1) No one really understands clouds, which can either reflect light back into space (cooling), or reflect it back down to earth (heating) depending on various factors.
I.e. increased heat -> increased moisture ->
net effect on clouds2) The body of evidence that warming is occurring is actually showing pretty small scale changes so far (far, far less than what occurs during the yearly cycle). Whether the theorized positive feedback loop occurs depends on what the clouds do... which no one really understands.
All the models ASSUME clouds will work as a positive feedback factor. There is some basis for this but also preliminary satellite evidence that the opposite is true. Even a decade of perfect climate data isn't enough to tell either way since there are so many long and medium scale cycles overlapping each other.
At the very least, the idea that there is "incontrovertible proof" CO2 is the cause is overblown and likely a political move. The correlation is there for sure, causation not so much.
