How is it possible that almost 100% of the world's policy makers have uncritically accepted the veracity of computer modeling exercises (used by IPCC climatologists) as "absolute proof" that carbon dioxide is the main cause of global warming?

Very easily it is either a smokescreen or they are creating a common enemy "to unite humanity to deal with a problem".
As a consequence more control of people
Which means monetary, political, social, even religious control.
(the danger of a unified world).
That's my opinion you can treat it as a conspiracy or as you like.