[cogman10]

Here's what a university has to say on the matter [1]

The gist of it, CO2 supplementation can be beneficial to some plants (not all plants) IFF you also tweak all other inputs into growth. Not something that happens outside of a greenhouse.

> Plants may not show a positive response to supplemental CO2 because of other limiting factors such as nutrients, water and light. All factors need to be at optimum levels.

[1] https://extension.okstate.edu/fact-sheets/greenhouse-carbon-...

[ETH_start]

Well, plant growth on Earth massively increased in the 30 years up to the 2016 study. It would be quite the coincidence that it stopped right after that study.