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Three UN scenarios for population

Population Bombshell Fred Pearce NS 11 Jul 98

FOR the past million years, the world's human population has grown almost continuously. But demographers have identified three great population surges, each following technological revolutions that dramatically increased the number of people that the world could sustain. The first revolution was the invention of tool making, which occurred gradually around the world between a million and 100 000 years ago. The second revolution was the invention of farming. This began at the end of the last ice age 10 000 years ago and spread from core areas such as the Middle East. Agriculture helped the world's population rise from less than 10 million to about 150 million at the time of Christ and 350 million a thousand years ago. But in the 14th century, the number of people in Asia and Europe dropped as a result of the Black Death-an epidemic of bubonic plague carried by fleas on rats-which spread from Asia to Europe. it reduced Europe's population by a third during the 14th century. But recovery followed and by the early 19th century the third great technological revolution, the industrial revolution, was under way in Europe. Its progress around the world continues today. This third revolution has already raised the world's population to around 6 billion, six times what it was at the start of the 19th century, three times what it was in 1930a single life span ago-and almost twice what it was in 1960. And the population may reach 10 billion before, as demographers predict, it stabilises. The key features of this revolution have been advances in food production that have allowed the world to feed more people and new methods of controlling diseases that have allowed people to live longer. Demographers have attempted to describe the progress of the current surge in the world's population with a model called the "demographic transition". This transition classically begins with a rise in life expectancy and consequent fall in death rates, as the health and wellbeing of a society is improved by better health care, hygiene and nutrition. For a time, birth rates remain high while death rates fall, causing a surge in population. But eventually social changes bring about a decline in the birth rate and the population stabilises again.

Middle scenario sees population approaching stability everywhere in the next 50 years
with the dramatic exception of Africa.

A change of pace Prosperity for stability

THE TRANSITION described well the progress of the first countries to industrialise. In Europe the declining death rate (from more than 30 deaths per thousand people each year to below 10 today) took place gradually, beginning in the 17th century and continuing at a slower pace to the present. Around the start of the 20th century, population growth rate in Europe peaked at around 1.5 per cent per year before beginning to fall as people chose to have smaller families and gradually adopted modern methods of birth control. The move to smaller families reflected social changes. In poor rural societies, children were vital as labour in fields and as carers and providers for their parents in old age. But in richer urban societies, they became an economic drain, costly to educate, clothe and feed. Now, as child death rates fall, people are more confident that their children will survive to adulthood, while state pensions and welfare provisions mean that children are not essential to a happy old age. People can invest in material goods rather than children. The whole demographic transition has taken around three centuries in European countries. But it is taking place much faster in many developing countries today, especially in East Asia, where it is being telescoped into a few hectic decades during which national population growth rates have often exceeded 3 per cent per year, causing populations to double in less than 25 years and reducing the mean age of national populations to as low as 15 to 18 years. This is partly the result of the transfer of ready-developed Western technologies that have accelerated medical improvements and economic change. But it may also reflect the adoption of dominant Western attitudes to things such as family planning, and the improved social status of women. As the industrialised countries have reverted to more or less stable populations, 85 per cent of the world's population growth in the past 50 years has been in the developing world. But population growth rates are now declining fast in many developing countries, especially in the rapidly industrialising nations of East Asia, where increasingly rich and urban populations seek to reduce family sizes. Countries such as China and South Korea have halved their population growth rates in 20 years. Progress has been slower in southern Asia. In India, for instance, death rates halved between 1945 and 1970, while birth rates remained almost unchanged, causing the population to double. India's fertility rates-the number of births per woman-have since begun to fall, to an average of 3.5 children per woman today, according to the Washington based Population Reference Bureau. However, in neighbouring Pakistan the average is 5.6 children, the highest in Asia.

