Maybe it's not clear that I'm talking about what to do with the excess CO₂ after we've stopped emitting more!

The stratospheric injections of SO₂ can bring temperatures down to healthy levels. This fixes most of the negative effects of high CO₂, and can go on for centuries if need be...

... but I'd prefer to get that CO₂ out once and for all. Solar powered machines that extracts it from the air and pumps it down to eternal underground cavities should be able to do that once we have much better tech. If it takes decades or centuries doesn't matter too much.