It becomes in combination 80 fold higher over 20 years and 20 fold higher over 100 years, per unit mass.

Incidentally the reaction from Methane to CO2 produces 2.5 times more mass of CO2 than the Methane it starts with, which is one reason why the impact remains quite high. And of course everyone knows Methane emissions are relatively low, otherwise given their potency their effect on GHG warming would be a lot more than the 15% of thereabouts which it is at the moment.

This is all like attacking an IPCC claim that the sea level is going to rise by 1m over 100 years by saying it won’t rise by 5m, but by on average 1cm a year for 100 years. We know that already.