Demographic transition model
Germany as the stage 5 country
Stage 1 to stage 3 countries
Population momentum refers to population growth or decline, which continues despite the falling or rising birth or fertility rate. Population momentum is the propensity for a growing population to continue growing even through fertility or birth rate is declining (positive momentum). On the other hand, it also includes the tendency for a population to continue to fall despite a rise in birth rate (negative momentum).
Population momentum naturally occurs towards the end of stage 3 of demographic transition. Even though the birth rate may be falling in a country, the natural increase in terms of total number may be rising due to population momentum. Positive momentum is typical for a stage 3 to 4 country in demographic transition with high base of youthful population. Negative momentum has been observed in case of the stage 5 countries with high numbers of elderly population.
- Despite the decline in overall population growth rate, the absolute size of the human population will continue to increase over the next several decades because of population momentum. At present nearly one third of the world’s population is under 15 years of age and therefore has not yet reached childbearing age. Because this demographic group is so large in absolute numbers, even if each woman has fewer children than in the past, there will still be a significant increase in global population over the next several decades. This is an example of positive population momentum.
- Most of the population growth over the next several decades is expected to occur in developing countries, where growth rates are generally higher than for developed countries. The United States is an exception, with one of the most rapidly growing populations of any developed nation.