A substantial reduction in water vapor (shown below, from Lacis et al (2010) as well as increase in the surface albedo are important feedbacks here, showing that removing the non-condensing greenhouse gases (mostly CO2) in the atmosphere can collapse nearly the entire terrestrial greenhouse effect. (skepticalscience.com)
Non-condensing greenhouse gases, which account for 25 % of the total terrestrial greenhouse effect, thus serve to provide the stable temperature structure that sustains the current levels of atmospheric water vapor and clouds via feedback processes that account for the remaining 75 % of the greenhouse effect. (pubs.giss.nasa.gov)
Scientifically, the meteorologists, climatologists, and atmospheric physicists, who were responsible for «discovering» the human contribution to the terrestrial greenhouse effect, have been the most consistent champions of its importance, while the solar physics community, and especially those interested in solar - terrestrial relations, have increasingly stressed the possible importance of the long - term variations of the solar constant as the chief cause of climate change. (stsci.edu)