I don't think you need fart bags, cows fed seaweed emit significantly less methane -https://e360.yale.edu/features/how-eating-seaweed-can-help-c....

Cattle is one main reason, second one is clearing forest for industrial agriculture like soybean and palm oil plantations. Third one is logging for wood products.

Essentially they are all because of overpopulation and massively increased demand for these products.