Global Economy
Global population forecast at 10.1bn by year 2100; To hit 7bn this year 12 years after 6bn milestone
By Michael Hennigan, Founder and Editor of Finfacts
May 4, 2011 - 3:52 AM

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There was an estimated 1bn on the planet when Thomas Malthus penned his famous essay in 1798 - - up from 310m in 1000 AD and 300m in 0 AD. In the period to 1924, when the population grew to 2bn, there was a remarkable advance in technology and fall in the death rate through improved hygiene. American historian David Christian says that in the last two centuries, humans have learned to tap the huge stores of energy buried millions of years ago in the fossilized bodies of ancient plants and microorganisms, and available today in coal, oil, and natural gas. These statistics indicate the astonishing ecological power acquired by our species in the course of its history. Finfacts article, 2008: Global Food Crisis: Malthus, Food Price Surge, Climate Change and a 42% rise in World Population by 2050

The global population, which was expected to stabilize at about 9bn by 2050, is now forecast to rise to 10.1bn by the year 2100, the United Nations said in a report published on Tuesday. The world's population is expected to hit the 7bn level this October, just 12 years after reaching the 6bn milestone.

The UN said growth in Africa will result in a tripling of the population from the current level of 1bn to 3.6bn. In Nigeria, the most populous country in the continent, the report forecasts that the population will rise from today’s 162m to 730m by 2100. Malawi, which has a population of 15m today, could grow to 129m by 2100, the report said.

The report says small variations in fertility can produce major differences in the size of populations over the long run. The high projection variant, whose fertility is just half a child above that in the medium variant, produces a world population of 10.6bn in 2050 and 15.8bn in 2100. The low variant, whose fertility remains half a child below that of the medium, produces a population that reaches 8.1bn in 2050 and declines towards the second half of this century to reach 6.2bn in 2100. For long-term trends the medium variant is taken as reference.

The medium-variant projection for 2050 is more certain than for 2100 because people who will be 40 years and older in 2050 are already born. According to the medium variant, it will take 13 years to add the 8bn, 18 years to add the 9bn and 40 years to reach the 10bn. According to the high variant, an additional billion would be added every 10 or 11 years for the rest of this century.

Today, 42% of the world’s population lives in low-fertility countries, that is, countries where women are not having enough children to ensure that, on average, each woman is replaced by a daughter who survives to the age of procreation. Another 40% lives in intermediate-fertility countries where each woman is having, on average, between 1 and 1.5 daughters, and the remaining 18% lives in high-fertility countries where the average woman has more than 1.5 daughters (see map).

High-fertility countries are mostly concentrated in Africa (39 out of the 55 countries in the continent have high fertility), but there are also nine in Asia, six in Oceania and four in Latin America. Low-fertility countries include all countries in Europe except Iceland and Ireland, 19 out of the 51 in Asia, 14 out of the 39 in the Americas, two in Africa (Mauritius and Tunisia) and one in Oceania (Australia).

The report says because declining fertility and increasing longevity lead to population ageing, population ageing is fastest in the low-fertility countries. Today, 11% of the population of low-fertility countries is aged 65 years or over and just 34% is under age 25. By 2050, according to the medium variant, 26% of their population will be aged 65 or over and just 24% will be below age 25. However, because fertility is projected to increase over the projection period, by 2100 the proportion under 25 increases to 27% and that of those aged 65 or over rises minimally to 28%.

Population ageing is slower among the intermediate-fertility countries, but results in a 2100 population similar in age structure as that of the low-fertility countries. The proportion of the population under age 25 passes from 47% in 2010 to 26% in 2100 and that aged 65 or over rises from 6% in 2010 to 26% in 2100.

Population ageing is slowest among the high-fertility countries, which have still a very young population. In 2010, 62% of their population was under age 25 and that proportion is projected to decline markedly to 48% in 2050 and 35% in 2100. At the same time, the proportion aged 65 or over is projected to rise from just over 3% in 2010 to 6% in 2050 and to 16% in 2100.

The report says that China, which has a one-child policy could see its population peaking at 1.4bn in the next couple of decades, then declining to 941m by 2100.

Meanwhile the United States, which today has a population of 311m,  is growing faster than many rich countries, because of high immigration and higher fertility among Hispanic immigrants will see the population rising to 478m by 2100.

In recent times, the funding of family planning programs have been under attack from the Catholic Church and conservatives in the United States.

An example of the challenges is the experience of  Yemen, a country in an arid region at the bottom of the Arabian Peninsula, which is currently in political turmoil.

The population has quintupled since 1950, to 25m and may rise to 100m by the end of the century; it has to import most of its food and if it had an abundant supply of oil, it could desalinate water but it does not have that flexibility.

Finally, the rising food demand will coincide with global warming, the impact of which will be felt in particular in tropical regions.

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