Continental climate variability during the middle Eocene global warming

Middle Eocene saw several global warming events. However, the terrestrial climate linkage to the warming events is still enigmatic. Particularly, the paleoclimate of middle Eocene East Asia is unclear when the East Asian monsoons started to prevail. Here, we present a combination of high-resolution elemental, compositional and natural gamma-ray (GR) records and conduct an orbital-scale paleoclimate reconstruction for the middle Eocene lacustrine shale dated from 43.4 to 40.9 Ma in the Bohai Bay Basin, East Asia. The results show an obvious shift in orbital variability from obliquity- to eccentricitydominated cycles and an evident humidification at -41.9 Ma in the East Asia. Eccentricity maxima filtered from the terrestrial records coincide with the deep-sea temperature rises during -41.9-41.5 Ma. The terrestrial climate transition at 41.9 Ma was most likely attributed to intensification of the East Asian monsoons responding to the elevated atmospheric pCO2 during the concurrent global warming. (c) 2023 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.