[M-IS05] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

[MIS05-11] Modeling the ocean carbon cycle during the last deglaciation

*Hidetaka Kobayashi¹, Akira Oka¹, Takashi Obase¹, Ayako Abe-Ouchi¹ (1.Atmosphere and Ocean Research Institute, The University of Tokyo)

Keywords:ocean carbon cycle, last deglaciation, Atlantic meridional overturning circulation, Southern Ocean

Ice core records show that the atmospheric carbon dioxide concentration (pCO2) varied with an amplitude of about 100 ppm during glacial-interglacial cycles. Although not yet fully understood, it is recognized that the variation of atmospheric pCO2 is mainly due to changes in the ocean carbon cycle (e.g., sea surface temperature, biological carbon pump, ocean circulation, and carbonate inorganic chemistry). Recent studies, including those of the authors, point to the importance of changes in the Southern Ocean for the changes in the ocean carbon cycle. On the other hand, these consequences are mainly derived from comparisons of the carbon cycle under equilibrium climates, and more practically, the mechanisms of the transient responses of the carbon cycle that occur in the context of temporal changes in climate need to be finally clarified. Using the results of our modeling study, in which a complex coupled atmosphere-ocean general circulation model reproduces well the deep ocean circulation and surface temperature changes during the Bolling-Allerod (BA) transition, we investigate the transient response of the ocean carbon cycle during the last deglaciation between 21,000 and 11,000 years ago. We report the preliminary results of the transient simulation. In particular, we focus on the response of the ocean carbon cycle to rapid changes in the Atlantic meridional overturning circulation during the BA transition.