Sure. As if CO2 were the limiting factor in photosynthesis, which it isn't. But that's OK, because they don't really care about being right. They'll just shift on to the next argument, even if it's contradictory to the ones they're already using. That's how a Gish Gallop works.

You can just point them at https://skepticalscience.com/oneliners.php for a lengthy list of the arguments they're going to use and the trivial reasons why they're wrong, but it doesn't get at the core of the problem: you can't reason somebody out of a place they didn't reason themselves into.