Economists do not have a great reputation for forecasting accuracy. Arguably, among the worst records is that of Thomas Malthus, the pessimistic Englishman who two centuries ago wrote, “The power of population is so superior to the power in the earth to produce subsistence for man that premature death must in some shape or other visit the human race."
Thus far that prediction has turned out to be incorrect. Between 1820 and the year 2000, the world’s population expanded six-fold and economic output multiplied by more than 50. But as pointed out by writer Eduardo Porter, Malthus’s prediction was based on an eminently sensible premise – the Earth’s carrying capacity is limited. Recently, the United Nations Intergovernmental Panel on Climate Change warned that we may rapidly be approaching that limit.
The list of present damages outlined by the panel includes melting ice caps, rising sea levels, stressed water supplies and heat waves. The report is also more pessimistic than earlier reports about prospects for additional grain production in the globe’s more temperate zones. That’s potentially problematic -- studies indicate that feeding more than 9 billion people in 2050 will require 70 percent more calories than the world consumes today.