Almost all of the "greenhouse affect" is due to water vapor, which can be near 5% in extreme cases. That would be 50,000 parts per million.

CO₂ is about 365 PPM.

Methane is 1.7 PPM.

Methane nas no measurable affect on the ambient air temperature at 4" above the ground or ocean.

The influence of CO₂ is a matter of some debate. It certainly is not something that accutate climate projections can be based on.