But don't forget--CO2 is allegedly a dangerous pollutant

SOOBF Sapporo to market beer with 'carbon footprint' labels on cans

Sapporo Breweries Ltd. said Thursday it will start test sales of beer with "carbon footprint" labels on cans in Hokkaido next month in a bid to contribute to efforts to combat global warming.

All About Beer Features: It's a Gas!

Today, commercial beers generally contain a fairly consistent amount of carbonation. Among brewers, the extent of carbonation is usually specified in "volumes of CO2." Brewers would say that the average American beer contains about 2.5 volumes of CO2. Now here's what that means to the beer drinker: the CO2 dissolved in one pint of beer would fill two and one-half pint glasses. Seen another way, the beer in a standard 12-ounce bottle contains enough CO2 to fill a 16-inch softball.

That seems like a lot of gas, doesn't it?
...
...fermented beer nearly always requires an additional dose of carbonation before it is packaged. To do this, brewers have two choices.

On the one hand, they can put the beer in a closed pressure tank, hook up a bottle of carbon dioxide, and pump a bunch in. Using pressure gauges and perhaps some simple testing equipment, they can determine exactly when the beer contains the desired level of carbonation. Most breweries use this technique because it is cheap, easy and fast.

The second choice relies on more traditional methods. Rather than adding carbon dioxide directly, brewers can add a measured amount of unfermented beer (called wort) along with some yeast. The yeast ferments the wort to produce additional CO2. As long as the beer is stored in a pressure-tight container (keg, bottle or serving tank), during this phase, the newly produced gas will dissolve in the beer.

10/07/92 How is soda pop carbonated?

There are three main ingredients in soda pop: water, syrup and carbon dioxide gas. It is the carbon dioxide gas that is responsible for the fizziness...The ingredients are mixed in a container and the empty space at the top of the container is filled with carbon dioxide gas.