Paul Ehrlich's Population Bomb book of 1968 got me thinking then about how to refute his thesis that civilization would collapse in a few decades. What Ehrlich overlooked was the green revolution in agriculture that can feed many more people than one could imagine in the 1960's. The Bomb bombed. However, Ehrlich has another doomsday forecast based on the effects of these four horsemen: toxics in the environment, climate change, overconsumption, and again too many people on th