Even at a reduced world population of 2 billion in A.D. 2100, life for the average Earth dweller will not be as luxurious as it is for many Americans today. But the lifestyle won't be as wasteful of resources, either, the Cornell ecologist predicts. Some observers are seeing early signs that nature is taking a hand at reducing human populations through malnutrition and disease. According to the report, global climate change is beginning to contribute to the food and disease problems. Even if a worldwide limit of 2.1 children per couple were adopted tomorrow, Earth's human population would continue to increase before stabilizing at around 12 billion in more than 60 years.
Malnutrition increases the susceptibility to diseases such as diarrhea and malaria.
Grains provide 80 percent to 90 percent of the world's food. Each additional human further reduces available food per capita. The reasons for this per capita decrease in food production are a 20 percent decline in cropland per capita, a 15 percent decrease in water for irrigation and a 23 percent drop in the use of fertilizers. Considering the resources likely to be available in A.D. 2100, the optimal world population would be about 2 billion, with a standard of living about half that of the United States in the 1990s, or at the standard experienced by the average European. The study was funded by Cornell University.