Antarctic ice expansion forced climatic divergence in East and Central Asia at 2.0 Ma

Moisture and energy transport across mid-latitude Asia, controlled jointly by the Westerlies and the East Asian Monsoon, constitutes a critical element of the global climate system. However, a significant climatic-environmental divergence exists between Central and East Asia, which has become increasingly prominent in recent years, highlighting the need to investigate its past evolution. Here, we trace the orbital-scale spatiotemporal evolution of the climate-environment in Central and East Asia since the Late Pliocene, based on high-resolution spectral parameters and geochemical data from a deep core in the Tibetan Plateau, and a compilation of multiple paleoclimate records from both regions. The results indicate a marked climatic divergence between the two regions since ca. 2 Ma, characterized by synchronously increased precipitation in East Asia and enhanced aridification in Central Asia. We attribute this divergence to concurrent expansion of the Antarctic Ice Sheet. The resulting Southern Hemisphere cooling created an atmospheric energy deficit, dynamically forcing monsoon precipitation northward into East Asia. Simultaneously, this expansion weakened the Atlantic Meridional Overturning Circulation, steepening the North Atlantic meridional temperature gradient and shifting the Northern Hemisphere Westerlies southward to divert moisture away from Central Asia, thereby exacerbating aridity there ca. 1.2 Ma. A consistent shift in dominant periodicity occurred in records of both regions, transitioning from the previous ∼400 k.y. forcing to a co-dominance of ∼400 k.y., ∼100 k.y., ∼41 k.y., and ∼21 k.y. cycles. This shift suggests enhanced sensitivity of Asian climate to orbital forcing since 1.2 Ma, potentially due to reduced climate stability caused by high-latitude ice expansion.