Role of land-ocean interactions in stepwise Northern Hemisphere Glaciation

The investigation of triggers causing the onset and intensification of Northern Hemisphere Glaciation (NHG) during the late Pliocene is essential for understanding the global climate system, with important implications for projecting future climate changes. Despite their critical roles in the global climate system, influences of land-ocean interactions on high-latitude ice sheets remain largely unexplored. Here, we present a new high-resolution Asian dust record from Ocean Drilling Program Site 1208 in the North Pacific, which lies along the main route of the westerlies. Our data indicate that atmosphere-land-ocean interactions affected aeolian dust emissions through modulating moisture and vegetation in dust source regions, highlighting a critical role of terrestrial systems in initiating the NHG as early as 3.6 Myr ago. Combined with additional multi-proxy and model results, we further show that westerly wind strength was enhanced, mainly at low-to-middle tropospheric levels, during major glacial events at about 3.3 and 2.7 Myr ago. We suggest that coupled responses of Earth’s surface dynamics and atmospheric circulation in the Plio-Pleistocene likely involved feedbacks related to changes in paleogeography, ocean circulation, and global climate.对上新世晚期北半球冰期（Northern Hemisphere Glaciation，简称NHG）的启动与加剧触发机制开展研究，是理解全球气候系统的关键所在，对未来气候变化的预测亦具有重要参考价值。尽管海陆相互作用在全球气候系统中发挥着关键作用，但目前学界对其影响高纬度冰盖的机制仍鲜有探索。本研究依托位于北太平洋西风带主通道上的大洋钻探计划（Ocean Drilling Program）1208站位，首次发布一套高分辨率亚洲风尘记录。研究数据表明，气-陆-海相互作用通过调控沙尘源区的水汽条件与植被状态，进而影响风尘排放，这一结果凸显了陆地系统早在360万年前就对北半球冰期的启动起到了关键作用。结合额外的多代用指标与数值模拟结果，本研究进一步发现，在约330万与270万年前的主要冰期事件中，对流层中低层的西风强度显著增强。我们提出，上新世-更新世（Plio-Pleistocene）时期地球表层动力学与大气环流的耦合响应，可能涉及与古地理、海洋环流及全球气候变化相关的反馈机制。