The last glacial cycle began around 116,000 years before present during a period with low incoming solar radiation in Northern Hemisphere summer. Following the glacial inception in North America, the marine sediment record depicts a weakening of the high-latitude ocean overturning circulation and a multi-millennial eastward progression of glaciation across the North Atlantic basin. Modelling studies have shown that reduced solar radiation can initiate inception in North America and Siberia; however, the proximity to the temperate North Atlantic typically precludes ice growth in Scandinavia. Using a coupled Earth-system–ice-sheet model, we show that ice forming in North America may help facilitate glacial expansion in Scandinavia. As large coherent ice masses form and start filling the ocean gateways in the Canadian Archipelago, the transport of comparatively fresh North Pacific and Arctic water through the archipelago is diverted east of Greenland, resulting in a freshening of North Atlantic deep convection regions, sea-ice expansion and a substantial cooling that is sufficient to trigger glacial inception in Scandinavia. This mechanism may also help explain the Younger Dryas cold reversal and the rapid regrowth of the Scandinavian Ice Sheet following several warm events in the last glacial period.

上一次冰河周期开始于距今约 116,000 年的北半球夏季入射太阳辐射低的时期。在北美冰川开始之后，海洋沉积物记录描绘了高纬度海洋倾覆环流的减弱以及横跨北大西洋盆地的冰川作用的千年向东进展。建模研究表明，减少的太阳辐射可以在北美和西伯利亚启动；然而，靠近温带北大西洋通常会阻止斯堪的纳维亚半岛的冰层生长。使用耦合的地球系统 - 冰盖模型，我们表明北美的冰形成可能有助于促进斯堪的纳维亚半岛的冰川扩张。随着大块连贯的冰块形成并开始填充加拿大群岛的海洋门户，相对新鲜的北太平洋和北极海水通过群岛的运输被转移到格陵兰以东，导致北大西洋深层对流区域的清新、海冰扩张和足以引发斯堪的纳维亚半岛冰川开始的大幅降温。这种机制也可能有助于解释新仙女木的冷逆转和斯堪的纳维亚冰盖在最后一个冰期的几次温暖事件后的快速再生。