[Xylakant]

Water is the only gas of the three that condenses in atmospheric conditions. The total amount of water vapor that air (or the atmosphere) can hold depends on temperature more than anything else, excess water remains in the atmosphere for days only. This seems like good overview.

https://www.newscientist.com/article/dn11652-climate-myths-c...

[labster]

But ultimately on Earth, even in the dry polar latitudes, there’s certainly enough water to absorb everything in the H2O spectrum lines. The atmosphere is lousy with water, generally 1-3%, meaning it is usually the third most abundant gas.

[Xylakant]

Sure, but the question here is “does the water vapor from burning Methane add to the vapor in the atmosphere?”, which is different from “is water vapor the most important contributor to the greenhouse effect?”