Maybe it’s just a concept, a construct for other future actions. But can insignificant man really dent the CO2 levels in the atmosphere and seas through wholly artificial means? Some of the proposals are valid (pumping CO2-rich water into limestone formations among others). But all methods look crazy expensive compared to just nudging mother nature.
How much better are the methods of artificially trapping CO2 compared with, say, planting or just leaving thousands of hectares of land to forest? A three-foot diameter tree must store more than a tonne of carbon. Or how about just protecting swamps and marsh land to allow the black goo to accumulate en route to becoming lignite and coal?