Like TFA says : it doesn't end up in the same place in the atmosphere ? (A little bit like Ozone is bad to have around us, but extremely important in ~high (?) atmosphere?)
IIRC (but I am way less certain of this) there's also extra issue with methane degrading into not only CO2, but also water, and in a place where they increase the greenhouse effect rather than reducing it ?
P.S.: Also water vapor is an extremely powerful greenhouse gas... but I have no idea which fraction of water ends up in this phase under these conditions, nor how long water lasts there...
P.P.S.: Oh, also, I just remembered : CH4 (+X O2) => CO2 + H2O, is just one of many reactions that happen... IIRC this is also where the ozone layer is and all of these ingredients and products all have an effect. But in the end it's all oversimplified into CO2 has this greenhouse effect, and CH4 that one - by the climatologists ?
(All of this from climatology 101 that I had to take a decade ago, because there was no other option for a remote physics degree...)