Fertility rates in Nigeria are expected to decline from a very high 6

The great divide Rich and poor

COUNTRIES in Sub-Saharan Africa lag even farther behind, with very high population growth rates. Here, improved health care and hygiene have raised life expectancy, but in largely poor rural societies there is little incentive to reduce family sizes. In many African countries average families still have six or more children, while in Kenya in recent years there have been four times as many births as deaths. The country has had the world's fastest population growth rate, exceeding 4 per cent per year during the 1980s. At the United Nations population conference in Cairo in 1994, 28 countries reported that their fertility rates had risen since the previous population conference in 1984. Twenty of those countries were in Africa; others included Pakistan and the US (where the fertility rate rose from 1.9 to 2.1 largely as a result of the immigration of Hispanics with a higher birth rate). Demographers say they no longer see the demographic transition as an inevitable process. Some pessimists argue that countries stuck in the poverty trap will be unable to provide the social conditions that encourage people to reduce their family sizes without an unacceptable degree of compulsion. They point out that during the 1970s and 1980s much of the progress in stabilising the world's population growth rates occurred in China ' where the one child policy-which reduced the annual population growth rate to 1 per cent, the lowest in the developing world-has at times been pursued at the expense of basic human rights. On the other hand, in the 1990s, some of the poorest, least industrialised and least urbanised countries have made the biggest strides in reducing their population growth rates without compulsion. For instance in Bangladesh, one of the poorest nations on Earth, 40 per cent of fertile women use contraceptives, which are provided free by the government. There is a worldwide decline in fertility except in parts of two regions: the M ' iddle East and tropical SubSaharan Africa Some nations appear to be in the process of overshooting the return to stable populations. Having completed the demographic transition, most European countries now have birth rates too low to maintain their existing populations. The average fertility rate in Europe is now 1.4.

There is a long time lag in the translation of smaller family sizes into lower rates of national population growth. People born today will only have children in 20 to 40 years' time. So, if birth rates in a country peak now and then start to decline, the very large number of females born today will still be fertile and having babies until around the year 2040. Any continuing increase in life expectancy will exacerbate the delay.

Young growing middle bulge and aging populations.

1: Population distribution Some highs and lows

DESPITE the massive growth in the world's population over the past two centuries, the parts of the planet that were most densely populated before the industrial era beganEurope and eastern and southern Asia-are generally still the most densely populated today. The Americas and Australia remain relatively thinly populated outside large cities such as Los Angeles, Mexico City and Sydney. Africa too remains comparatively underpopulated, despite pockets of high density along the West African coast, Egypt and the highlands of east Africa. But as the populations of other countries stabilise, Africa's is expected to continue rising rapidly for some decades. its population growth rate is now the world's highest. In 1996, for the first time in recorded history, it had more people than Europe. And the UN's projections suggest that Nigeria's population will triple to 340 million. Overafl,the continent's population is projected to quadruple before it becomes the last region of the world to reach a stable population. As the world's population has grown, millions of people have migrated from densely populated areas to seek new lands and opportunities or to escape poverty or persecution. The greatest migration was from Europe, the Old World, to the New World of the Americas. At the height of the migration, in the first half of the 19th century, two-thirds of migrants were from Britain and a quarter from Germany. In the second half of the century most came from Ireland, Italy, Spain and Eastem Europe. Britain also colonised another "new" continent, Australia, treating it initially as a penal colony. Smaller numbers of people moved temporarily to govern other European colonies and imperial territories. Some people were forced to migrate, most notably the 15 million slaves transported from Africa to the Americas before 1850. European colonialists also transported Indians to East Africa, Malaya and the islands of the Caribbean and Pacific. Other people migrated to escape persecution or famine. This category includes Jews fleeing the Russian pogroms in the 19th century or the Nazis in Germany in the 1930s, and the mass exodus from Ireland during the potato famine of the mid-19th century. During the 19th century there were large movements of people within countries then being "opened up". Millions of people moved from the eastern seaboard of North America to the empty lands in the west, and from European Russia east into Siberia. In the first half of the 20th century the expansion of the Soviet empire brought millions of Russians into central Asia, Siberia and the Russian far east, and into the Baltic and central Europe. The dissolution of the colonial empires of the European powers also triggered new movements. Britain encouraged Caribbeans and South Asians to come to work in Britain during the 1960s, and many North and West Africans moved to France. The 1990s have seen further mass migrations as more than a million people flogded out of Eastem Europe after the collapse of the Soviet empire. During the 1991 Gulf crisis, S million foreign workers in Iraq, Kuwait and Saudi Arabia returned to their homes in Egypt, Jordan, Yemen and the Indian subcontinent. Meanwhile, civil wars and persecution forced Rwandans to flee into Zaire and Tanzania, and Iraqi Kurds to enter Turkey, while a continuing stream of Mexicans and other central Americans moves, often fllegauy, to the US. Many migrants, notably the Chinese in Asia and North America, have achieved dominant places in their hosts' economies. Even so, developed countries are trying harder to keep out those whom they regard as "economic" refugees, looking for a better life rather than fleeing persecution.

