During the last glacial period, atmospheric carbon dioxide (CO₂) closely followed Antarctic temperature on millennial timescales. This strong correlation between Antarctic climate and atmospheric CO₂ has led to suggestions that reorganizations of Southern Ocean circulation and/or biogeochemistry were the dominant cause of these variations. However, recent work also revealed centennial-scale changes in CO₂ that appear unrelated to Antarctic climate and may represent additional modes of carbon cycle variability. Here we present a high-resolution CO₂ record from the last glacial period from an ice core drilled in West Antarctica. This reconstruction precisely defines the timing of millennial and centennial CO₂ variations with respect to Antarctic temperature and abrupt changes in Northern Hemisphere climate during Heinrich stadials and Dansgaard–Oeschger events. On the millennial scale, CO₂ tracks Antarctic climate variability, but peak CO₂ levels lag peak Antarctic temperature by more than 500 years. Centennial-scale CO₂ increases of up to 10 ppm occurred within some Heinrich stadials, and increases of ~5 ppm occurred at the abrupt warming of most Dansgaard–Oeschger events. Regression analysis suggests that the CO₂ variations can be explained by a combination of one mechanism operating on the timescale of Antarctic climate variability and a second responding on the timescale of Dansgaard–Oeschger events. Consistent with our statistical analysis, carbon cycle box-model simulations illustrate a plausible scenario where Southern Hemisphere processes contribute the majority of the CO₂ variability during the last glacial period, but Northern Hemisphere processes are the crucial drivers of centennial-scale variability.

在最后一个冰河时期，大气中的二氧化碳（CO ₂）在千年时间尺度上紧随南极温度。南极气候和大气 CO ₂之间的这种强相关性导致人们认为南大洋环流和/或生物地球化学的重组是这些变化的主要原因。_{然而，最近的工作也揭示了 CO 2}的百年尺度变化，这些变化似乎与南极气候无关，可能代表了碳循环变异的其他模式。在这里，我们展示了在南极洲西部钻探的冰芯中最后一次冰期的高分辨率 CO _2记录。这种重建精确地定义了千禧年和百年CO _2的时间Heinrich stadials 和 Dansgaard-Oeschger 事件期间南极温度的变化和北半球气候的突然变化。在千年尺度上，CO ₂跟踪南极气候变化，但峰值 CO ₂水平滞后于南极温度峰值 500 多年。在一些 Heinrich stadials 中发生了高达 10 ppm 的百年尺度 CO ₂增加，而在大多数 Dansgaard-Oeschger 事件突然变暖时增加了约 5 ppm。回归分析表明，CO ₂变化可以通过在南极气候变率时间尺度上运行的一种机制和在 Dansgaard-Oeschger 事件时间尺度上的第二种响应相结合来解释。与我们的统计分析一致，碳循环箱模型模拟说明了一个似是而非的情景，即南半球过程贡献了末次冰期 CO ₂变化的大部分，但北半球过程是百年尺度变化的关键驱动因素。