At the beginning of the 21st century Botswana, Mozambique, and Namibia are coping simultaneously with three enormous forces: (1) high rates of HIV/AIDS, (2) the large-scale restructuring of their economies, and (3) global climate change. Any one of these would be difficult to handle. The three taken together produce a monumental challenge for policy makers.

All of these challenges interact. For example, HIV/AIDS significantly reduces the population and therefore the demand for water just when reduced government revenues from customs duties reduce the ability of governments to finance new water infrastructure and just when global climate changes could reduce the amount of usable water, requiring further expensive water infrastructure or conservation programs.

All of these shifts are taking place in the context of rapid educational changes that affect how the countries will cope with forces that affect them. What will be the results of all these simultaneous changes? Will some of the countries face crises, while others weather the storm with ease?

Because of the interactions of the forces affecting their countries, it is becoming much more difficult to formulate appropriate policies. Policy makers need guidance in this period of rapid and profound change. It is precisely this kind of guidance that our models of population, development, and environment interactions are designed to provide.