Abstract. Deglaciations are characterized by the largest natural changes in methane (CH₄) and nitrous oxide (N₂O) concentrations of the past 800 thousand years. Reconstructions of millennial to centennial-scale variability within these periods are mostly restricted to the last deglaciation. In this study, we present composite records of CH₄ and N₂O concentrations from the EPICA Dome C ice core covering the penultimate deglaciation at temporal resolutions of about ~ 100 years. Our data permit the identification of centennial-scale fluctuations standing out of the overall transition to interglacial levels. These features occurred in concert with reinvigorations of the Atlantic Meridional Overturning Circulation (AMOC) and northward shifts of the Intertropical Convergence Zone. The abrupt CH₄ and N₂O rises at about ~ 134 and ~ 128 thousand of years before present (hereafter ka BP) are assimilated to the fluctuations accompanying the Dansgaard–Oeschger events of the last glacial period, while rising N₂O levels at ~ 130.5 ka BP are assimilated to a pattern of increasing N₂O concentrations that characterized the end of Heinrich stadials. We suggest the 130.5-ka event to be driven by a partial reinvigoration of the AMOC. Overall, the CH₄ and N₂O fluctuations during the penultimate deglaciation exhibit modes of variability that are also found during the last deglaciation. However, trace gas responses may differ for similar type of climatic events, as exemplified by the reduced amplitude and duration of the 134-ka event compared to the fluctuations of the Bølling–Allerød during the last deglaciation.

中文翻译：

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倒数第二次冰消期间CH ₄和N ₂ O的波动

摘要。冰川融化的特征是过去80万年来甲烷（CH ₄）和一氧化二氮（N ₂ O）浓度最大的自然变化。在这些时期内，千年至百年尺度变化的重构主要限于最后一次冰消。在这项研究中，我们介绍了CH ₄和N _2的复合记录来自EPICA Dome C冰芯的O浓度以约100年的时间分辨率覆盖了倒数第二个脱冰。我们的数据可以识别出从总体过渡到冰期之间的百年尺度波动。这些特征与大西洋子午翻转环流（AMOC）的复兴和热带辐合带的北移同时发生。CH ₄和N ₂ O的突然升高大约在目前的134年和〜12.8万年前（此后称为ka BP）与上一次冰川期伴随的Dansgaard-Oeschger事件的波动同化，而N ₂ O的水平在〜130.5 ka BP被同化为N ₂增加的模式以Heinrich球茎末端为特征的O浓度。我们建议将130.5-ka事件归功于AMOC的部分复兴。总的来说，倒数第二个脱冰过程中的CH ₄和N ₂ O波动表现出变化的模式，在最后一次脱冰过程中也发现了这种模式。但是，对于类似类型的气候事件，痕量气体的响应可能会有所不同，例如，与最后一次冰消冰期中Bølling-Allerød的波动相比，134-ka事件的幅度和持续时间减小了。