Bob Walker: The working assumption always seems to be that population growth is a “given,” and that world population will be 9 billion by 2050 and there’s nothing that can or will be done about it.
Projected population growth, however, is just a projection. It’s not a prediction. (Demographers are loath to make predictions). To the extent that demographers talk about the assumptions underlying the UN medium variant, which now shows world population reaching 9 billion, by 2042, there’s a growing consensus that the assumptions may prove too optimistic (i.e. population may grow more rapidly than projected). Reasons for this vary, but it includes declining donor nation assistance for family planning over the past 17 years, a variety of cultural factors (e.g. prevalence of child marriage, male opposition, and misconceptions about the dangers of contraception). For more about the population projections, see this Woodrow Wilson Center discussion.
In particular, listen to the comments made by Carl Haub, the senior demographer at the Population Reference Bureau:
“It has been – I guess conventional is a good word – to assume that birth rates are going to come down the way they did in the rich countries,” Haub noted.
But there has been a “stall” for many developing countries, which he suggests is caused by fast initial uptake from urban women followed by much slower uptake by rural women. These dynamics, however, are relatively new and therefore are not always well incorporated into current projections.
On the other hand, population projections are extremely sensitive to changes in fertility. If the total fertility rate, the average number of children that a woman has in her lifetime, falls by even half a child, the impact on the long run projections is enormous.
Read the full article here: http://dotearth.blogs.nytimes.com/2012/07/11/a-gates-summit-aims-to-fill-a-family-planning-gap/