Some number of the catastrophe promoters know that and pretend to be skeptical and open-minded. What they typically do is invent probabilities (complete fabricated probability distribution functions) and say "even though there might only be a [insert some value] percent chance that we are doomed, we can't take that chance".
Their argument is a trap, they want other scientists to start to argue about probabilities which quickly leads to arguments over models (which are crap but that's not a scientific rebuttal) over temperature proxies (which are crap but that's not a scientific rebuttal either), etc. In short they are attempting to get their probabilities to appear to be scientific by forcing the other side to look unscientific.
Everyone now knows to take climatologists as seriously as they take sociologists.