The average American drinks 54 gallons of sodapop every year. So at a conservative estimate that's 100 million Americans therefore 5.4 billion gallons. So the question is, how much CO2 is in your average gallon of soda? There .. oh wait, I'm not the first person to have this brain fart.. Ecogeek beat me to it.
So his estimate, which is three times less conservative than I was going to speculate, is in the neighborhood of 400 kilotons of CO2 farts and belches, unless CO2 is somehow sequestered in the body of the person drinking, which I doubt. Good lord let us hope anyway, because the CO2 we get in soda is a by-product of other industrial processes. Coca-Cola will have us thinking about human sequestration.
Anyway, it turns out that even the generous number is a drop in the greenhouse gas bucket. We're talking US dumps 1.6 Billion Metric Tons of the stuff every year. So go ahead, drink, belch and fart with impunity. Your carbon burpprint is but a trifle.