Global population: From explosion to implosion?

Three unprecedented shifts are taking place in world population. Before 2000, the young always outnumbered their elders: for some years now it has been the other way around. Until now, there have always been more people in the countryside than in towns or cities; within the next few years this will no longer be so.
And since 2003, for the first time, most people have been living in a country or region of the world where fertility is below the strict replacement rate of 2,1 children per woman. In the past 50 years, median fertility has fallen from 5,4 to 2,1.

Six significant developments will stand out in future world population trends, as recently discussed in one of the United Nations Educational, Scientific and Cultural Organisation’s (Unesco) “21st-Century Talks” organised by Jerôme Bindé on the subject Population: From Explosion to Implosion?.

The population growth of the latter 20th century will come to be seen as one of the biggest events in history. Though slowing, this significant increase has by no means come to an end: today’s 6,6-billion can be expected, under the UN’s “middle” scenario, to reach 9,2-billion by 2050.

Secondly, there is an abrupt slowdown in the rate of growth, due to the demographic transition. Taking hold increasingly in the South as well—even in Africa its first signs are to be seen in a number of countries—this transition shows that there is nothing inevitable about population matters. We shall look back on the 20th century as humanity’s apprenticeship: the time when, having delayed death, human beings finally began to take control of life by choosing a family size compatible with their wishes.

The fall in fertility is admittedly very uneven, differing greatly from region to region and from country to country. It is proportional to levels of education and schooling, especially among girls, and to development. Nevertheless, the demographic transition has also been taking place in many countries where women have only limited access to education and employment: television, the demographers tell us, has been fostering a new understanding of women’s condition, and new notions of freedom.

Population growth

Virtually all the population growth between now and 2050 will take place in developing countries. This means we shall be seeing an utter recasting of the demographic map: in 1950, the population of the South was roughly twice that of the North, but in 2050 no fewer than 86% of the world’s people will be living in the South.

Next, if current trends continue, the whole of this population growth will be taking place in towns and cities. The scale of the urbanisation under way at present is gigantic—revolutionary, indeed: the amount of building needed, in less than half a century, is the equivalent of 3 000 cities of a million inhabitants each!

Fifth, world population is marked by radical inequality of various kinds: in the first place, the human population is very unevenly distributed, with 10% of the world’s dry land accommodating more than 60% of its people. Then, life expectancy at birth varies almost twofold between the most developed countries and some of the poorest, such as Sierra Leone or Afghanistan. Infant mortality rates have fallen considerably, but the fall has been much slower in certain Asian countries, and particularly slow in Africa.

Lastly, there is another uneven but generally destabilising trend that will impose an increasing burden: the ageing of the population as a result of lower fertility and higher life expectancy. This will affect different societies in very different ways. In 2050, nearly one person in three in the North will be older than 60, and one in five in the developing countries.

A spectre is haunting the ageing societies of the North: the spectre of depopulation, which could have serious effects on many countries in the next few decades if the numbers are not made up by migration. Furthermore, the world’s richest countries are in danger of a general loss of dynamism, problematic relations between the generations and difficulties in funding their social security and retirement arrangements, to say nothing of ethical dilemmas such as whether to prolong life to the utmost or ensure a decent old age for all.

The South will face the agonising question of how to cope with an ageing population when state-based social protection systems of sickness insurance or pension schemes are absent, yet traditional forms of social and family solidarity are crumbling under modernisation and urbanisation.

It is possible, however, that within a few decades population could begin to implode the whole world over, for there is not the slightest reason to assume that the decline in fertility, once started, will miraculously stop just at replacement level.

Immediate challenges

Meanwhile, there are immediate challenges to be faced. I have just touched on the challenge of international migration, but there is a whole battery of others: food security, jobs, the fight against poverty, public health, housing, infrastructure, the environment and the promotion of sustainable development.

Will there, for example, be enough for everyone to eat in this world where encroaching deserts and sprawling cities are helping to reduce the area of farmland per person, which is expected to fall from 2 800 square metres in the early 1990s to 1 700 square metres in 2025? Even though rising food production has consistently outrun population growth in recent decades, there is no denying that a further “Green Revolution” is needed if the challenges of the future are to be met.

As early as 1795, Condorcet had the exceptional foresight to realise that the danger of over-population, which he saw could lead to a “diminution of happiness”, could be mastered through a rise in productivity, better management, the prevention of waste and the spread of education—especially girls’ education. Realising the threat that population might come to pose to the environment, Condorcet already had an answer: “dematerialised” growth.

“The same level of production,” he wrote, “will be achievable with less destruction of raw produce, or alternatively will last longer.”

Population growth also challenges development itself, however, and hampers the fight against poverty: over the next quarter-century, the countries of the South are going to need to find room for no fewer than a billion new arrivals on the labour market—yet the phenomenon of “jobless growth” is stalking developed and developing countries alike.


Given these challenges, what are our priorities? Only the emergence of real “knowledge societies” holds out any prospect of coping with population growth and ageing. We have no choice but to work for equitable growth and development founded on intelligence, science, technology and a change in our ways of living, producing and consuming. The greatest priority of all will assuredly be education.

Basic education is first and foremost—especially the education of girls, the best contraceptive of all. According to one study, there are regions where girls are excluded from secondary schooling and the women have an average of seven children each. Where girls’ school enrolment is just 40%, this mean figure falls to three.

Life-long education for all ought to be recognised as an essential priority as well, for this is the answer to ageing populations and rising life expectancy. As knowledge and skills become outdated more rapidly, and people face the need to keep up by retraining or changing occupation, the demand for education is increasingly going to become a life-long matter. At bottom, this is good news: the world population will become older, admittedly, but individual humans will spend more of their lives in what counts as “youth”—for they will never stop learning.

Koïchiro Matsuura is director general of Unesco

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