It has been a long known fact that higher CO2 concentrations improve the growth of plants. Most greenhouses in NL get CO2 supplied from the harbor of Rotterdam. Anyway salt water infiltration will also kill a lot of plant life and floodings will cause the soils to cause more salt. And salt isn't exactly a thing most plant species endure very well.

Anywho as other said CO2 also causes oceans to accidify which causes corals to bleach and nearly a third off al fish species need coral to survive. Also the exo skeletons of shell fish and krill are desolving because of this acidification. So if anything climate change will rather cause the 6th mass extinction than a new bloom of life.

So the only sector really happy with this are farmers and companies that cultivate wood for furniture.

Please excuse my (probally) poor grammar