Atmospheric carbon dioxide and ocean circulation changes during the middle Miocene climate transition

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In a recent study based on boron isotopes in planktic foraminifera, we found that after the mid-Miocene Antarctic glaciation atmospheric pCO2 rose rapidly before returning to pre-glaciation values, which is surprising since it is opposite to what was widely assumed in the literature. We conclude that this transient rise in pCO2 is supposedly caused by enhanced meridional deep-ocean circulation. We need, however, to verify our hypothesis by investigating Miocene sediment cores from different areas and different depths to (1) eventually observe changes in ocean circulation from benthic records, and (2) to consolidate pCO2 records from the planktic records. The middle Miocene is still a hot topic among paleoclimatologists, and may provide insights into the tight coupling between Antarctic ice and the global carbon cycling. This time interval is especially interesting, because atmospheric pCO2 appears to have been similar to today and we are going to face the reversal of the middle Miocene climate transition, i.e. a substantial reduction in Antarctic ice volume. Hence the knowledge of processes involved in the interaction between mid-Miocene ice volume and global carbon cycle may be important for future predictions of our warming planet.