This projection assumes that fertility levels will eventually stabilize around 2.0 children per woman. The study was released to coincide with a gathering of population scientists at the U.N. Expert Group Meeting on World Population in 2300.
The low scenario of world population in 2300 assumes fertility of 1.85 children per woman, while the high scenario assumes fertility of 2.35 children per woman. This would lead to world population levels of 2.3 billion and 36.4 billion, respectively.
The Population Division was careful to point out that the projections are very tentative, given that even slight variations in the fertility levels could result in major changes in population levels. If fertility turns out to be just 2% lower than that of the medium-fertility scenario, for example, population size would stabilize around 8.3 billion.
The report continues the trend in recent years of a steady lowering of the U.N. population projections. The 9 billion level in the new long-range forecasts show a notably smaller future population size than previous long-range projections, calculated at 10-12 billion. According to the Population Division this is primarily due to the recent fertility declines occurring throughout the developing world. It expects this trend will continue.
Almost all the expected population increase between 2000 and 2300 will take place in the less developed regions. Their population is projected to rise from 4.9 billion in 2000 to 7.7 billion in 2300. In the developed regions, population will see only a slight change, from 1.2 billion in 2000 to 1.3 billion in 2300.
Shifts and aging
The medium-level projection also reveals major changes in the distribution of world population. Africa's share would nearly double, from 13% of the world population in 2003 to 24% in 2300. But Europe's share would be almost halved, from 12% to 7%. Asia's share could fall from its 61% level in 2000 to 55% in 2300.
In terms of individual countries, China, India and the United States will still be the most populous in the world. By 2050, India is expected to surpass China in population size and will remain the most populous country thereafter. Yet, the Big Three are expected to account for a declining share of the world population, passing from 43% in 2000 to about 35% in 2300.
Projections also forecast a dramatically older population. The world median age is expected to rise from 26 years today to nearly 50 years in 2300. Overall, the number of people aged 60 years or over would rise from the current 10% of world population, to 38% in 2300.
In developed regions, the share of those 60-or-over could more than double, from 19% in 2000 to 41% in 2300. In the developing countries the figure could more than quadruple, from 8% in 2000 to 37% in 2300.
The most notable change is for the group of people aged 80 or over, who will see their presence rise from just 1% today to 17%. At the opposite end of the spectrum, the share of those under age 15 will fall from 30% in 2000 to 16% by 2300.
This significant aging of world population would mean a large increase in the ratio of dependents (those under age 15 or over 59) to the population of working age (those aged 15 to 59). In the medium scenario, the world's dependency ratio rises from 0.7 in 2000 to 1.1 in 2300. This means there will be more than one dependent per person of working age.
Older first-time moms
New data confirm the U.N. projections. The average age at which women in the United States are having their first child has reached 25.1 years, the Associated Press reported Wednesday. A study released by the Centers for Disease Control and Prevention attributes this trend to a drop in teen births and an increase in the number of women who are putting off motherhood until their 30s and 40s. The average age for a first-time mom in 1970 was 21.4.
In Italy, the average age of a mother's first child is also on the increase, according to the national statistics body, ISTAT. In 2000 the age reached 30.4, compared with 27.5 in 1980, the newspaper Il Corriere della Sera reported Wednesday. The overall fertility level for women rose marginally, to 1.26 children per woman in 2002, compared with 1.25 the year before. But the increase still leaves fertility well below the level needed -- 2.2 children -- to avoid a decline in population levels.
In the United Kingdom, a recent report affirmed that the population will start to fall after 2040, the Observer newspaper reported Dec. 14. The prediction was made by the government's Actuary Department. Another forecast, made by Office of National Statistics, puts at about 22% the level of women choosing not to have children. According to the report, the average British woman married at 23 at the start of the 1980s, compared with just over 28 today.
Japan is also concerned about the lack of little ones. Its fertility rate is around 1.3 children per woman. But efforts by government authorities to stimulate births have failed, the Financial Times reported Dec. 10. Since the late 1990s, Japanese prefectures have organized hiking trips and cruises for singles in the hope of encouraging weddings. The results have been poor. One scheme in Shimane prefecture in western Japan cost $150,000 during three years, but only produced seven marriages and four babies.
Countries with historically high numbers of children are also facing notable declines in fertility. In Ireland the average number of children per family is down from 2.2 in 1986 to 1.6 in 2002, according to census figures reported June 20 in the Irish Independent. Cohabiting couples accounted for 8.4% of all family units last year, more than double the rate of six years earlier. And almost two-thirds of these couples were childless.
In Mexico, the national body in charge of demographic matters, Conapo, has warned of coming problems due to the aging of the country's population. The sector of those aged 65 or over is now only 5% of the population; that figure could rise to 25% by 2050, the newspaper El Heraldo de México reported May 25.
The quintupling of this group represents a radical break with the past. In 1930 the 65-plus age group counted for 3% of the population. It took another four decades to reach 4.3%. From 1970 to now it only rose by 0.7%. The major increase in the elderly population expected in coming decades is due to a combination of an increase in life expectancy and a sharp decrease in fertility. A population boom is indeed on the way, among the elderly.