(Fig. 1D, 3E) Sea surface temperature and alkenone C37:4 for sediment core MD01-2444 during the penultimate glaciation@en

Past glacials can be thought of as natural experiments in which variations in boundary conditions influenced the character of climate change. However, beyond the last glacial, an integrated view of orbital- and millennial-scale changes and their relation to the record of glaciation has been lacking. Here, we present a detailed record of variations in the land-ocean system from the Portuguese margin during the penultimate glacial and place it within the framework of ice-volume changes, with particular reference to European ice-sheet dynamics. The interaction of orbital- and millennial-scale variability divides the glacial into an early part with warmer and wetter overall conditions and prominent climate oscillations, a transitional mid-part, and a late part with more subdued changes as the system entered a maximum glacial state. The most extreme event occurred in the mid-part and was associated with melting of the extensive European ice sheet and maximum discharge from the Fleuve Manche river. This led to disruption of the meridional overturning circulation, but not a major activation of the bipolar seesaw. In addition to stadial duration, magnitude of freshwater forcing, and background climate, the evidence also points to the influence of the location of freshwater discharges on the extent of interhemispheric heat transport.古冰期可被视作天然气候实验，其边界条件的变化直接调控着气候变化的特征。然而，针对末次冰期之前的轨道尺度（orbital-scale）与千年尺度（millennial-scale）气候变化及其与冰期记录的关联，学界始终缺乏系统性的综合认知。本文基于葡萄牙陆缘的沉积记录，重建了倒数第二次冰期期间陆海系统的详细变化序列，并将其纳入冰量变化的研究框架，重点探讨欧洲冰盖的动力学机制。轨道尺度与千年尺度变率的相互作用，将该冰期划分为三个阶段：早冰期阶段整体暖湿且伴随显著气候振荡，中冰期为过渡阶段，晚冰期阶段则随着系统进入冰盛期状态，气候变化幅度趋于平缓。该冰期最极端的事件发生于中冰期阶段，与大规模欧洲冰盖消融以及Fleuve Manche河的最大径流量事件密切相关。该事件引发了经向翻转环流（meridional overturning circulation）的中断，但并未导致双极跷跷板的显著激活。除冰阶（stadial）持续时长、淡水强迫强度与背景气候状态外，研究证据还表明，淡水排放的位置同样会影响跨半球热输送的规模。