Comment on “An equable subtropical climate throughout China in the Miocene based on palaeofloral evidence” by Qing Wang, Yan Li David K. Ferguson, Wen-Bo Mo, and Nan Yang, Earth-Science Reviews, [Earth-Science Reviews 218 (2021) 103649]

• Published in: Earth-science reviews 2022-10, Vol.233, p.104020, Article 104020
• Main Authors: Miao, Yunfa, Xiang, Mingxing, Zhang, Teng, Warny, Sophie
• Format: Article
• Language: English
• Subjects: Aridification; Miocene; Multiple methods; Precipitation gradient; Tibetan Plateau
• ISSN: 0012-8252; 1872-6828
• DOI: 10.1016/j.earscirev.2022.104020

In their thoughtful paper entitled “An equable subtropical climate throughout China in the Miocene based on palaeofloral evidence”, Qing Wang, Yan Li, David K. Ferguson, Wen-Bo Mo, and Nan Yang (2021) imply that China exhibited negligible latitudinal mean annual precipitation (MAP) gradients and lacked arid regions during the Miocene. They also speculate that there was no abrupt change in elevation of the Tibetan Plateau, nor that the plateau attained its present altitude or orography during that period. These conclusions were derived mainly by using a co-existence approach (CA) and ‘incomplete data’. Here, we use CA with training data and also integrate a coexistence likelihood estimation, a pollen-MAP boundary, a desert-MAP boundary, and other newly published MAP data to show that Northwest China consistently exhibited drier conditions than South China and East China during the entire Miocene, with our new values being 300–500 mm lower than those of Wang et al. (2021). This implies that there were large spatial gradients of MAP in China during the Miocene, which may be directly linked with the growth of the Tibetan Plateau, the global cooling, as well as other factors. We recommend the comprehensive consideration of multiple methods and proxies for reconstructing past climate conditions as opposed to a single proxy.