CO2 is not a driver of climate. Climate changes constantly. There is no long-term correlation between rises in CO2 and subsequent rises in globally averaged temperatures.
CO2 is vital for all life on earth. At levels below 300 ppm, plant growth and productivity begins to be severely impaired. Optimum levels for plant growth seems to be about 1000ppm. This is the level greenhouse operators aim for to give maximum growth and yields. Humans and other animals cope easily with levels as high as 4,000 ppm. Our exhaled breath contains as much as 35,00ppm and is safely used for CPR.