https://en.wikipedia.org/wiki/Methane_emissions

fossil fuels contribute 33% farm animals contribute 30%

Not astronomically; marginally. Anyone who's been around herbivore farm animals will tell you they fart. A lot.

Then again, farm plants are a further 18%.

Those fossil fuels emit what otherwise wouldn't be available in the carbon cycle.

A cow that's fed on gras and farts emits nothing that that gras didn't pick up and contributes virtually nothing to climate change in the long term.

> Then again, farm plants are a further 18%.

Yeah, but they also provide 80% of the world's calories to animals' 20%

With corn based feeding.

> farm plants are a further 18%

Apparently mainly rice growing. I knew paddy fields were bad, but I didn't know they were that bad. Per calorie I am sure it is more like a tenth that of ruminants, perhaps less, but still worth replacing with other carbohydrates.