Currently, the world’s population is
6.9 7 billion and is expected to reach 10 billion by 2080 and then stabilise. The population has been growing exponentially in the past two centuries, going from just 0.75 billion in 1750 to 7 billion today. The population increase peaked in the 1960s, when the natural increase of the world’s population was 2.2%. Today, the natural increase has and is falling but it isn’t expected to level off until 2100.
The growth of the world’s population is not evenly distributed throughout the world. Depending on the economic development, the culture and many other factors, the population of different countries can vary quite significantly. Asia, for example, has experienced rapid population growth and the country of China now accounts for nearly 15% of the world’s population. Conversely, western countries such as the USA are experiencing a slow down in population growth and are expected to enter population decline fairly soon.
Population Doubling Time
Quite simply, the population doubling time is the time it takes for the population to double.
- 2% growth rate - population doubling time would be about 35 years.
- 3% growth rate - population doubling time would be about 24 years.
- 4% growth rate - population doubling time would be about 17 years.
Components of Population Change
- Life Expectancy - The average number of years a person from a specific country is expected to live.
- Birth Rate - The number of (live) people born per 1000 of the population per year (normally per km2).
- Death Rate - The number of people who die per 1000 of the population per year.
- Natural Change - The change in the size of a population caused by the interrelationship between birth and death rates. If the birth rate exceeds the death rate then the population will increase. If the death rate exceeds the birth rate then the population will decrease.
- Annual Population Change - The cumulative change to the size of a population after both natural change and migration have been accounted for.
Calculating Population Change
Population Change = Birth Rate ± Death Rate ± Migration