CO2 peaks and “past civilizations”

As the most abundant greenhouse gas in our atmosphere, CO2 levels have varied widely over the course of the Earth’s 4.54 billion year history.

Source: A Graphical History of Atmospheric CO2 Levels Over Time | Earth.Org – Past | Present | Future

Some people could hypotize that there have been three or four “industrial civilizations” before us in the last million years… look at the sudden peaks in CO2 concentrations in the Pleistocene. Those peaks are of the same order of magnitute of the current one… but the time scale is not the same…