From the Population Council:
What’s next? Population explosion or decline?
Will recent declines in fertility rates lead to a “birth dearth”? Has the “population explosion” been defused?
These simple questions are not simply answered and should be put into a proper perspective, says Population Council demographer John Bongaarts. Current trends in reproductive behavior differ sharply between regions and should not be confused. “In the already crowded developing world, despite plummeting fertility rates, both the number of births and population size will keep growing,” he says. “The expected addition of several billion more people will hamper ongoing efforts to reduce poverty and achieve sustainable development.”
“On the other hand, in parts of the developed world, particularly Europe and Japan, already low fertility is causing consternation over the potential adverse effects of an aging or declining population. This concern should not be overblown, however, since reported fertility measures do not reflect the fact that couples are still having about two children—they’re just having them later in life. Fertility rates are not as low as they appear to be,” Bongaarts explains.
The world is only at mid-point in population growth
Bongaarts pointed out in a recent issue of Science that contraceptive use in the developing world, once rare, is now widespread: the average number of births per woman has fallen by half—from the traditional six or more to near three today. This “revolution in reproductive behavior,” says Bongaarts, has led some to speculate that “the world population explosion is over.” But instead of being near the end of the “explosion” with today’s population of 5.9 billion, Bongaarts comments, “we are just past its mid-point. After a record-breaking increase of 2 billion people over the past 25 years, the same increase is projected over the next 25 years.”
Large increases in population growth are expected in Africa, Asia, and Latin America** yeah, but Akats and dhanosn say otherwise - who to believe?** for three reasons, Bongaarts says: Fertility is still about 50 percent above the two-child level needed to bring about population stabilization. With more than two surviving children per woman, every generation is larger than the preceding one.
Declines in mortality—historically the main cause of population growth—will almost certainly continue. Higher standards of living, better nutrition, and expanded health services have increased life expectancy by 50 percent since 1950. The unhappy exceptions will be life expectancy declines in sub-Saharan African countries with severe AIDS epidemics.
The historically largest generation of women about to enter the childbearing years will produce more than enough births to maintain population growth for decades even if they each have only two children—the result of population momentum.
Not a birth dearth, either
Europe, North America, and Japan face quite a different demographic future, Bongaarts says, along with such rapidly developing Southeast Asian countries as Hong Kong, Korea, and Singapore, which also have experienced steep declines in population growth rates since 1960. But because of immigration, rising life expectancy, and population momentum, the populations in even these countries are projected to remain close to current levels for several decades, with modest increases expected in some (e.g. the U.S.) and small declines elsewhere (e.g. in Europe).
Bongaarts feels that concern about underpopulation in developed countries has been exaggerated. Although observed fertility has reached historic lows in many developed countries and the percentage of women remaining childless is relatively high, it is likely that birth rates will not drop further and may even turn up. To support this conclusion, Bongaarts points to a puzzling discrepancy between expressed preferences for family size and measured fertility in most low-fertility societies.
In most low-fertility societies, the preferred family size is about two children and the actual childbearing experiences of women support this number, but this is not reflected in the most widely reported measure of annual fertility (the so-called total fertility rate). “The measurement of this fertility rate picks up a slightly different picture than we get looking at women’s actual reproductive histories,” Bongaarts says. If women in a given country have the same number of children in their lifetime, but later in their lives than their predecessors, this will appear to be a reduction when we look at annual birth statistics. Family size may in fact not be changing in nearly as dramatic a fashion as is suggested by the year-by-year aggregate birth statistics.
“These distortions,” comments Bongaarts, “are temporary because they exist only while the age at childbearing is rising. Once women stop deferring births, the distortion disappears and the very low fertility rates observed in the developed world should rise closer to the two children most couples want.”
page modifed Nov 1, 1999
“All rising to a great place is by a winding stair.” F.Bacon
Brille
