The East and South Asian summer monsoons affect billions of people but a multitude of potential variables have precluded definitive attribution of their controlling mechanisms and hindered models of their evolution in an anthropogenically warmed climate. Atmospheric CO₂ concentrations were higher than modern during the early Pliocene and provide a potential analog for future climate. Therefore, understanding East and South Asian summer monsoons during the early Pliocene is instructive to understanding their forcing mechanisms and future variation. Here we report the first evidence for an anti‐phasing trend between the East and South Asian summer monsoons during early Pliocene time based on multiple lines of evidence. Comparison of our results with the paleoceanography records suggests that the strengthening of South Asian summer monsoons and weakening of East Asian summer monsoons during the early Pliocene were likely driven by the increase of Antarctic ice volume.

中文翻译：

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南半球冰量驱动的上新世早期南亚和东亚夏季风的反相位增强

东亚和南亚夏季风影响着数十亿人，但众多潜在变量却无法确定其控制机制的归属，并阻碍了在人为变暖的气候中其演化的模型。大气CO ₂上新世早期的大气浓度高于现代，并为未来的气候提供了潜在的类似物。因此，了解上新世初期的东亚和南亚夏季风对理解它们的强迫机制和未来变化具有指导意义。在这里，我们基于多个证据报告了上新世初期东亚和南亚夏季风之间反相位趋势的第一个证据。我们的结果与古海洋学记录的比较表明，在上新世初期南亚夏季风的增强和东亚夏季风的减弱可能是由于南极冰量的增加。