This class of thing is known as a Global Catastrophic Risk, for a more general overview, one can have a look at the Wikipedia article: http://www.wikiwand.com/e

This class of thing is known as a Global Catastrophic Risk, for a more general overview, one can have a look at the Wikipedia article: http://www.wikiwand.com/en/Global_catastrophic_risk http://www.wikiwand.com/en/Global_catastrophic_risk