Climate model simulations have suggested that, in East Asia, the mean precipitation increases with global warming, leading to more humid conditions. In contrast, Cretaceous proxy data show an aridification in the low latitudes of East Asia during the mid-Cretaceous when CO₂ levels were higher and the climate was relatively warmer compared to the early and late Cretaceous. We conducted simulations of the Present-day and Cretaceous climates with different CO₂ levels using an atmosphere-ocean general circulation model, MIROC4m, to investigate the hydrological cycle changes as CO₂ is increased. The results show that the responses of the hydrological cycle in East Asia for the Present-day and Cretaceous experiments are the exact opposite; an increase in the Present-day, and a decrease in the Cretaceous, as geological evidence shows. Overall, the opposite response in the Cretaceous is attributed to a weaker summer atmospheric circulation, associated with the absence of the Tibetan Plateau.

中文翻译：

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当前和白垩纪水文循环对 CO2 浓度上升的响应之间的差异

气候模型模拟表明，在东亚，平均降水量随着全球变暖而增加，导致更潮湿的条件。相比之下，白垩纪代理数据显示，与白垩纪早期和晚期相比，当 CO ₂水平较高且气候相对温暖时，东亚低纬度地区在白垩纪中期发生了干旱。我们使用大气-海洋环流模型 MIROC4m 对具有不同 CO ₂水平的现代和白垩纪气候进行了模拟，以研究作为 CO ₂的水文循环变化增加。结果表明，东亚水文循环对现代和白垩纪实验的响应正好相反；如地质证据所示，今世增加，白垩纪减少。总体而言，白垩纪的相反响应归因于夏季大气环流较弱，与青藏高原的缺失有关。