I'd say that Climate change certainly has the potential to present significant mortal danger, although it probably won't be Doomsday. But regardless, the point is that there are far more problems of various scales that have absolutely nothing to do with Islam, let alone Militant Islam, than there are problems that do.
Incidentally, some estimates say that in the seven years from 2006, around 120,000 people in Mexico died. That's quite a lot (although the official figure is something closer to half that). Just because it's confined to Mexico doesn't stop it being a serious problem that can just be overlooked.
Oh, and while I'm thinking about it, Tuberculosis still is wholly or partly responsible for over a million deaths a year. That certainly IS a mortal danger that vastly overshadows anything Al Qaeda et al can manage. Let's hope they don't try too hard to outcompete TB, though.
"Most of the world's problems"? However serious Militant Islam undoubtedly is, that's just hyperbole.