[himinlomax]

That carbon in cow farts & burps was grass yesterday, which was atmospheric CO2 last week. Cows are not fed petroleum products, though some petroleum may be used in the production of industrial feed (but not or much less for pasture feeding).

Atmospheric CH4 does not "do harm" as such, it's indeed a greenhouse gas that contributes to global warming in proportion to its prevalence. Said prevalence, as I'm trying to point out, is proportional to the number of heads of cattle. As such, if we don't increase the number of heads significantly, the impact will be constant.

Contrast with fossil fuels for, say, transportation: their impact on greenhouse effect is constantly increasing at a rate proportional to the number of cars/planes/trips.

Or put another way: we have to stop using ICE cars and planes altogether to stop increasing greenhouse effect; we only have to keep eating the same amount of beef and cheese to stop their impact.