A real Black Swan event is possible. And if it does it sure as hell won’t be pretty.
Once you understand them, they are not really Black Swans. People just missed the linkages.
Here’s an example from my essay “Trapping Feral Pigs and Other Parables of Modern Life.”
http://www.freerepublic.com/focus/bloggers/2949909/posts?page=35
6. The Rat Flood
This occurs in northeastern India and parts of Burma. Only in the last century was this bizarre cycle of human famine following unexplained super plagues of rats finally understood. It turns out that forests of a certain bamboo species go into a wild explosion of fruiting, producing seed nuts on a 48-year cycle, a trick of nature that had been missed until the middle of the 20th century. Intrigued by the half-century cycle of human famines reported in 1862, 1911, and 1959, modern scientists finally noticed the link between the famines and the bamboo tree cycle. By 2006, the next time the bamboo began to fruit, they were on hand to observe the complete phenomenon.
The superabundance of nuts every 48 years leads to an explosion in the population of Asian black rats, which live in the bamboo forests. Because of their rapid breeding cycle, the number of rats per acre shoots up to astronomical levels, eventually the entire mega-crop of nuts is consumed, and a lemming-like mass starvation follows.
Millions of starving rats break out from the forests in what the local people call the Rat Flood. The onrushing solid tide of scurrying rats destroys entire crops in the ground and attack unprotected granaries, leading to an immediate human famine. Millions of dying, dead and decaying rats add to the misery by polluting streams and causing other intensely nasty sanitary problems. A once-every-48-years bamboo nut super-fruiting leads to millions of rats and then to human famine.
The moral of the story: If subtle connections are missed, a radical new situation may at first wrongly be considered a Black Swan Event. But sometimes the Black Swans can be seen in advance, if seemingly unconnected links and mechanisms are properly understood in advance. And if you’re not sure what a Black Swan Event is, you definitely need to read the book.