The absolute worst greenhouse gas on the planet is not CO2 nor is it methane.
It is (wait for it)......... water vapor.
We’re doomed!
It is (wait for it)......... water vapor.
There's certainly more water vapor than CO2, but perhaps CO2 has a bigger greenhouse effect per molecule. Do you know their relative strengths as greenhouse gases? Me either, but at least I'll try to look it up.