I am out of my knowledge comfort zone (again!) by speculating this but I believe the CO2 used in soda came from the atmosphere so putting it back means the entire process is not part of the carbon cycle and thus has no effect on the amount of greenhouse gasses.

THe CO2 from carbonated drinks is not having an effect because no fossil fuels are burned to create the CO2 used in the process. One could make the claim that the bottling process and distribution makes use of fossil fuels, but the CO2 released by drinking your Coke, has no effect.

Amazingly, Raisin and Mike actually have the right answer.

It's either taken from the air (in which case it's its own mini carbon cycle, being taken from the air, then released back into it) or derived from biological sources (in which case it's just part of the *regular* carbon cycle, being diverted to unusual purposes). I'm not 100% sure which. I think it may be taken from the air for soda, and derived from yeast for alcoholic beverages.

The CO2 put into soft drinks is sourced from other processes. It is recycled.

yes

And is this made just for this purpose or used from a waste product? There must be millions of cans/bottles releasing this in to the atmosphere every year adding to the greenhouse effect?