Minerals aside, Helium-3 will probably be the most important article on the list of economically feasible things to mine on Moon and carry all the way back to Earth. It'll take a long long time before mineral depletion on Earth's surface crust becomes serious enough that it starts to become feasible to mine Moon or asteroids... eventually, yes, but not in a long while as far as I see it.
Of course, even better would be to have the He-3 based fusion reactors running on Moon's surface and transfer the energy to Earth via lasers or some other as of now unknown method of energy transfer.
Transferring CO2 to the moon isn't really that good an idea, never mind being any kind of solution to the CO2 problem... better would be to make the lunar facility use completely or at least nearly self-sustainable carbon cycle.