Centennial-scale increases of atmospheric carbon dioxide, known as carbon dioxide jumps, are identified during deglacial, glacial and interglacial periods and linked to the Northern Hemisphere abrupt climate variations. However, the limited number of identified carbon dioxide jumps prevents investigating the role of orbital background conditions on the different components of the global carbon cycle that may lead to such rapid atmospheric carbon dioxide releases. Here we present a high-resolution carbon dioxide record measured on an Antarctic ice core between 260,000 and 190,000 years ago, which reveals seven additional carbon dioxide Jumps. Eighteen of the 22 jumps identified over the past 500,000 years occurred under a context of high obliquity. Simulations performed with an Earth system model of intermediate complexity point towards both the Southern Ocean and the continental biosphere as the two main carbon sources during carbon dioxide jumps connected to Heinrich ice rafting events. Notably, the continental biosphere appears as the obliquity-dependent carbon dioxide source for these abrupt events. We demonstrate that the orbital-scale external forcing directly impacts past abrupt atmospheric carbon dioxide changes.

大气中二氧化碳的百年期增加，称为二氧化碳跃迁，是在冰期、冰期和间冰期确定的，并与北半球的气候突变有关。然而，已确定的二氧化碳跳跃数量有限，因此无法研究轨道背景条件对全球碳循环不同组成部分的作用，这可能导致大气中二氧化碳如此快速的释放。在这里，我们展示了 260,000 至 190,000 年前在南极冰芯上测量的高分辨率二氧化碳记录，其中揭示了另外 7 次二氧化碳跳跃。在过去 500,000 年中发现的 22 次跳跃中，有 18 次发生在高度倾斜的背景下。使用中等复杂度的地球系统模型进行的模拟表明，南大洋和大陆生物圈是与海因里希冰上漂流活动相关的二氧化碳跳跃期间的两个主要碳源。值得注意的是，大陆生物圈似乎是这些突然事件的倾斜依赖性二氧化碳来源。我们证明了轨道尺度的外部强迫直接影响过去的大气二氧化碳突变。