Thirty-four times as powerful as CO2. You know what? They never say why. You know why that is? Because they heard it somewhere and they keep on repeating it. Actually, these days,34 times is at the low end of the usual claims for how powerful CH4 is compared to CO2. Earlier this year, Scientific American said it is 86 times as powerful as CO2 up from their 2010 claim that it was only 72 times as powerful.
But that aside, amuse yourself, do a search on “Why CH4 is more powerful than CO2 “