).

The result of the simulation suggested causing the acidification in the mid and deep layer corresponding to the amount of CO₂ sequestration. It suggested that CO₂ ocean sequestration could decrease the acidification in the ocean surface. The condition of CO₂ ocean sequestration to restrain both a surface and a mid and deep layer acidification seems to be clarified according to a current research.

The surface layer of the ocean is the habitat of various organisms, and has larger population than the mid and deep layer. It is thought that the acidification in mid and deep layer is suppressed to lower by appropriate amount of CO₂ ocean sequestration, and the impact of the acidification on the organisms of the surface layer can be decreased.

Well, it is necessary to consider the safety of the organisms that lives in the mid and deep layer to execute CO₂ ocean sequestration. Therefore, we are researching the influence of CO₂ on the organisms. It is introduced in this page's "Research on Deep-sea Organisms Food Webs to Develop the Methodology for Predicting Ecosystem Impact" and CO₂ ocean sequestration project page.

Research on Deep-sea Organisms Food Webs to Develop the Methodology for Predicting Ecosystem Impact

This study aims at determining the food web structure of deep-sea by means of stable isotope ratios (delta13C and delta15N) of organisms to provide base information necessary for detecting such alterations of the ecosystem by CO₂ sequestrations.

Above schematic shows the food web structure of the research area. This result contributed to develop a deep-sea ecosystem model.