claim: The killer proof that CO2 does not drive climate is to be found during the Ordovician- Silurian and the Jurassic-Cretaceous periods when CO2 levels were greater than 4000 ppmv ( parts per million by volume ) and about 2000 ppmv respectively.
evidence: The Triassic (  / traɪˈæs.ɪk /  try-ASS-ik ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.9 million years ago ( Mya ), to the beginning of the Jurassic Period 201.3 Mya.