Midlatitude Asia (MLA), strongly influenced by westerlies-controlled climate, is a key source of global atmospheric dust, and plays a significant role in Earth’s climate system . However, it remains unclear how the westerlies, MLA aridity, and dust flux from this region evolved over time. Here, we report a unique high-resolution eolian dust record covering the past 3.6 Ma, retrieved from the thickest loess borehole sequence (671 m) recovered to date, at the southern margin of the Taklimakan desert in the MLA interior. The results show that eolian dust accumulation, which is closely related to aridity and the westerlies, indicates existence of a dry climate, desert area, and stable land surface, promoting continuous loess deposition since at least ∼3.6 Ma. This region experienced long-term stepwise drying at ∼2.7, 1.1, and 0.5 Ma, coeval with a dominant periodicity shift from 41-ka cyclicity to 100-ka cyclicity between 1.1 Ma and 0.5 Ma. These features match well with global ice volume variability both in the time and frequency domains (including the Mid-Pleistocene Transition), highlighting global cooling-forced aridity and westerlies climate changes on these timescales. Numerical modeling demonstrates that global cooling can dry MLA and intensify the westerlies, which facilitates dust emission and transport, providing an interpretive framework. Increased dust may have promoted positive feedbacks (e.g., decreasing atmospheric CO₂ concentrations and modulating radiation budgets), contributing to further cooling. Unraveling the long-term evolution of MLA aridity and westerlies climate is an indispensable component of the unfolding mystery of global climate change.

中纬度亚洲（MLA）受西风控制气候的强烈影响，是全球大气尘埃的重要来源，并且在地球气候系统中起着重要作用。但是，目前尚不清楚该地区的西风，MLA干旱和粉尘通量如何随时间演变。在这里，我们报告了一个独特的高分辨率风尘记录，覆盖了过去3.6 Ma，该数据是从MLA内部塔克拉玛干沙漠南缘的迄今为止最厚的黄土钻孔序列（671 m）中获得的。结果表明，与干旱和西风密切相关的风沙尘埃堆积表明存在干旱的气候，沙漠地区和稳定的地表，从至少〜3.6 Ma开始促进了连续的黄土沉积。该区域在2.7、1.1和0.5 Ma处经历了长期的逐步干燥，周期具有显着的周期性，在1.1 Ma和0.5 Ma之间从41-ka周期性转变为100-ka周期性。这些特征与时域和频域（包括中更新世过渡）中全球冰量的变化非常吻合，突显了全球冷却强迫干旱和这些时间尺度上的西风气候变化。数值模拟表明，整体冷却可以使MLA干燥并使西风变强，这有利于粉尘的排放和运输，提供了解释性的框架。增加的粉尘可能促进了积极的反馈（例如，减少大气中的CO 在这些时间尺度上重点介绍了全球降温造成的干旱，并对气候变化进行了西风处理。数值模拟表明，整体冷却可以使MLA干燥并使西风变强，这有利于粉尘的排放和运输，提供了解释性的框架。增加的粉尘可能促进了积极的反馈（例如，减少大气中的CO 在这些时间尺度上重点介绍了全球降温造成的干旱，并对气候变化进行了西风处理。数值模拟表明，整体冷却可以使MLA干燥并使西风变强，这有利于粉尘的排放和运输，提供了解释性的框架。增加的粉尘可能促进了积极的反馈（例如，减少大气中的CO₂浓度和调制辐射预算），有助于进一步冷却。揭开MLA干旱和西风气候的长期演变，是全球气候变化谜团不可或缺的组成部分。