Do the people that support AGW theory understand that there is a 50% uncertainty in the data?

This is a fact that can be checked on their own support websites at the IPCC, Royal Society, NASA GISS, etc therefore do all these people fully back any theory with 50% uncertainty as this sort of begs the question... Who are these people? Does a sceptical believer exist? What is a sceptical beliver? Or is everyone just branded a denier?