One other point on cloud feedbacks from a paleoclimate perspective — if a strong negative cloud feedback begins at modern earth temperatures, it would be unlikely for past temperatures to have exceeded modern ones. (realclimate.org)
Do orbital variations in insolation drive ice - age cycles if you have a strong negative cloud feedback? (realclimate.org)
What they find is that, even though cloud cover is reduced as the climate warms, it does not generate a strong negative cloud feedback. (realclimate.org)