First, there is no such thing as global warming. Its propaganda produced by people who use fear to control the rest of the population.
Second, belief is a tricky substance, it seems to take a fairly large amount of it before it reaches "critical mass". But once it does, look out.
More to the point, than bigfoot, why did we create UFO's?
I mean after all, bigfoot is fairly harmless.
He hides in the woods after all.
But UFO's can abduct anyone, anytime at will. Now THATS scary.