One of the economists like to follow is George Mason University professor, Tyler Cowen. Attached is his presentation about black swans.
Let’s start by defining the term.
black swan – “An event or occurrence that deviates beyond what is normally expected of a situation and that would be extremely difficult to predict. This term was popularized by Nassim Nicholas Taleb, a finance professor and former Wall Street trader”. http://www.investopedia.com/terms/b/blackswan.asp#ixzz25JnbMj4c