> Would the practicality of a "CO2 vent to space" work?
No. The atmosphere is not isolated from space in way that could be addressed by venting (selective or not).
You could in principal isolate CO2 and launch it into space (long-term, that's an oxygen-depletion strategy, but, ignoring the resource requirements, it might be better than building it up in the atmosphere on some time scales), but when you consider the resource (including energy) costs of launching material into space, that's a pretty bad idea, especially given that if you can isolate it, you can sequester it on earth with the same atmospheric effect without launching it into space.
No. The atmosphere is not isolated from space in way that could be addressed by venting (selective or not).
You could in principal isolate CO2 and launch it into space (long-term, that's an oxygen-depletion strategy, but, ignoring the resource requirements, it might be better than building it up in the atmosphere on some time scales), but when you consider the resource (including energy) costs of launching material into space, that's a pretty bad idea, especially given that if you can isolate it, you can sequester it on earth with the same atmospheric effect without launching it into space.