Check out the following:

nature.com

This graph from Luthi, et al in Nature, May, 2008, clearly shows levels of CO2 higher than today at ~318,000 years ago. At cores dating to ~110,000 years ago, 240,000, and 400,000 years ago, levels were not significantly different than they are today. I do not think that this cyclical change shown not only in this ice core data, but by others from other sites, had anything to do with humankind. The corresponding temperature anomalies are at times higher than today’s. This is Science with a capital S. I am not a denier. I have no dog in this fight, except the truth should matter, even to those zealously committed to phony science when the real science totally unmasks what the “majority” spokespeople for scientific organizations are espousing.