Over at FuturePundit, Randall Parker spent some time a couple of weeks ago to go over all the large-scale disasters that shook the 19th century (everything from gigantic volcanic eruptions to solar storms). His question: what happens when one of these hits our more complex and interconnected civilization?
In a different, but conceptually related analysis, Charles Stross asks How Habitable is the Earth, and answers "only in extremely limited places and times": humans evolved under an extremely specific set of circumstances--circumstances that could easily change. (Amusingly, Stross fools around and uses decerebrate meat puppets as his planetary explorers, and discovers that many of his blog readers take even his jokes with grim seriousness: clearly a cult in the making, though Stross seems unwilling to lead it).
Years ago, in his novel A Gift From Earth, Larry Niven postulated a planetary probe poorly programmed to seek "habitable areas". On Mt. Lookatthat, a plateau rises out of an otherwise Venus-like atmosphere, and so humans are sent to settle what is really an island.
The farmers and city dwellers of the dry Southwest take the maximum rainfall ever recorded as the standard, and base their plans on it, though "plans" is an exaggerated word for what they do.
There are always Black Swans, big out-of-norm events. But there are, more importantly, a larger number of gray swans of various darkness, mostly uncorrelated with each other. Our technological civilization seems to have grown rapidly in a period unusually empty of such events, and treats this unusually wide zone of habitability as normal. And, aside from a catastrophic black swan (e.g., a major asteroid strike), it can now probably deal with any such event.
But what happens when there are a few gray swans in close succession? Regular readers know I've been reading about the fall of the Roman Empire (as in this discussion of Ward-Perkins, and this one on Heather). It's hard to really get clear, because a large number of negative events (plague, tribal reorganization, internal political chaos) came together, not one gigantic one.
We could get a large volcanic eruption and a major solar storm that knocks out communication, during a time of political instability and financial disruption. Our civilization is not a fragile flower, but it certainly has its breaking point. With one big disaster you have something to fight and unite against (and write disaster novels about). Is a group (flock? herd? --swans don't seem to have been hunted enough for a nifty collective noun to be agreed to) of gray swans a conceptuallly different situation than a black swan?
If we stay in the game long enough, we'll have a chance to find out.