Andy said in a comment
It is possible to accept that there are issues with the science, in particular the Hockey Stick, and still be aware that continued emissions of greenhouse gas emissions may cause us problems.
I was thinking about writing a response. But this Crock of the Week explains the issue quite more clearly than I can. But the basic issue as far as I can see is that many CCDs appear to be religiously attached to early work done on ‘global’ temperatures that were almost entirely euro-centric. They ignore the evidence that has subsequently been gathered amongst many scientific groups using a variety of methods that substantially supports Manns early (mid-90’s) ‘Hockey-Stick’.
I get the impression that most CCDs don’t keep up to date with the emerging scientific picture. They prefer clinging to old data rather than embracing the new.
Wikipedia has a good article on the subject of the MWP in the IPCC reports. Notice the dates.