• Archived Video

•Clive A. Edwards Biography

•Lecture Abstract

•Lecture Homepage

University Distinguished Lecture

The Future of Human Populations: Energy, Food and Water Availability in the 21st Century

By
Clive A. Edwards

Abstract

In 1798, Thomas Malthus, a British clergyman and intellectual warned that, while there was a tendency for human populations to grow exponentially, he believed that food supplies could grow only linearly and would eventually become limiting. However, regional food shortages, diseases, war, and water shortages have tended to limit population increases, and the efficiency of food production in developed countries has improved greatly particularly over the last 50 years. Nevertheless, during the last half-century the global population has more than doubled from 2.5 billion in 1950 to 6 billion in October 2000. Forecasts of future global human populations have ranged from 7.7 billion to 13 billion by 2050.

Enormous increases of energy, food and water supplies are absolutely essential to support such expanded populations. Fossil fuels such as oil, coal and natural gas are finite resources, and the availability of oil and oil-based chemicals such as pesticides and fertilizers, will peak by 2010 and will be exhausted, or prohibitively expensive, by 2050. Known sources of renewable energy such as nuclear, solar, wind, and water power systems have the potential to supply only 20-30% of our current energy needs. Since 1980 the per capita production of food has been decreasing progressively due to: loss of land; soil erosion and exhaustion; deforestation; and urbanization. Fresh water supplies are decreasing globally and agriculture consumes more than 93% of the available water for irrigation. Additionally, gaseous emissions have been predicted to raise global temperatures by as much as 10¡C in the next 100 years, with the potential for drastic effects on agricultural production.

Even if innovative renewable energy technologies are developed; the losses of productive soils retarded; biological alternatives to energy-based chemicals discovered; new sources of fresh water found; and climatic changes slowed; the world population cannot continue to increase at its current rates. We may already be close to peak human populations, which may have to stabilize in the long term at 2-3 billion, unless there are enormous technological developments in food production and environmental conservation.