World population in transition:An integrated regional modelling framework

The world’s population reached the milestone of 6 billion in 1999 and increases by around 150 persons each minute. In the last few decades, population growth seen in the light of limited natural and economic resources has become of growing concern. Now, at the beginning of a new millennium, questions are arising on what is in store for the world of the 21st century. Population growth is the outcome of three basic demographic processes: fertility, mortality and migration. The demographic transition is referred to as the sequential decline of death rates, and, with a delay, birth rates induced by improvements in socio-economic and environmental conditions. In the developed countries, the demographic transition has already been completed. These countries are now characterised by fertility levels even far below replacement level and a life expectancy above 75 years of age. Although the population in developed countries hardly increases, the process of ageing is still going on and may have a further impact on society and the economy. It took developed countries 50 to 100 years to complete the demographic transition, while the developing countries will only need 30 years. As a consequence of such a rapid demographic transition, major societal changes may be encountered in the developing countries, which we will have to cope with in the 21st century. The project resulting in this book, World population in transition, provides an integrated modelling framework allowing us to describe, position and analyse various population issues. A systems dynamic modelling approach is applied to describe the demographic transition as a composite of its underlying components: the epidemiological and fertility transition. Future fertility behaviour and mortality patterns in major world regions are explored under varying socio-economic and environmental conditions by making use of the computer simulation model, PHOENIX. This project was carried out as a collaborative effort of the National Institute of Public Health and the Environment (RIVM) and the Population Research Centre of the University of Groningen