Originally Posted by W*GS
H2O as vapor isn't a forcing, it's a feedback. It condenses out too easily and is present almost entirely in the lower atmosphere and isn't well-mixed.
CO2 doesn't condense out, has a lifetime of decades to centuries, and is well-mixed throughout the column.
Are you familiar with Richard Alley's 2009 AGU Bjerknes lecture, "The Biggest Control Knob: Carbon Dioxide in Earth's Climate History"?
What makes your claim more credible than his science?
The stability of the vapor makes zero difference. Only it's average contribution to the makeup of the atmosphere. If I could invent a machine that sequestered atmospheric CO2 but then spit an equal amount of CO2 out the other side, you'd say this did nothing to prevent greenhouse warming. Water vapor becoming water and then vapor again is essentially the same thing.