As the global population hits seven billion, a crowded planet isn't the only challenge: the people of the world are young now, but they are about to age like never before.
The milestone, for a world that only counted four billion souls in 1974, has raised concerns about competition for scarce resources, like fresh water and oil, as the planet's population ticks upward.
But it is how the world deals with young and old that will largely determine how well it squeezes people in, a report by the United Nations Population Fund, the UNFPA, suggests.
The world's population will pass the seven billion mark on Halloween, according to estimates.
And at seven billion, this is a youthful world where those under 25 make up 43 per cent of the population. But it's the older set who will expand the fastest: the number of people over 60 is expected to grow almost threefold, from 893 million to 2.4 billion, by 2050, when the total population of the Earth is expected to be 9.3 billion.
An aging population is old news to Canadians. But the way the world copes with the very different pace of population change in different countries will have an impact here: on the wealth and health of the world we trade and live with, but also on the forces that move people to migrate here. Canada, the report notes, had the fifth-largest number of migrants – people who came from other countries – in the world.
On the one hand, the report argues, the youthful world can be a force for positive developments in the world. "Yet this opportunity of a 'demographic dividend' is a fleeting moment that must be claimed quickly or lost," says the UNFPA report, entitled the State of the World Population 2011.
That's because aging will quickly overtake the youthful state of the world, and the projections differ depending on nation.
Developed countries like Canada largely have low fertility rates, ageing and potentially shrinking populations. Some emerging nations like China are moving from young to old very rapidly. And many of the least developed countries have high fertility rates and young populations – the median age in Nigeria is 18.5 years.
For young, developing nations, the report argues, the future can turn either way. Young populations could fuel growth and a better standard of living, or population growth that leads to misery and outstrips the potential for economic growth, spiralling the standard of life downward.
In some of those countries, lifespans are much longer than decades ago, but many women are married young, often as children under 18 – and as a rule, that leads to very high fertility rates, and different lives. It limits education and life choices for women, more deaths in childbirth and disease, and high birth rates that outstrip economic growth. The report argues that better access to birth control, and less child marriage, would have an impact on their prospects.
So, too, will other trends, like economic growth and urbanization: in Ethiopia, with a rapidly-growing population, the fertility rate is 3.8 children per woman, but in the capital, Addis Ababa, the rate is less than 1.5 – lower than the 2.1 "replacement rate" that would keep the population stable.
But in many other countries, the prospects are very different: as populations age, the challenge is ensuring the quality of life for those over 60, while younger, working-age people become a smaller proportion of the population. And not only in developed countries like those in Europe or North America.
China's economic growth is booming now, but the over 60 population is growing fast, as people live longer and birth-rates have shrunk. Now China is rapidly facing increasing demands for health care and so-called granny flats for older people whose children no longer live with them. "Old age is a growth industry," Ai Xiandong, the director of the Shaanxi working committee on ageing in the southwest Chinese city of Xi'an, says in the report.
The dramatically different growth prospects for different countries could shape the flows of people across the world – the millions who migrate to countries like Canada. Some countries, will depend on those flows for population and labour-force growth, and others, for the money they send back home as remittances. But, the report suggests, the number of people who seek to move, and face difficult choices to leave home and often endure hardship in the hope of a better life, will depend on the economic prospects at home that are shaped in part by their own population trends, as well as the policies of the countries that might receive them.
Campbell Clark