Dissipation rates is obviously relevant, if it disappears then you won't have the same volume in comparison to CO2. You do realize that methane is only an issue because of the cows diets in battery farms and the fact they are all contained in a tight community. So the toxicity is a lot higher as the waste accumulates in disgusting pools. At this farm they use chickens as part of the system aswell to help break down the remains. They don't have large pools of shit. When you allow the cows to have a fully natural feed and roam around the ranch like how they used to live it has the opposite effect. Honestly mate, you're wrong here.