The numbers game

Posted: 4 February 2008

The rapid growth of the world population is a relatively recent phenomenon in the history of the world. The population of the world 2,000 years ago was about 300 million. For a very long time, because of high death rates, population did not grow significantly, with periods of growth followed by periods of decline. It took more than 1,600 years for the world population to double to 600 million.

Today, although the rate of global population increase peaked over 30 years ago, world population is still growing by over 200,000 people every day, or 75 million a year - the equivalent of a San Francisco every week and almost a Germany every year. The momentum of this growth derives from the huge numbers of people entering the reproductive age group who are now having children (though fewer than their parents).

Population increase picked up in Europe in the 19th century following health and hygiene improvements in the wake of the industrial revolution. But the very rapid growth of world population only started in 1950, with a sharp reduction in mortality in the less developed regions. By the year 2000, the population was some 6,055 million, nearly two-and-a-half times the population in 1950. It is expected to reach 7 billion by 2015.

Changing forecasts

According to the lastest projections, issued by the UN Population Division in 2006, world population will rise by 2.5 billion people from today’s 6.7 billion to 9.2 billion in 2050. This is a slight increase on the figures projected in 2004 of 9.1 billion.

This is despite the fact that the UN now assumes that family size will probably fall below the replacement level of 2.1 children in most developing countries at some time in this century. Indeed by 2050 it projects that three out of four less developed countries will be in that category. It is also despite taking into account the impact of HIV/AIDS.

Looking further ahead, the UN Population Division attempted in 2004 to provide possible population scenarios for the next 300 years. It concluded that,under the medium variant, world population will peak at around 9.3 billion in 2075 and stabilize in 2300 at around 9 billion. However, the uncertainty of such long range projections means that the figure in 2300 could be as high as 36.4 billion or as low as 2.3 billion.

World population milestones

According to US Census Bureau projections world population reached:

1 billion in 18042 billion in 1927 (123 years later)3 billion in 1960 (33 years later)4 billion in 1974 (14 years later)5 billion in 1987 (13 years later)6 billion in 1999 (12 years later)

And world population is likely to reach:7 billion in 2012 (13 years later)8 billion in 2026 (14 years later)9 billion in 2042 (16 years later)

Link to US Census Bureau World Population Clock

Rates of increase

With the declines in fertility in most of the world, the global growth rate of population has been decreasing since its peak of 2.0 per cent in 1965-1970. Today, the world's population is growing at 1.1 per cent per year, with an annual net addition of 75 million people. The annual population increment is expected to further decline gradually to some 72 million in 2015-2020, and then sharply to around 29 million in 2045-2050. By then, the annual population growth rate should be quite low at around 0.4 per cent.

The population of the world's 49 poorest countries is rising rapidly, by 2.4 per cent per year. That's nearly 10 times the 0.25 peer cent annual growth rate in industrial nations.

Indeed, 97 per cent of the world population increase takes place in the less developed regions. In recent years the population of Asia has increased by 50 million each year, the population of Africa by 17 million, and that of Latin America and the Caribbean by nearly 8 million. Sub-Saharan Africa has the highest growth rate among all major areas (1.9 per cent), with some countries growing at over 3 per cent. Europe, one the other hand, has a zero growth rate, with a negative rate of -0.5 per cent in Eastern Europe.

Between 2000 and 2050, eight countries - India, Pakistan, Nigeria, USA, China, Bangladesh, Ethiopia and the Dem. Rep. of Congo, are expected to account for half of the world's projected population growth. (See box below for current top contributors.)

The United Nations Population Division (UNPD) projects that the population of the Democratic Republic of Congo will grow more than three times from 53 million in 2003 to 177 million in 2050. For this same time period, Pakistan and Ethiopia are each projected to grow more than twice their current sizes - from 154 to 349 million and 71 to 170 million, respectively. The population of India will grow by nearly half a billion to 1.5 billion people by 2050 and the US will also add another 115 million to its count - nearly 40% of its population of 294 million in 2003.

Changing patterns

Different demographic growth rates are changing the distribution of the world's people. While in 1950, Europe and Northern America accounted for 28.5 per cent of the world population, that share fell to 17.2 per cent in 2000, and it is expected to further decline to 12.1 per cent in 2050.

Conversely, Africa's share of world population share rose from 8.8 per cent in 1950 to 13.1 per cent in 2000 and is projected to reach 20.2 per cent in 2050, although the impact of AIDS may not be fully factored into this projection.

Nigeria's population has grown from 89 million to an estimated 140 million people since the last count in 1991, according to census figures released in January 2007. It is growing at 3.2 per cent, a rate which, if unchanged, would double population again in 22 years. Egypt, with 77 million people, is Africa's second-most populous nation.

The shares of Asia and Latin America in 2050 are relatively more stable at approximately 58.5 per cent and 8.6 per cent, respectively.

According to Gu Baochang, deputy secretary-general of the China Family Planning Association, China’s birth rate was 15 per thousand in 2003 and its natural population growth rate was 9 per thousand, lower than the global average of 22 per thousand and 13 per thousand respectively. However, in the same year, China, the most populous country in the world, had an increase in population of 11 million – even higher than the 10.3 million growth of 1950. China's population of 1.3 billion is expected to reach 1.6 billion around 2050.

Link to World Population Propsects: the 2006 Revision (UN Population Division)