Paul Ehrlich and Anne Ehrlich, New Scientist 25 Sep 09;
GLOBAL population growth has slowed significantly, but it hasn't stopped. By 2050 there may be about 35 per cent more people on Earth than there are today. We are already seeing increasing shortages of food, water and other resources and growing numbers of hungry people.
Yet to embark on any discussion about limiting our numbers is to enter sensitive and controversial territory. Perhaps this is not surprising, as in the 1960s, when population growth became an issue of widespread concern, the discussions often had a racist undertone, in which the "well-off" focused on the exploding populations of "underdeveloped nations".
Nowadays it is understood that the key population-related issue is the destructive pressure human activity is exerting on our life-support systems, posing a growing threat to the sustainability of civilisation. Of course, this is not all because of human numbers; it also has to do with how much each of us consumes. That's why, in our view, the US with its population of over 300 million and high per capita consumption should be seen as Earth's most overpopulated nation. It is also why the emergence of "new consumers" constitutes a major additional assault on global life-support systems. Moreover, the 2.3 billion people likely to be added to the human population by 2050 will undermine those systems much more seriously than did the previous 2.3 billion, as each additional person will, on average, have to be supported by scarcer, lower-quality resources imposing ever greater environmental costs.
Yet many people still assume that humanity will easily manage to support more than 9 billion people in 2050 and beyond. Such confidence ignores some grim possibilities. There are only two ways by which population can stop increasing: a falling birth rate or rising death rates. We have already seen a rise in death rates in southern Africa and Russia, and there may well be further increases in death rate ahead, especially as disruption to the global climate increasingly destabilises agricultural systems. Even today, more than a billion people are going hungry.
The environmental deterioration resulting from ever more people consuming ever more resources will place the heaviest burdens on those least able to cope, as the great majority of those additional billions of people will be in the poorest nations, where poverty and high birth rates are inextricably linked. Uganda's population, for example, is predicted to almost treble by 2050, growing from around 33 million today to 91 million in the next 40 years. Rapid population growth undermines development efforts. The resulting poor education, lack of public health facilities, and inadequate infrastructure in turn foster high birth rates.
Yet the priority given to population issues has diminished compared with concerns about development. If population growth continues unabated, we fear the problems of development will be "solved" by rises in death rates. For this reason, efforts to slow population growth should be treated as a human rights issue.
The way to reduce fertility rates is well known. It involves a cultural shift towards improving the education and status of women, making family planning and safe abortion more widely available, and moving towards a world where every child is a wanted child.
Nearly all developing countries have family planning programmes, but they are badly in need of renewed support. There has to be a recognition, at the highest political level, of the importance of reducing birth rates both as a pressing human rights issue and as a proven contributor to successful development.
This has to be linked to family health and welfare programmes, to education (especially for girls) and to the opening up of opportunities for women to participate in their nations' economies. An example of what can be achieved is provided by the Grameen bank, which offers credit to the poor people of Bangladesh, especially women, and has no doubt helped reduce birth rates there simply by boosting grassroots economic development.
Somehow, cultural attitudes toward large families everywhere need to be changed. It should be considered immoral to have excessive numbers of children - an attitude that already exists in most industrialised nations with low birth rates. Nothing is more clearly a governmental responsibility than keeping a nation's population size sustainable by benevolent measures.
As well as curbing population growth, we shouldn't forget the pressing issue of excessive consumption by the rich. Humanity needs to get behind a global discussion of these issues, perhaps through a framework we have devised called the Millennium Assessment of Human Behavior (http://mahb.stanford.edu). This is a forum for global discussion of key ethical and cultural issues related to the human predicament. A major element of that discussion must be how to end the growth of the total human population humanely and begin a slow decline similar to the one that has so fortunately started in Europe and Japan. If that can be done, then a sustainable future for civilisation might be possible.
Days when the world has shrunk
The inexorable rise of the human population has been the dominant theme of our planet for centuries. In recent history, days that we know to have ended with fewer people than they started with are extremely rare.
The most recent was 26 December 2004, when the Indian Ocean tsunami killed nearly 250,000 people. Another 160,000 died that day of other causes, and the day's 370,000 births couldn't compensate, according to environmentalist Robert Engelman in his book More.
You have to go back to the 1970s to find other days of world population shrinkage, such as the Tangshan earthquake in China on 28 July 1976 and the devastating cyclone that hit Bangladesh on 12 November 1970, both of which killed at least 250,000 people. Even China's great famine of 1958 to 1961, which caused around 15 million deaths, dented rather than stalled world population growth.
Further back in time, the 70,000 deaths caused by the atomic bomb dropped on Hiroshima, Japan, on 6 August 1945 outweighed the population growth of around 60,000 people that would otherwise have taken place that day. With a lower death toll, the same probably isn't true of the bombing of Nagasaki three days later. Even a particularly bad day during the first world war, such as 1 July 1916 when the British alone lost around 20,000 men at the battle of the Somme, probably didn't stall the world's upward population trend. However, the flu pandemic of 1918 to 1920, which killed about 50 million people, almost certainly did.
The biggest hit to world population in (relatively) recent times is the Black Death of the 14th century, which killed perhaps 75 million people and reduced Europe's population by 30 per cent.
Things will be very different in the future. There will still be disasters and wars, of course, but some time after 2050 the world will enter a new era when the population will shrink on many days. We will simply be having fewer children.
Alison George
Paul Ehrlich is an ecologist and evolutionary biologist who became a best-selling author with his 1968 book The Population Bomb. He is now professor of population studies at Stanford University, California.
Anne Ehrlich has co-authored several books with Paul, and is a director at the Center for Conservation Biology at Stanford
