Towards a better understanding of the impact of topography evolution on Asian climate over the past 50 Ma

The past decades have been rich in field-based discoveries, substantially expanding both the range and resolution of geological records documenting Cenozoic Asian tectonic evolution, climate, and landscapes. Geological evidence from sedimentary, fluvial, lacustrine, and paleobotanical archives indicates that monsoon-like precipitation seasonality was likely already established during the Paleogene greenhouse period, thereby challenging the traditional view of monsoon climate emergence. Syntheses of these proxy records, combined with paleoclimate simulations spanning 40-8 Ma and testing a range of paleogeographic configurations, have enabled the evaluation of multiple working hypotheses and provided new perspectives on the drivers of South and East Asian monsoon onset. Model results suggest that summer and winter monsoons may have evolved diachronously in response to distinct forcings, and highlight the importance of paleogeographic evolution in shaping Asian climate. Increasing continentality, due to sea level drop, the retreat of the Paratethys Sea and the emergence of the Arabian Plate, appears to have enhanced summer ITCZ migration, while East African, Anatolian-Iranian, and Tibetan-Himalayan landforms contribute to the channelling of these moisture-laden winds toward Southeast Asia. In contrast, by blocking and deflecting westerly fluxes northward, the uplift of the Tian Shan-Pamir ranges and the Mongolian Plateau likely contributed to strengthening the winter monsoon. Together, these results highlight the need for integrated multi-proxy and modeling approaches to robustly constrain the timing and drivers of Asian monsoon establishment.