The only period in 600 million years when CO2 levels were equal to the present was over 300 million years ago. Since that time CO2 levels averaged 1000 to 1200 ppm or 3 to 4 times current levels. How did the plant and animal life survive those levels? It makes a mockery of the claim that even a doubling of atmospheric CO2 is a problem.
Fallacy: false equivalence