Grains (Score 5, Informative)

Alcohol is made from breaking down grains or other starches. Those plants gather CO2 from the air. So the consumption of alcohol doesn't really add to the problem. That is, at least only to the extent that agriculture does. If you're really worried about CO2 related to your food/beverage intake, you should cut back on meat, which has 8x-10x as much of a carbon footprint per calorie than grains. I guess alcohol would be somewhere in between.