Out of the Box Thinking, Well-Structured,
I recommend this book, updated from the 1997 version, very highly. It is a well-structured look at all sorts of “jokers” or “wild cards”, and I particularly like the methodology for calculating impact across nine factors (rate of change, reach, vulnerability, outcome, timing, opposition, power factor, foresight factor, and quality), all combining to create the tenth “impact index”. After a short introduction, each major “earth-shaking” wild card is covered with two pages of clear graphics that are easy to absorb.
See the 2007 book, Seeing the Invisible: National Security Intelligence in an Uncertain Age