The upper branch of the Atlantic meridional overturning circulation (AMOC) plays a critical role in ocean circulation and climate change, yet its variability during the last glacial period is poorly documented. Here, we investigate the northward‐flowing Glacial Eastern Boundary Current (GEBC) in the North Atlantic, known today as the European Slope Current, and representing the easternmost portion of the upper branch of the AMOC. Based on flow speed and isotopic records, we show that Dansgaard‐Oeschger (D‐O) interstadials (stadials) correspond to a faster (weaker) GEBC during the ∼50–15 ka period. This, by analogy to present‐day conditions, suggests enhanced (reduced) strength of the subpolar gyre and, by extension, of northern‐sourced water production and AMOC during D‐O interstadials (stadials). Concomitant fluctuations of both the GEBC and the European Ice Sheet between ∼30 and 17 ka suggest an active role of the upper branch of AMOC in the poleward transport of heat and freshwater to the northern North Atlantic, with direct impacts on deep water formation and AMOC strength. We explore these ice‐sheet—AMOC interactions and the associated abrupt climate changes over the last glacial period and the last deglaciation.

中文翻译：

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北大西洋冰河东部边界流是冰层的主要驱动力—AMOC相互作用和气候不稳定

大西洋经向翻转环流（AMOC）的上支在海洋环流和气候变化中起着至关重要的作用，但是在最后一次冰川期的变化却鲜有记载。在这里，我们调查了北大西洋北向流动的冰川东部边界流（GEBC），今天称为欧洲斜坡流，它代表了AMOC上部分支的最东端。基于流速和同位素记录，我们表明Dansgaard-Oeschger（D-O）陆间（stadals）对应于大约50-15 ka期间较快的GEBC（较弱）。类似于今天的情况，这表明在D-O陆间（陆续）期间，亚极回旋的强度增强（减小），并由此扩展了北源水生产和AMOC。GEBC和欧洲冰盖的伴随波动在30至17 ka之间，这表明AMOC的上部分支在热量和淡水向北大西洋北部的极向输送中起着积极作用，直接影响深水形成和AMOC力量。我们探索了这些冰盖—AMOC的相互作用以及在最后一个冰期和最后一次冰消作用期间相关的突然的气候变化。