POPULATION GROWTH

Intro: With population numbers projected to continue to swell over the course of the twenty-first century, there are some pressing questions that remain unresolved. We should turn to science in search of solutions to Earth’s depleting space and resources.

THE subject of global population growth can be an emotive one, and many accounts of rising populations are accompanied by dire warnings of impending catastrophe. Concern about population growth is by no means a modern phenomenon, though. In 1798, the British cleric Thomas Malthus published An Essay on the Principles of Population, in which he addressed the potential problems that could develop due to the rapidly rising population in Britain at that time, a consequence of the Industrial Revolution. He argued that populations had the capacity to grow more quickly than food production, writing, “The power of population is so superior to the power of the earth to produce subsistence for man, that premature death must in some shape or other visit the human race.” It would become a highly influential concept and one that would reach beyond demography alone – acknowledged, for instance, by Charles Darwin as having been one of the key ideas that led to his theory of evolution by natural selection, which described competition for resources as being one of the driving forces behind evolution.

The Population Bomb

In 1968, the American entomologist and environmentalist Paul Ehrlich wrote in Malthusian terms in The Population Bomb of an upcoming catastrophe, in which many millions of people would die of starvation. Though not the first publication to examine the so-called “population problem”, its popularity introduced the issue to a much wider audience. It was followed in 1972 by the even more widely read The Limits to Growth, a collaborative report commissioned by the political think tank the Club of Rome. Both works were relatively sober, informed assessments, but were followed by a range of sensationalist books and articles, containing various prophecies of doom – which remain a feature of environmental discussion today.

Paul Ehrlich, whose book brought the population problem to the attention of a much wider audience.

In The Population Bomb, Ehrlich wrote that the Earth could support two billion people before disaster ensued – a figure that had already been exceeded by more than a billion at the time the book was published. Now, almost 50 years later, the predicted catastrophic collapse has not occurred (at least not yet anyway). In July 2015, the Population Division of the United Nations Department of Economics and Social Affairs in New York released the annual revision to its 2010 population census, providing estimates of the global population over the course of this century. According to this, the global population was 7.3 billion in 2015, and was expected to continue growing, reaching 10 billion by the middle of the century and 11.2 billion by 2100, by which time the rate of growth is expected to have slowed – before stabilising and perhaps beginning to fall.

By no means do all demographers agree with the UN figures. The wide variation between experts’ population predictions is a consequence of the number of unknown factors involved, and because in reality people rarely behave exactly as expected. But, if we take the UN figures as a reasonable estimate, over the next three to four decades an additional 3 billion people will inhabit the world, and the total figure will be five times higher than Paul Ehrlich’s estimated carrying capacity of the Earth.

The Impact of Science

One of the ways science has helped to avert potential disasters is through agricultural research aimed at increasing food produce. One of the best-known examples of this is the Green Revolution on the Indian subcontinent, which began in the 1960s – a period when India and Pakistan were experiencing population booms that appeared to be outstripping the capacity of the region’s agriculture to produce enough food for everyone. New varieties of high-yielding wheat, developed by the American agronomist Norman Borlaug at a research station in Mexico, were transferred to the subcontinent, greatly increasing agricultural productivity and averting the potential for widespread famine.

Subsequent research produced new varieties of other staple crops, including rice, and these, together with the use of new technologies in the shape of farm machinery, fertilisers and pesticides, have had a dramatic impact on the amount of food produced – even if these technical advancements can come with social and environmental costs. It has become clear that new technology on its own is not a complete solution, though, and extreme poverty can lead to people remaining malnourished despite there being no local food shortages, through not having land to grow crops themselves or the means to buy enough food.

Science can also help in the field of healthcare, through the development of medical technology and drugs that address the particular problems causing high levels of child mortality, which are often encountered in those parts of the world where high rates of population growth occur. When such technologies are combined with more widely available healthcare services, the resulting reduction in child mortality often leads to lower rates of population growth. Put simply, women have fewer children in places where those children are more likely to survive into adulthood, and so population numbers gradually begin to stabilise.

Hope For The Future

The UN figures show that growth rates have already slowed down in many parts of the world. Europe, North and South America and Oceania now show no growth at all, and nor does much of Asia, with the notable exceptions of India and Pakistan. About three-quarters of the population growth set to occur over the course of this century is projected to be on the African continent, and this rise will almost all be as a consequence of people living longer, rather than an increase in the number of children being born. This statistic is key to gaining an understanding of how population growth should slow down and eventually stabilise in the future; improvements in healthcare initially lead to a rapid rise in life expectancy, so, rather than a rising population being caused by more children being born, it is actually a consequence of there being an increased number of older people. Over time, the initial rapid increase in life expectancy will tend to level off and, at this point, the population will stop rising as well.

IN the future, then, there will be many more people in the world, and it does appear that population growth is set to continue in the long term. The challenges ahead are to grow enough food, to alleviate extreme poverty and to provide adequate healthcare for the entire global population.

Alternative Theories

UNLIKE the doom merchants who have until recently dominated the public debate on population growth, the Swedish doctor and statistician Hans Rosling describes himself as a possibilist, believing not only that the Earth can support 11 billion people, but that all of them can enjoy a good quality of life. He appears to be on a mission to make population statistics entertaining as well as informative, making use of dynamic graphics to illustrate his lectures and enlivening proceedings with plenty of comical jokes, mostly at his own expense.

To take just one example of many, Rosling describes the washing machine as being one of the great inventions of the twentieth century because of the impact it has had on freezing women from domestic drudgery, allowing them the time to do other things, like going to university or by seeking an alternative career. As he points out, the statistics show that as women become better educated, they gain more control over their lives – over the age at which they start a family and the number of children they have. Where they have the choice, many women opt to have children later in life than their mothers and grandmothers did, and often prefer to have two or three children rather than five or six. This phenomenon has been seen around the world and has often occurred over the course of a single generation. Rosling is not trying to say that this is entirely caused by the washing machine, rather using it to illustrate the point that the empowerment of women has been one of the driving forces behind the observed reduction in population growth rates.