Enhanced Continental Weathering Contributed to the Termination of the Middle Miocene Climatic Optimum

The Middle Miocene Climatic Optimum (MMCO, ca. 17.0 to 14.7 million years (Myr) ago) is a period of global warming that could be relevant to future projections for 2100 AD. However, the mechanism of atmospheric CO 2 removal during this interval, particularly, whether silicate weathering is critically involved, is currently unclear. In this study, a well‐dated silicate weathering record of a red clay section in East Asia during the 19.8–12.8 Myr ago interval was reported, and the silicate weathering intensity from <5 μm fraction samples was used to minimize grain‐size effects when tracing the Miocene weathering history. The results show an increase in the intensity of silicate weathering in East Asia during the MMCO. The reported data and previously published records indicate that continental weathering was enhanced in East Asia and potentially elsewhere during the MMCO, which triggered the termination of the climatic optimum.