So i hear that pubs are running out of beer because the brewers cannot get hold of enough carbon dioxide and so are having to cut back production. This raises two questions in my mind.

1) why, as we are being told that global warming is the result of too much carbon being released into the atmosphere in the form of CO2, can there be a shortage of CO2. It really is one of those things that you can pluck out of mid air isn't it??

2) Why do brewers need to acquire CO2 in beer production. As a regular home brewer of the past, I never had to buy CO2. The natural fermentation process created the gas in the beer (albeit a rather flat beer which would not appeal to today's generation of gassy lager drinkers). In fact a lot of the surplus gas created during fermentation used to bubble off, but still produced a reasonably fizzy beverage. I am sure the mass market brewers could recycle the equivalent of that "bubble off" to increase gassification if they needed to.

But what do I as a mere mortal know?