Population MomentumPopulation Projections.

• Why do governments need to plan for their future populations?

• Eg’s. China, Gambia, Malawi, France.

• Population momentum. The tendency for population growth to continue beyond the time that replacement-level fertility has been achieved because of a relatively high concentration of people in the childbearing years.

• For example, the absolute numbers of people in developing countries will continue to increase over the next several decades even as the rates of population growth will decline.

• This phenomenon is due to past high fertility rates which results in a large number of young people. As these youth grow older and move through reproductive ages, the greater number of births will exceed the number of deaths in the older populations

• Population Momentum• Even when total fertility declines, there is a lag period before

the rate of natural increase declines. This is because people who have already been born build momentum into the population.

• Think about what happens when you slam on the brakes of a moving vehicle. Do you stop right away?

• No, you continue to move because of momentum. The same is true of population growth. Population momentum refers to the tendency of a population to continue to grow beyond the time when replacement levels of fertility are achieved.

Replacement Rates

• Replacement rates are the number of births necessary to simply replace the current population. Momentum introduces a lag between achieving replacement levels of fertility and a leveling off of natural increase.

• A momentum factor (MF) of 1 means that natural increase is not contributing to population growth. MF > 1 means there is positive momentum in the system that will lead to population growth and MF < 1 means there is negative momentum, or the probability of population decline.

• The equation is MF = CBR x Life Expectancy at Birth

Countries with Population Momentum

Australia Spain Canada United States Norway Finland Sweden Denmark United ingdom Belgium Netherlands Luxembourg France Switzerland Austria Portugal Slovakia Serbia Bosnia and Herzegovina Republic of Macedonia Albania Greece Cyprus China South Korea Taiwan Thailand Iran Brazil

Table 1. Selected Demographic Characteristics and Population Momentum, 2007

Country

Total Populatio

n in Millions

Crude Birth Rate

Rate of

Natural

Increase

Infant Mortali

ty Rate

Total Fertility Rate

Life Expecta

ncy

Percent with HIV/AI

DS

Population

Momentum

Tunisia 10.2 17 1.1 20 2 74 0.11.25

8

Guinea-Bissau 1.7 50 3.1 117 7.1 46 3.8 2.3

Chile 16.6 15 1 8.4 2 78 0.3 1.17Vietnam 85.1 19 1.3 18 2.1 72 0.5

1.368

Liechtenstein 0.04 11 0.05 2.9 1.4 80 n/a 0.88

Kiribati 0.11 31 2.3 43 4.2 62 n/a1.92

2

Source: Population Reference Bureau World Population Data Sheet 2007