Fig. 2: Glacial and interglacial evolution of atmospheric CO₂ and global climate.

All the records were separated into glacial (a–e on the left) and interglacial (f–j on the right) subsets and binned to a 0.3-million-year (300-ky) time window. CO₂ data beyond 800 ka were compiled paleosol- and boron-based estimates^{9,10,14,15,16,17,49} and blue-ice measurements^12,78. The medians are highlighted by horizontal lines. Gray dashed lines connect the maximum and minimum values of each time window. The long-term decline in glacial CO₂, along with the relatively stable interglacial CO₂ maxima, is broadly consistent with global temperature trends.