Jean Raspail’s 1973 dystopian novel The Camp of the Saints is being played out piecemeal in the Mediterranean this year with enormous numbers of African and Middle Easterners trying to make it to the wealthy north side of the sea.

A new paper in Science fiddles with UN population forecasts to make them more statistically sophisticated and, holy cow, there are a lot of babies in Africa:

World population stabilization unlikely this century Patrick Gerland et al. Science, forthcoming Abstract: The United Nations recently released population projections based on data until 2012 and a Bayesian probabilistic methodology. Analysis of these data reveals that, contrary to previous literature, world population is unlikely to stop growing this century. There is an 80% probability that world population, now 7.2 billion, will increase to between 9.6 and 12.3 billion in 2100. This uncertainty is much smaller than the range from the traditional UN high and low variants. Much of the increase is expected to happen in Africa, in part due to higher fertility and a recent slowdown in the pace of fertility decline. Also, the ratio of working age people to older people is likely to decline substantially in all countries, even those that currently have young populations.

Most of the anticipated growth is in Africa, where population is projected to quadruple from around 1 billion today to 4 billion by the end of the century. The main reason is that birth rates in sub-Saharan Africa have not been going down as fast as had been expected. There is an 80 percent chance that the population in Africa at the end of the century will be between 3.5 billion and 5.1 billion people. Other regions of the world are projected to see less change. Asia, now 4.4 billion, is projected to peak at around 5 billion people in 2050 and then begin to decline. Populations in North America, Europe, and Latin America and the Caribbean are projected to stay below 1 billion each.

From Science Daily: Above I’ve used Google to plot Total Fertility Rates (projected babies per woman per lifetime) for the three most populous countries in Africa. The TFR in Ethiopia has been falling, but is still well above 4. In Nigeria and Congo, its at six.

The concept of Demographic Momentum needs to be understood. Say that tomorrow, the TFR in Nigeria and Congo instantly dropped from 6 to the replacement level of 2. Would the population stabilize immediately? Not for many decades. You see, the women who are having six children today would still wind up having 12 grandchildren, whereas in a country where the TFR has been stable at 2 for a generation, mothers can expect to have four grandchildren eventually.

But in both Nigeria and Congo, there really hasn’t been a trend toward substantially lower TFRs over even the last half century.

Environmental reporter Andrew Revkin writes in the New York Times:

Yeah, logic is racist.