«Even our upper estimate, 0.01 bar, is an insignificant amount in comparison to the atmosphere required to maintain a sufficiently strong greenhouse effect, about 1 bar or more according to climate models.» (sciencedaily.com)
At higher elevations, where the air is colder, this increase in moisture has a much stronger greenhouse effect, following a logarithmic relationship. (psmag.com)
Indeed, physical theory would lead us to expect just that, with a relatively stronger greenhouse effect decreasing latitudinal temperature gradients. (realclimate.org)