Cenozoic evolution of spring persistent rainfall in East Asia and North America driven by paleogeography

Spring persistent rainfall is a unique climate phenomenon that prevails in East Asia today, providing precious water resources to this densely populated region. However, its Cenozoic history and underlying mechanisms remain poorly understood. Here we show that the spring persistent rainfall in East Asia has emerged since the Miocene, whereas it previously flourished in North America during the Eocene, as revealed by climate models integrated with climate proxies. The contrasting evolution of spring persistent rainfall in East Asia and North America is determined by paleogeography and further influenced by CO2-induced warming. The uplift of the Tibetan Plateau and the westward drift of the Rocky Mountains have triggered a mid-latitude Rossby wave train since the Miocene, altering the position and intensity of the subtropical highs and thus rainfall patterns. Our results illuminate the Cenozoic evolution of spring persistent rainfall, with implications for the spring climate under the extreme future warming. The emergence of the spring persistent rainfall in East Asia since the Miocene and its decline in North America was determined by paleogeographic events through mid-latitude Rossby wave trains, as revealed by climate models integrated with climate proxies.