Using new and previously published CO₂ data from the EPICA Dome C ice core (EDC), we reconstruct a new high-resolution record of atmospheric CO₂ during Marine Isotope Stage (MIS) 6 (190 to 135 ka) the penultimate glacial period. Similar to the last glacial cycle, where high-resolution data already exists, our record shows that during longer North Atlantic (NA) stadials, millennial CO₂ variations during MIS 6 are clearly coincident with the bipolar seesaw signal in the Antarctic temperature record. However, during one short stadial in the NA, atmospheric CO₂ variation is small (∼5 ppm) and the relationship between temperature variations in EDC and atmospheric CO₂ is unclear. The magnitude of CO₂ increase during Carbon Dioxide Maxima (CDM) is closely related to the NA stadial duration in both MIS 6 and MIS 3 (60–27 ka). This observation implies that during the last two glacials the overall bipolar seesaw coupling of climate and atmospheric CO₂ operated similarly. In addition, similar to the last glacial period, CDM during the earliest MIS 6 show different lags with respect to the corresponding abrupt CH₄ rises, the latter reflecting rapid warming in the Northern Hemisphere (NH). During MIS 6i at around 181.5±0.3 ka, CDM 6i lags the abrupt warming in the NH by only 240±320 years. However, during CDM 6iv (171.1±0.2 ka) and CDM 6iii (175.4±0.4 ka) the lag is much longer: 1290±540 years on average. We speculate that the size of this lag may be related to a larger expansion of carbon-rich, southern-sourced waters into the Northern Hemisphere in MIS 6, providing a larger carbon reservoir that requires more time to be depleted.

中文翻译：

---

海洋同位素第6阶段（190–135 ka）的千年尺度大气CO ₂变化

使用来自EPICA圆顶C冰芯（EDC）的新的和先前发布的CO ₂数据，我们重建了倒数第二个冰期海洋同位素阶段（MIS）6（190至135 ka）期间大气CO ₂的新高分辨率记录。与已经存在高分辨率数据的上一个冰川周期相似，我们的记录显示，在更长的北大西洋（NA）球场中，MIS 6期间千禧年CO _2的变化明显与南极温度记录中的双极跷跷板信号一致。但是，在北大西洋一个短暂的静止期，大气中的 CO ₂变化很小（〜5 ppm）和EDC中的温度变化与大气CO ₂之间的关系尚不清楚。二氧化碳最大值（CDM）期间CO _2的增加幅度与MIS 6和MIS 3（60–27 ka）中的NA持续时间密切相关。该观察结果暗示，在最后两个冰川期间，气候和大气CO ₂的整体双极跷跷板耦合作用相似。此外，类似于最后一个冰川期，最早的MIS 6期间的CDM相对于相应的CH ₄突然上升显示出不同的滞后 ，后者反映了北半球（NH）的快速变暖。在MIS 6i期间约为181.5±0.3 ka，CDM 6i仅比NH的突然变暖滞后240± 320年。但是，在CDM 6iv（171.1± 0.2 ka）和CDM 6iii（175.4± 0.4 ka）期间，滞后时间更长：平均为1290± 540年。我们推测，这种滞后现象的大小可能与MIS 6中富含碳的南方来源的水向北半球的更大扩张有关，从而提供了一个更大的碳库，需要更多的时间来消耗掉。