The essence of the proposition that Professor William Rees presents in The Human Ecology of Overshoot: Why a Major ‘Population Correction’ Is Inevitable, is that human population, consumption and pollution have combined to exceed the ability of our planet’s limited ecological systems to sustain it. This situation is not unusual. It has commonly happened in the past with other civilizations, and is a frequent and natural occurrence in all biological systems. Overshoot, then, is just the inability of species to be supported by their environment if they exceed its carrying capacity. This, Professor Rees suggests, is now the condition in which humanity finds itself. Earth is not big enough, rich enough, or regenerative enough to deal with the impact of more than 8 billion people who are hungry, materialistic, wasteful and unrestrained. The result, he suggests, will be a major “population correction” by the end of this century.