Translating alternative assumptions about the factors affecting population change – fertility, mortality and migration – into projections of future population size.
Scientists working in ecology, climatology, hydrology, agriculture, energy and other fields increasingly demand long-term population figures that explicitly address the issue of uncertainty. Their scenario analyses are becoming more sophisticated; often they are more interested in the boundaries of future world population rather than a best guess. Moreover consideration of alternative population scenarios is essential in the design of robust policy options.
Population growth is one of the most controversial issues of our time; almost everyone agrees that it affects environmental, economic and political stability, both globally and regionally, but there is little consensus on what, if anything, should be done about it.
We know the approximate number of future parents. What we do not know is the number of children that they are going to have.