2: Women take control

MOST developing countries around the world now have policies intended to slow population growth. The major exceptions indude a handftd of Catholic nations, such as Chile and Argentina, whose governments oppose most methods of artificial birth control-though Catholic Italy and Spain have the world's lowest fertility rates at 1.2 and 1.15 children per woman respectively. Many Islamic nations also remain committed to increasing their populations. Some of the latter, including Saudi Arabia, Sudan, Iraq and Lebanon, boyc the UN population conference in Cairo in 1994 to make their opposition plain. Even so, worldwide about 55 per cent of women of childbearing age now use contraception, says the UN Population Fund. Which method they use depends on a complex mix of government policy and social circumstances. In China and Cuba, governments pressure women to have intrauterine devices (IUDS) fitted, whereas most German women take the pill. Elsewhere men take the lead-in Japan, the condom is king, while Britain has the highest proportion of men in the world with a vasectomy. in TUrkey, government statistics show that withdrawal is the preferred method. in some countries a wide range of methods is freely available. But in East Asia, this is often not true. In China, which has the highest rate of contraceptive use in the world, 90 per cent of women use the IUD, and across Asia as a whole, half of all contraception is by sterilisation.

Slow to show A lifetime of change

THIS time lag is evident today in the postwar "baby boom" generation in Western Europe. Populations continue to rise in man .y countries even though fertility rates are well below the long-term replacement level. For instance, Britain's fertility rate has been below 2.1 for 30 years, but the actual population is not expected to start failing for some years yet, while Western Europe's population is not expected to stabilise until after 2010. In the meantime, the residual population increase will be the outcome of two trends: a rise in the old population and a decline in the young population. In China, the time lag is even more marked. If all couples have two children from now on, the present population of around 1.2 billion will still grow to 1-6 billion by the late 21st century We can clearly see the time lag in global demographics too. The fertility rate peaked in 1950, when each woman had an average of five children. Since then, it has fallen to just 2.9 children. But it was not until the 1990s that the net annual increase in the global population actually began to fall. The net effect of these different national rates of population growth, reflecting the different places of nations along the demographic transition, has been a surge in the growth of the world's population that now seems to have passed its peak. The annual addition to the world's total population peaked at the start of the 1990s at around 90 million a year. But since then it has been declining, to just 80 million a year by 1996. On the basis of national trends, demographers estimate that the world's population will stabilise at around 10 billion in the second half of the 21st century. The population time bomb, it is said, is being defused. Some demographers see no reason why the world's population should reach a steady state since more than 50 countries in Europe, the Caribbean and the Far East, including China now have birth rates below replacement levels and many more could follow. The UN's "low range" estimate of future population trends (see Figure 1) suggests the world's head count could peak at 8 billion in around 2045, before starting to fall, perhaps to below current levels by the end of the 21st century. The Australian demographer John Caldwell, then president of the international Union for the Scientific Study of Population, said at the 1994 UN population conference in Cairo that he believed that this was the most likely scenario. "The experience of the past 20 years," he said, "makes it much more likely that we will end up with a declining population." One of the most important consequences of a dramatic worldwide slowdown in the rate of population growth is a rapidly increasing proportion of elderly people. in the first half of the 1990s, the world's population grew by 1.5 per cent per year, but the number of elderly people grew by 2-7 per cent per year. The average age of a world citi zen is now 28 years. Only 9 per cent of the population is over 60 years, while 32 per cent are under 15. By 2050, projections put the median age at 38, with more than 17 per cent above 60 years old-very similar to the current position in West ern Europe. China's plunging birth rate means that the proportion of elderly people is rapidly increasing. It will have reached Western European levels within 35 years, by which time it will have a higher proportion of elderly people than any other society in history. In Europe the surge in the numbers of old peo ple is already putting pressure on health services and pension funds, while Japan is predicting slower economic growth because of its ageing population. But the impact will soon be felt in developing countries, too. Some demographers now warn that a rapid decline in the growth of the world's population could be worse than a moderate decline, because of its inevitable corollary-a rapidly increasing proportion of elderly people.

