The UN Population Division has determined that the 7 billion world population mark will be reached today, October 31, 2011. This week’s Economist, the Guardian online, and the New York Times have written on this already, and other news media are following suit. Having produced the World Bank’s demographic projections for some years, and now working as a demographer in the World Bank’s Africa Region, let me add my perspective to the mix.
The approximate date of the world reaching the 7 billion mark is no surprise. When the Bank issued demographic projections back in 1985 (linked to World Development Report 1984– the only one in the series to have specifically focused on the demographic aspects of development), the 7 billion milestone was forecast for early 2011. This is quite close to the current estimate, especially when you consider the projection span of 26 years. At the global level, demographic projections are fairly reliable (but less so for individual countries or small regions).
Of course, the exact date of the 7 billion mark is still a calculated guess, as the vast majority of people in the world live in countries that do not fully register births and deaths. So the October 31 estimate is based on an interpolation of estimated and projected data, which could easily vary by a few months.
In recent years, the impact of population on development has been increasingly analyzed using demographic indicators other than the absolute number of people. In fact, absolute numbers are not particularly interesting. For example, we are fairly sure that the 8 billion milestone will be reached around 2025, despite rapidly declining fertility in many countries. We also know that nearly all developing countries are likely to experience population growth in the coming decades, despite rapid declines in fertility.
More attention is now being paid to the age structure impacts of population on development. Analyses of Asian and Latin American countries suggest that a decline in fertility will over time lead to an age structure that has a large proportion of the working-age people in the population. When policies emphasize strengthening human capital and gender equality (among others), such a shift in age structure is linked with additional economic growth, often called the “demographic dividend”.
Globally, the annual number of births has stabilized at about 135 million, and will soon start to decline. Sub-Saharan Africa is the only region that will have larger and larger birth cohorts for many more decades. This makes it more challenging for Africa to capture the demographic dividend.
However, fertility decline has started in African countries too, reflecting a desire for smaller families on the part of couples, as well as increased access to contraceptives. The prospect of a demographic dividend may be an additional incentive to ensure access to contraception, as a means for African couples to achieve their desired family size.