Njbunk asks:

How about a post on the effect of methane emissions on global warming? Cows probably contribute as much, maybe more, to global warming as cars. If we’re going to tax carbon emitters, we should tax methane emitters (cows) as well.

I’m not a scientist, or a cow fart expert, but my understanding is that when you see a high estimate of a cow’s contribution to global warming you’re looking at a very broad estimate of the cow’s climactic footprint. Which is to say not just his methane emissions, but the considerable amount of carbon expended in growing and transporting the grain on which he feeds. But, yes, carbon dioxide is the most important greenhouse gas because of the large quantity of emissions but it’s not actually the most pernicious on a per unit level and the case for regulating carbon emissions applies just as well to methane emissions and a few other things. There are obviously some technical issues here that I’m not conversant with, and I’m not sure it’s strictly necessary for me to become conversant with them in order to do the kind of persuasive work I’m trying to do with this blog, but you would want congress and the EPA to look at this sort of thing carefully.

The flipside of this is that one of the under-discussed social consequences of improved environmental policy would almost certainly be a large change in Americans’ beef-consumption behaviors. The difference between eating beef and eating chicken or pork in terms of climate footprint is enormous. If those climactic externalities were priced into the beef, you’d see a lot less beef eaten overall and probably a resurgence of interest in the cheaper/grosser parts of the cow.