Malthus, Marx and Co Radical alternatives

MODERN theory on the relationship between population, economics and the environment begins with the British economist Thomas Malthus. His An Essay on the Principle of Population was first published in 1798, a time of social unrest in the aftermath of the French revolution. This extremely pessimistic work declared that if unchecked human population would grow geometrically (1, 2, 4, 8, 16 and so on), while the food supply could only grow arithmetically (1, 2, 3, 4, 5 ... ). Seeing no means of restraining population growth, he concluded that it could be halted only by hunger and rising death rates among the poorer classes. His tract was an assault on socialism, and Karl Marx decried it as a "libel on the human race". Marx accepted that there was overpopulation but blamed it on an economic system that valued capital over people. Modern environmentalists have revived many Malthusian ideas. In 1968, the US ecologist Paul Ehrlich wrote in his polemic, The Population Bomb, that "hundreds of millions of people" would starve to death because of overpopulation before 1985. Similarly in 1972, the Club of Rome, an influential group of industrialists and intellectuals, used computer simulations to argue in The Limits to Growth that there would be a catastrophic collapse of popu lation in about 2025 as pollution increased and resources ran out (see "Mission Earth", Inside Science, No. 106). Social analysts have since pointed out that it is poverty and insecurity that drive people to have large families. They have argued that social and economic advances can and do reduce population growth rates, as the demographic transition shows. Pop ulation academics, such as the American agriculturalist Frances Moore Lappe have gone on to argue that the high population growth rates in the modern world are a result of the abuse of the human rights of the poor. Pessimists such as Ehrlich have coun tered with the argument that the rapidly growing populations of many of the world's poorest nations are destroying natural resources such as soils and forests so fast that they will never be able to create the social and economic advances that would put a brake on population growth. They envisage a Malthusian crisis overtaking first individual nations and then the world. But a radical alternative to the Malthusian vision was offered by the Danish economist Ester Boserup in her 1965 book, The Conditions of Agricultural Growth. While Malthus argued that agricultural output ultimately limited population levels, Boserup says that population growth drives technological advances that raise agricultural output and create wider economic development. This idea has been taken up by right-wing economists, such as Julian Simon of the University of Maryland, who argues that although population growth means there will be more mouths to feed, it also means there will be "more hands to work and more brains to think".

3: Flight to the cities

WITHIN countries, many of the largest migrations have been from country to town. Over the next 30 years, demographers expect that for the first time most of the world's inhabitants will live in urban areas. People are "pushed" from the countryside by the mechanisation of farming and environmental decline, and "pulled" to cities by jobs in new industries and government investment in services such as schools, hospitals and roads, which are often concentrated in cities. Megacities, cities with more than 10 million people, have come to dominate life in many developing countries. Mexico City, Sdo Paulo, Shanghai and Bombay each have around 16 million people-more than twice the population of London. Tokyo, the most built-up region in the world, has 27 million people. After a generation of very rapid growth, however, the growth of megacities has slowed in the past decade. A 1996 UN conference on the world's living places, Habitat II, heard how many services have collapsed, causing gridlock, air pollution, crime and urban squalor. Many of these cities' inhabitants live in giant shanty towns. However, only 3 per cent of the world's population live in megacities. In most countries, other smaller cities and urban areas are now growing fastest.