There’s a very short window where plants improve with more CO2, where they scrub more of it from the atmosphere than usual. This window is apparently overwhelmed in a hurry with the levels we’re seeing, though, resulting in crop die-outs which are exacerbated by warming-influenced droughts.
This would, in a perfect world, shut up those science denialists who admit global warming is happening, but think plants are going to fix it all for us. Considering we’re waging an all-out war on plants to begin with, I fail to see how these people honestly think there’s not a problem. It’s either short-sightedness or wishful thinking that leads people to believe this particular line of anti-AGW bunkum.