Historically, war has been something where a truly large number of people and a large fraction of world economy could be "united". It's hard to imagine a disast

Historically, war has been something where a truly large number of people and a large fraction of world economy could be "united". It's hard to imagine a disaster that would require the same level of both world GDP focus AND individual human labor participation in the modern economy. COVID seems the best example, but the GDP impact seems to have been largely negative in the sense of needing more factories to (temporarily) close more than new production to come on line. I'm quite curious to hear brainstorms of acute disaster scenarios that would drive a big transition of production to something special...