I'm not sure how you get a total global outage in a distributed system. Lets say a major transit provider (Century link for example) advertises traffic as a "go via me", but then drops the traffic, lets also assume it drops the costs of routes to pretty much zero. That would certainly have a major effect, until their customers/peers stop their peers.

That might be tricky if they are remote and not on the same AS as their router access points and have no completely out of band access, but you're still talking hours at most.