The simplicity is this namely....
1. Grass absorbs carbon (CO2) from the atmosphere.
2. Cows eat grass and belch, returning carbon to the atmosphere as methane (CH4).
3. As a greenhouse gas, methane is massively worse than CO2.
4. Methane survives a very short time, on a global warming timescale.
5. Methane rapidly breaks down and reverts back to the CO2 we started with.
Effect of a million cows on global warming?
Effect on global warming of reducing the herd by a million cows?
More if you need it.
Thanks to Ron Allan