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Demographic momentum. Demographic momentum is the tendency for growing populations to continue growing after a fertility decline because of their young age distribution. This is important because once this happens a country moves to a different stage in the demographic transition model .
Population momentum is a consequence of the demographic transition.Population momentum explains why a population will continue to grow even if the fertility rate declines. . Population momentum occurs because it is not only the number of children per woman that determine population growth, but also the number of women in reproductive
Human overpopulation. Human overpopulation (or human population overshoot) describes a concern that human populations may become too large to be sustained by their environment or resources in the long term. The topic is usually discussed in the context of world population, though it may concern individual nations, regions, and cities.
Demographic transition. In demography, demographic transition is a phenomenon and theory which refers to the historical shift from high birth rates and high death rates in societies with minimal technology, education (especially of women) and economic development, to low birth rates and low death rates in societies with advanced technology ...
The Demography of the World Population from 1950 to 2100. Data source: United Nations — World Population Prospects 2017. Demography (from Ancient Greek δῆμος (dêmos) 'people, society', and -γραφία (-graphía) 'writing, drawing, description') is the statistical study of human populations: their size, composition (e.g., ethnic group, age), and how they change through the interplay ...
The TFR (sometimes called TPFR—total period fertility rate) is a better index of fertility than the crude birth rate (annual number of births per thousand population) because it is independent of the age structure of the population, but it is a poorer estimate of actual completed family size than the total cohort fertility rate, which is ...
Migration can have a significant effect on population change. Global south–south migration accounts for 38% of total migration, and global south–north for 34%. For example, the United Nations reports that during the period 2010–2020, fourteen countries will have seen a net inflow of more than one million migrants, while ten countries will have seen a net outflow of similar proportions.
Demographic history is the reconstructed record of human population in the past. Given the lack of population records prior to the 1950s, there are many gaps in our record of demographic history. Historical demographers must make do with estimates, models and extrapolations. For the demographic methodology, see historical demography .