Together with the latent heat stored in glacial ice sheets, the ocean heat uptake carries the lion's share of glacial–interglacial changes in the planetary heat content, but little direct information on the global mean ocean temperature (MOT) is available to constrain the ocean temperature response to glacial–interglacial climate perturbations. Using ratios of noble gases and molecular nitrogen trapped in the Antarctic EPICA Dome C ice core, we are able to reconstruct MOT for peak glacial and interglacial conditions during the last 700 000 years and explore the differences between these extrema. To this end, we have to correct the noble gas ratios for gas transport effects in the firn column and gas loss fractionation processes of the samples after ice core retrieval using the full elemental matrix of N₂, Ar, Kr, and Xe in the ice and their individual isotopic ratios. The reconstructed MOT in peak glacials is consistently about 3.3 ± 0.4 ^∘C cooler compared to the Holocene. Lukewarm interglacials before the Mid-Brunhes Event 450 kyr ago are characterized by 1.6 ± 0.4 ^∘C lower MOT than the Holocene; thus, glacial–interglacial amplitudes were only about 50 % of those after the Mid-Brunhes Event, in line with the reduced radiative forcing by lower greenhouse gas concentrations and their Earth system feedbacks. Moreover, we find significantly increased MOTs at the onset of Marine Isotope Stage 5.5 and 9.3, which are coeval with CO₂ and CH₄ overshoots at that time. We link these CO₂ and CH₄ overshoots to a resumption of the Atlantic Meridional Overturning Circulation, which is also the starting point of the release of heat previously accumulated in the ocean during times of reduced overturning.

中文翻译：

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使用EPICA Dome C冰芯中的稀有气体捕获的过去70万年的平均海洋温度快照

连同储存在冰川冰盖中的潜热一起，海洋热量的吸收在行星热量含量中占冰河间变化的最大份额，但是鲜有关于全球平均海洋温度（MOT）的直接信息可用来限制海洋温度。对冰川-冰川间气候扰动的反应。利用南极EPICA Dome C冰芯中捕获的稀有气体和分子氮的比率，我们能够重建过去70万年来冰川和冰间条件峰值的MOT，并探索这些极端之间的差异。为此，我们必须使用N ₂的完整元素矩阵来校正稀有气体比率，以解决在焙烧塔中的气体传输影响和样品在冰芯取回后样品的气体损失损失分离过程中的惰性气体比率。冰中的Ar，Kr和Xe及其各自的同位素比率。在峰冰期重构MOT是一贯约3.3  ±  0.4  ^∘ Ç冷却器相比全新世。中部布容事件450 KYR前的特征在于前温间冰期1.6  ±  0.4  ^∘ C下部MOT比全新世; 因此，冰川间的振幅仅是中等爆发事件后的50％，这与较低温室气体浓度及其地球系统反馈导致的辐射强迫降低有关。此外，我们发现海洋同位素阶段5.5和9.3开始时的MOT显着增加，这与当时的CO ₂和CH ₄过冲同时发生。我们将这些CO链接起来₂和CH _4会超调，以恢复大西洋子午倾覆环流，这也是先前在减少倾覆时释放在海洋中的热量释放的起点。