What about other animals, they don't improve their technollogy so every time there are less species in the earth, maybe humans can survive but I thing we should take care of the other live beings.
Maybe plants absorb Co2 faster when there's more of it, but isn't there a limit to?
Also in order to absorb more, plants produce less protein and zinc so we would need some other way to supply humans from these essential things.

In conclusion global warming will be bad for earth's biodiversity.