Indeed, methane is shorter lived than CO2 on the atmosphere. Taking that into account:
The 20-year global warming potential of methane is 84.[5][6] That is, over a 20-year period, it traps 84 times more heat per mass unit than carbon dioxide (CO2) and 32 times the effect when accounting for aerosol interactions.
The 20-year global warming potential of methane is 84.[5][6] That is, over a 20-year period, it traps 84 times more heat per mass unit than carbon dioxide (CO2) and 32 times the effect when accounting for aerosol interactions.
https://en.m.wikipedia.org/wiki/Atmospheric_methane