/sci/ - Science & Math

It's a phenomenon called band saturation. Learn more here
forecast.uchicago.edu/chapter4.pdf

Once CO2 is high enough, there's diminishing effect on its warming effect. Most of earth's history CO2 is beyond 1000 ppm, which means that the absorption band is always saturated and earth's temperature is controlled by factors other than CO2.

However, since the quarternary, around 3 million years ago, and especially the last 800ky when we have ice core records CO2 have been in goldilocks zone where it is low enough to not have its absorption band saturated but high enough to have control on the climate