Could it be that no matter what is done, CO2 is still less than .04% of the air we breathe. This whole idea of capturing CO2 is like trying to capture a 'will o' the wisp' which doesn't even exist. Or like trying to actually spot a sasquach.
CO2 is captured by plants but that requires enormous amounts of energy. Manmade CO2 can be captured "more easily" because it is captured at the exhaust pipe at much higher concentrations. Still hard but not nearly as hard. If man tried to pull some of the 0.04% from the air, that would be prohibitive in terms of energy, and pointless in terms of earth science.