CO2 levels were much higher in the past. Flora thrived, Fauna thrived. World was a warmer, wetter place. But that was long ago, things will be getting cooler from now on, as they have been for eons. The thought that man can affect this sytem to any extent is brilliance or sheer folly.
I have read that a recent substantial reduction in sunspots on the sun will likely lead to much colder temperatures on earth.
The activities of man on earth are of little consequence compared to natural forces.