Aidan, typical green gooble gook to try to distract from the facts.

It matters not at all, the length of residency that any particular molecule of water vapour in the atmosphere. The fact is that a percentage is displaced by CO2 permanently. Any increase in CO2 means a reduction in atmospheric water vapour.

Hasbeen,
Far from trying to distract from the facts, I'm trying to explain the facts. I'm sorry if you regard it as gobbledegook; try rereading it and if there's anything you still don't understand then tell me and I will try to explain it more clearly.

> The fact is that a percentage is displaced by CO2 permanently.
No, the EXTRAORDINARY CLAIM is that a percentage of water vapour is displaced by CO2 permanently. You have not posted any evidence of such a link, and nor is there any credible mechanism for such a relationship. I speculated that you were misinterpreting the results of a study on the effect of CO2 on transpiration - which was a very significant finding, but nowhere near sufficient to invert the overall relationship between water vapour and CO2 in the way you suggest.