I am currently in the midst of reading the Black Swan by Nassim Nicholas Taleb. The author describes a Black Swan as a high-impact, hard-to-predict, rare event beyond the realm of normal expectations.

In the book, Taleb states he is often asked by members of the media to predict the next 10 Black Swans. While the question itself proves they missed the point of the book entirely, I do believe that at least one Black Swan is foreseeable.