Context to your context:
https://earth.org/data_visualization/a-brief-history-of-co2/
There is no realistic way that in the near future we could fall below 200ppm, since we are at over 400 and rising faster then ever encountered, since the existance of time. 

And the climateffect of CO2 is this easy to understand, there is no doubt about it that higher concentration leads to global warming of our atmosphere.