Eh, CO2 is a pretty low energy molecule so doing anything with it usually takes energy input. I'd believe in a ton of other wacky sci-fi ideas turning into real

Eh, CO2 is a pretty low energy molecule so doing anything with it usually takes energy input. I'd believe in a ton of other wacky sci-fi ideas turning into reality before that one. That said, I'm hopeful we could use cheap energy (e.g. the sun) to do something useful with carbon in the air, like plants do. See Running Tide as an example, they're trying to sequester carbon in a completely hands-off way using no added energy input other than the sun.