> There is limited OH in the atmosphere. As a result, more methane “uses up” the OH.
> So, why not produce a bunch of OH? Because OH has a half life of less than a second. Hmm.
These two statements seem to contradict? If the chemokinetics of OH generation is less than a second, then how can it be used up in the atmosphere?
Assuming the <1 second kinetic is correct, there must be a dynamic equilibrium producing it in the atmosphere to begin with. In such a case OH is not truly being used up in any real sense. It's whatever that generates OH is being used up, and that can be artificially boosted.
It's because that statement is incredibly wrong. Methane concentrations in atmosphere are 8 orders of magnitude higher than OH. More methane in the atmosphere has exactly 0 effect on OH. And you can't inject OH into atmosphere either because it will react with pretty much anything it comes in contact with.
In this case, annual reaction mass of OH is more important than the concentration at any given time. The concentration of any highly reactive molecule will be very low, but that doesn't tell you how much was created or consumed.
Methane levels don't impact OH levels (it is always consumed immediately). OH generation levels can impact methane levels. CO levels can compete with methane for OH as is it generated.
Look at it this way: there's a finite amount of OH radicals being produced each interval of time, which reacts with some CH4 and disappears in the reaction.
You are correct that OH radicals regenerate, but more methane => "breakdown capacity" becomes overwhelmed.
This is known as zeroth order kinetics, similar to alcohol metabolism. Drinking 2 beers = 3 hours until sobriety; 4 beers = 6 hours. Your liver has a fixed capacity, so drinking twice as much doesn't double the metabolic rate.
I'll add that you're also entirely correct: if there's some long lived chemical that catalyzes OH formation, sending that up instead might be a good remedy IMO. If there's no collateral toxicity...
> So, why not produce a bunch of OH? Because OH has a half life of less than a second. Hmm.
These two statements seem to contradict? If the chemokinetics of OH generation is less than a second, then how can it be used up in the atmosphere?
Assuming the <1 second kinetic is correct, there must be a dynamic equilibrium producing it in the atmosphere to begin with. In such a case OH is not truly being used up in any real sense. It's whatever that generates OH is being used up, and that can be artificially boosted.