I would add that presumably water vapour, methane and carbon dioxide have been in the atmosphere influencing temperatures since before anthropogenic climate change. I imagine rising concentrations of atmospheric water vapour are partly a consequence of emissions of carbon dioxide and methane emissions. (I believe that methane breaks down into chemicals including water.)
I imagine that humans are more responsible for levels of atmospheric water vapour indirectly (through carbon dioxide and methane emissions) than directly.
I imagine temperature and concentrations of atmospheric water vapour are in equilibrium in the absence of changes in the concentrations of other greenhouse gases.
Maybe I should have written my comment as questions. I would have phrased it differently if I had sources.
My main reason for answering the parent comment was to suggest that most of any increase in water in the atmosphere might largely result from warming due to other greenhouse gases. It might be the case that global warming is almost solely a function of greenhouse gases other than water vapour, even if it largely had its effect via water vapour.
I would add that presumably water vapour, methane and carbon dioxide have been in the atmosphere influencing temperatures since before anthropogenic climate change. I imagine rising concentrations of atmospheric water vapour are partly a consequence of emissions of carbon dioxide and methane emissions. (I believe that methane breaks down into chemicals including water.)
I imagine that humans are more responsible for levels of atmospheric water vapour indirectly (through carbon dioxide and methane emissions) than directly.
I imagine temperature and concentrations of atmospheric water vapour are in equilibrium in the absence of changes in the concentrations of other greenhouse gases.