Natural Increase

The natural increase rate (NIR) is the percentage by which a population grows in a year. The term natural means that a country’s growth rate excludes migration. During the twenty-first century, the world NIR has been 1.2, meaning that the population of the world has been growing each year by 1.2%.

More than 95 percent of the natural increase is clustered in developing countries. Since 1980, 66 percent of the world’s population growth has been in Asia, 20 percent in sub-Saharan Africa, 9 percent in Latin America, 4 percent in North America, and 1 percent in Europe, including Russia.

Regional Distribution of Population Growth Since 1980

The NIR currently exceeds 2.0 percent in most countries of sub-Saharan Africa, whereas it is negative in Europe, meaning that in the absence of immigrants, population actually is declining. Regional differences in NIRs mean that most of the world’s additional people live in the countries that are least able to maintain them.

Natural Increase Rate, 2018

Pause & Reflect 2.2.1

Which region other than sub-Saharan Africa appears to have the highest natural increase rate?

Population Growth in History

The NIR was essentially zero for most of humanity’s several-hundred-thousand-year occupancy of Earth. The world NIR is lower today than its all-time peak of 2.1 percent in the 1960s, and it has declined since the 1990s. However, the NIR during the second half of the twentieth century was high by historical standards.

World Population Growth 8000 B.C.E.–2017 c.e

World Population Growth 1750–2017

Population Growth, United Kingdom

The United Kingdom’s natural increase was around 324,000 per year during the 1960s, compared with around 134,000 per year during the twenty-first century.

The number of people added each year dropped from a historic peak of 93 million in 1988 to 78 million in 1999. But in the twenty-first century, the number added annually has increased to around 85 million. The decline of this number is less sharp than the decline of the NIR because the population base is much larger now than in the past. World population increased from 3 to 4 billion in 14 years, from 4 to 5 billion in 13 years, from 5 to 6 billion in 12 years, and from 6 to 7 billion in 12 years. As the base continues to grow in the twenty-first century, a change of only one-tenth of 1 percent can produce very large swings in population growth.

World Population Growth 1950–2017

The natural increase rate affects the doubling time, which is the number of years needed to double a population, assuming a constant rate of natural increase. At the current rate of 1.2 percent per year, world population would double in about 58 years. If the same NIR continued through the twenty-first century, global population in the year 2100 would reach around 20 billion. When the NIR was 2.1 percent in 1968, doubling time was 33 years. Had the 2.1 percent rate continued into the twenty-first century, Earth’s population would currently be 10 billion instead of 8 billion. A 2.1 percent NIR through the twenty-first century would produce a total population of around 56 billion in 2100.