Reconstruction of marine CO₂ dynamics of North Pacific Intermediate Water during the last deglaciation using boron isotope analyses of benthic foraminifera collected from marine sediment cores from offshore of Shimokita Peninsula

Abstract

It is widely believed that carbon stored in the deep ocean during the Last Glacial Maximum (~20,000 years ago) was released back into the atmosphere during the last deglaciation, contributing significantly to the observed rise in atmospheric CO₂. However, the exact pathways and mechanisms behind this carbon transfer remain unclear. In this study, we reconstruct changes in ocean chemistry, including the carbonate system of the Pacific intermediate water, during the last deglaciation by analyzing boron isotopes and trace element compositions of benthic foraminifera (Uvigerina spp.) from two sediment cores collected off the Shimokita Peninsula, Japan. By integrating our results with existing records of dissolved oxygen fluctuations, we further discuss the implications for global ocean carbon cycle dynamics during this critical climatic transition.