Regarding encouraging plant growth, that is a direct CO2 effect. Interestingly, I just learned that it is killing koalas. You see, CO2 fertilized plants put more of their energy into structure. Eucalyptus leaves become harder for present day koalas to digest because they are more fibrous.

The person I heard this from (a world renowned ecologist) suspects that many food plants may become more fibrous and harder to digest. So the CO2 fertilization effect is not obviously a win for us fauna.

In general, rapid change in the environment is bad for niche species and good for pests. That is why the concept of "degraded ecosystem" makes sense.

Now picture ever increasing disruption everywhere...

Image: New Zealand Herald, at the first link above.