Would reducing the amount of CO2 in the atmosphere reverse current problems? On it's own, it would start to, yes. It would reduce global temperatures, reduce weather irregularities, begin to cool the globe back down.
But we'd then have to move on to other things like deforestation, overfishing, water conflicts, plastics, etc. It's not a panacea, but it would reverse course on a pretty significant root cause.
Just because we should have started something 30+ years ago isn't a reason to not do it today.
I should have started going to the gym before, I'd be healthier today. I guess I'll just never go to the gym. I should have been eating heather food before I got diabetes and high blood pressure. I guess I'll just keep having a terrible diet. Same kind of logic.