Population doubling time
Also called: Doubling time · Topic: World Population: Distribution, Density, Growth and Migration · NCERT: Class 12, Ch 1 "Population: Distribution, Density, Growth and Composition"
Meaning
Population doubling time is the number of years a population takes to double if it keeps growing at its present yearly rate. A quick rule gives it: doubling time ≈ 70 ÷ annual growth rate (in per cent). The faster the growth, the shorter the doubling time. It shows in a simple way how fast pressure on land, food and jobs will rise.
Example
India grew at about 1.64 per cent a year in 2001-11. Dividing 70 by 1.64 gives about 43 years to double. The world grows at about 0.9 per cent a year, which gives about 75-80 years (verify current).
Don't confuse with
- Growth rate: this is the percentage change in a population over a period. Doubling time turns that rate into the number of years the population takes to double.
Related concepts
- Natural growth of population
- Actual growth of population
- Positive growth of population
- Negative growth of population