Chapter 4Resource and Environment

In 1968 an American biologist, Paul Ehrlich, published a popular book entitled Population Bomb (Ehrlich, 1968), in which he predicted that the earth would not be able to sustain an explosive growth in population. In 1972, in a report entitled “The Limit for Growth” (available online at, several environmentalists predicted population growth would cause famine, pollution, and the depletion of natural resources. The report forecast that the world would run out of gold in 1981, oil in 1992, and copper in 1993. Of course, these predictions turned out to be very wrong, but many people still worry that overpopulation will eventually lead to resource depletion and damage the prospects of long-term economic growth.

I am often asked the question: What is the earth's carrying capacity? According to a meta-analysis of 69 past studies that have assessed the limit of world population (Van Den Burgh and Rietveld, 2004), the estimates range from 7 billion to 1,000 billion. Interestingly, the estimates kept rising with the growth in world population. Before 1950, the medium estimate was 6.1 billion; after 1950, the medium estimate was 160 billion. Malthus once predicted that the limit of the world's population was 1 billion. Earth is now home to 7 billion people. Owing to the great demographic shift currently occurring, the world's population will likely stop growing at around 10 billion. Almost all economists think that the earth can comfortably ...

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