I recently received an email with the challenging pseudo-statistic, "If the population of China walked past you, 8 abreast, the line would never end because of the rate of reproduction." But the really challenging thing is to keep abreast of demographic forecasts. According to a fascinating survey of current trends in the Wilson Quarterly, "the latest UN projections suggest that China’s population, now 1.3 billion, will increase slowly through 2030 but may then be reduced to half that number by the end of the century".

Written by Martin Walker, a well-known British journalist with several books to his credit and now a senior scholar at the Woodrow Wilson Center, the article tears to shreds the newspaper and blog cliches about world population. Although much of it is old news to demographers, it is required reading for anyone who wants to know what is really happening.

Walker’s basic theme is that shifts in fertility slowly make obsolete projections from current population trends. For instance, many people think that high birthrates amongst Muslim migrants to Europe and in North Africa mean that Europe is doomed to become Eurabia. But this doom is far from certain. As Walker points out, there has been a sharp reduction in fertility amongst Muslim immigrants.

"Data on birthrates among different religious groups in Europe are scarce, but they point in a clear direction. Between 1990 and 2005, for example, the fertility rate in the Netherlands for Moroccan-born women fell from 4.9 to 2.9, and for Turkish­born women from 3.2 to 1.9. In 1970, Turkish-born women in Germany had on average two children more than German-born women. By 1996, the difference had fallen to one child, and it has now dropped to half that number."

The reduction in Muslim birthrates in Europe is also happening across the Middle East and North Africa, with the exception of the Palestinian Territories and Yemen. In Tunisia, the United Arab Emirates, Bahrain, Kuwait, and Lebanon, fertility rates have dropped to near-European levels, and Algeria, Morocco and Turkey are following suit.

A startling decline in fertility is taking place in Iran, which Walker describes as "one of the most dramatic demographic shifts in human history". Only 30 years ago, the fertility rate was 6.5 children per woman. It is now 1.7. The consequences of this are immense. Far from becoming a Muslim superpower, Iran will have to cope with an ageing population around the time that its oil runs out.