The development of larger and longer‐lasting northern hemisphere ice sheets during the Mid Pleistocene Transition (MPT) coincided with global cooling. Here we show that surface waters of the north‐eastern Atlantic actually warmed across this interval (∼1.2‐0.8Ma), which we argue reflects an increase in the north‐eastward transport of heat and moisture via the North Atlantic Current (NAC) into the Nordic Seas (the Atlantic Inflow). We suggest that simultaneous cooling and warming along the north‐western and south‐eastern margins (respectively) of the NAC during Marine Isotope Stage 28 (∼995ka) reflected the increasing persistence of northern ice sheets as Atlantic Inflow increased. This resulted in a diachronous shift from ∼40kyr to ∼100kyr cyclicity across the NE Atlantic as the growing influence of northern ice sheets spread southwards; to the north‐west of the NAC the first ‘100kyr’ cycle preceded Termination 12 (∼960ka) while on the south‐eastern margin of the NAC the transition occurred ∼100kyr later. Exploratory climate model simulations suggest that increasing Atlantic Inflow at this time could have accelerated ice sheet growth because pre‐existing moderately sized ice sheets allowed the positive effect of increasing precipitation to outpace melting. In addition, we propose that the dependence of post‐MPT ice sheets on moisture transport via the Atlantic Inflow may ultimately contribute to their apparent vulnerability to insolation forcing once a critical size threshold is crossed and high latitude ice sheets become starved of a vital moisture source.

中文翻译：

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在整个中更新世过渡期间加强大西洋的流入

中更新世过渡期（MPT）期间北半球更大，更持久的冰盖的形成与全球降温相吻合。在这里，我们表明东北大西洋的地表水实际上在此时间间隔内变暖（约1.2-0.8Ma），我们认为这反映了热量和水分通过北大西洋海流（NAC）向东北的向东北输送增加。北欧海（大西洋流入）。我们建议，在海洋同位素阶段28（〜995ka）期间，NAC西北边缘和东南边缘的分别冷却和变暖同时反映出北大西洋冰盖层的持久性随着大西洋入海量的增加而增加。随着北部冰原向南扩展的影响，整个东北大西洋从约40kyr到约100kyr的周期性转变。在NAC的西北部，第一个“ 100kyr”周期先于12号终端（约960ka），而在NAC的东南边缘，过渡发生在约100kyr之后。探索性的气候模型模拟表明，此时增加的大西洋流入量可能会加速冰盖的生长，因为预先存在的中等大小的冰盖可以使降水增加的积极作用超过融化。此外，我们建议，一旦超过临界尺寸阈值并且高纬度冰盖饿死了重要的水分源，MPT后冰盖对通过大西洋流入的水分传输的依赖性可能最终导致其明显受到日照强迫的脆弱性。