Quantitative Cenozoic climatic reconstruction and its implications for aridification of the northeastern Tibetan Plateau

The Cenozoic aridification of the northeastern Tibetan Plateau, together with its driving mechanisms, have been intensively investigated and debated over the past several decades. In order to contribute to the debate, we quantitatively reconstructed paleoclimatic variables (mean annual temperature and precipitation, winter and summer temperatures) for the Qaidam Basin (NE Tibetan Plateau) during the Cenozoic. Multiple methodologies (regression-based, analogue-based, and machine-learning based approaches) were applied to palynological records at the level of plant functional types. The different approaches yield similar results and they provide a robust paleoclimatic record. The results reveal a stepwise cooling and drying with the major transitions occurring at similar to 43 Ma and similar to 14 Ma. We suggest that the aridity at similar to 43 Ma may have been related to the uplift of the Tibetan Plateau, while the aridity after similar to 14 Ma may have been related to the global cooling.