Some low life political activists with extremist views (Peter Singer, Geoff Russell, Barry Brook) object to a tiny part of the article discussed here in Climate Fever.

Nicolette Hahn Niman (“The Carnivore’s Dilemma,” Op-Ed, Oct. 31) is simply wrong in suggesting that grass-fed beef produces less methane than feed-lot meat. It is the other way around, with grass-fed animals producing up to three times more methane.

Why is that? It's because grass fed ruminants eat cellulose, and digest it to get energy that is not available to other animals. People can't do it, no other type of animal can do it. Any cellulose that they happen to eat passes through them undigested, it's just fiber. But bacteria will digest it eventually, and emit methane.

Feed lots use starchy foods such as corn to get animals very fat, very quickly. Such foods are low in cellulose, but the plants that they came from have plenty, and it will be consumed by bacteria and emit methane.

It's only an accounting trick. The issue isn't what animals do or don't eat, it's what is grown since in the end the bacteria will have their way. There is a benefit to passing that cellulose through a ruminant since they live on the energy that would otherwise go to waste. In a sense the ruminant is free: it has no effect on the carbon cycle. To stop methane emission one must stop growing plants.

In any case, globally, only 8 percent of all meat is produced in natural grazing systems, and there is little available unforested land suitable for such systems. To replace factory-farmed meat without further tropical forest destruction is impossible.

This is what is technically known as a slimebag argument: it's purpose is to conceal information and pass off twisted logic as sound. One can't argue that vast quantities of crops are grown to feed animals and also claim that there is no place to practice natural grazing except forests. Obviously, the land used to grow crops for animals can be used to graze animals.

Robin makes some interesting observations about slimebag arguments.

We can signal loyalty to a group by showing our confidence in its beliefs. And our ability to offer many reasonable arguments for its beliefs suggests such confidence. But sometimes we can show even stronger loyalty by showing a willingness to embrace unreasonable arguments for our group’s beliefs. Someone who supports a group because he thinks it has reasonable supporting arguments might well desert that group should he find better arguments against it. Someone willing to embrace unreasonable arguments for his group shows a willingness to continue supporting them no matter which way the argument winds blow.

Singer and fellow travelers specialize in unreasonable arguments, ones that are immune to reason since they all know that they are nonsensical. That's the point. They will not be swayed by facts or reason, they have unreasoning beliefs. You can count on them. They will never admit error or change beliefs since facts and reason make no contribution to their views.