photo: wonderjunkie/Creative Commons
The following piece by Robert Engelman is cross-posted from Solutions.
The widespread assumption that world population, now at 6.9 billion, will inevitably grow to 9 billion by midcentury is wrong. The equally widespread belief that an earlier, lower population peak would require coercive "population control" is also incorrect. Population growth rates and average family size worldwide have fallen by roughly half over the past four decades, as modern contraception has become more accessible and popular. Population could peak before then and at a lower level, ameliorating environmental risks associated with climate change, water scarcity, biodiversity loss, and food and energy insecurity.Don't Take Demographic Projects At Face Value
Those who ponder humanity's future in the twenty-first century generally take at face value demographic projections suggesting that the world population will reach something like 9 billion around 2050 and will then stabilize at about that level. The widespread belief that this 30 percent increase from today's 6.9 billion people is inevitable undermines consideration of the role of population size in climate change, water scarcity, biodiversity loss, rising energy prices, and food security. Contributing to this is the related view that efforts to prevent population growth would require coercive government policies that constrain couples from having the children and the family sizes they want. While some analysts are confident that the world can feed, house, and otherwise support 9 billion or more people, others are less certain, and voices of caution about population growth are heard more often than in the past. A logical application of the precautionary principle in the face of current environmental problems would suggest that humanity could more easily accomplish these feats in an environmentally sustainable manner with a smaller population.
In a joint statement in 1993, representatives of 58 national scientific academies stressed the complexities of the population-environment relationship but nonetheless concluded, "As human numbers increase, the potential for irreversible changes of far-reaching magnitude also increases. ... In our judgment, humanity's ability to deal successfully with its social, economic, and environmental problems will require the achievement of zero population growth within the lifetime of our children." In 2005, the United Nations' Millennium Ecosystem Assessment identified population growth as a principal indirect driver of environmental change, along with economic growth and technological evolution.
In October 2010, a group of US and European climate and demographic researchers published findings from an integrated assessment model calculating the impact of various population scenarios on fossil-fuel carbon dioxide emissions over the coming century. If world population peaked at close to 8 billion rather than 9 billion, along the lines described in a low-fertility demographic projection published by the UN Population Division, the model predicted there would be a significant emissions savings: about 5.1 billion tons of carbon dioxide by 2050 and 18.7 billion tons by century's end.
What if we could prove wrong the popular conviction that a future with 9 billion people and a growing population is inevitable? Suppose we could demonstrate that world population size might peak earlier and at a lower level if government policies aimed not at reproductive coercion but at individual reproductive freedom? Suppose such policies aimed to help all women and girls prevent unwanted pregnancies and conceive only when they want to bear a child? This article presents new data on births resulting from women's active intentions to become pregnant. The hypothesis it probes may appear counterintuitive: if, starting at any moment, all pregnancies in the world resulted from each woman's intent to give birth, human population would immediately shift course away from growth toward decline within a few decades.
- Even though most women of reproductive age now use contraception, we are far from a world in which all births result from intended pregnancies. Based on survey data, approximately 40 percent of pregnancies are unintended in developing countries, and 47 percent in developed ones.
- More than one in five births worldwide result from pregnancies women did not wish to occur.
- An estimated 215 million women in developing countries have an unmet need for family planning: they are sexually active, don't want to become pregnant, and yet for various reasons--including lack of access--are not using contraception.
- If all births resulted from women actively intending to conceive, fertility would immediately fall slightly below the replacement level; world population would peak within a few decades and subsequently decline.
- Assuring that all women are fully in control of the timing and frequency of childbearing is not expensive. Religious, cultural, and political opposition to contraception or the possibility of population decline is the key obstacle to such assurance. More research and a public better educated about sexuality and reproduction could engender a global social movement that would make possible a world of intended pregnancies and births.
- TOTAL FERTILITY RATE: Refers to the average number of children a woman would bear over her lifetime if at each point in her reproductive age she had the number of live births typical of women at that age. Note that the total fertility rate differs from the population growth rate, which is the percentage by which a population grows each year, and from the birthrate, which is the number of live births each year per thousand people in the population. The global total fertility rate currently stands at 2.53 children per woman.
- REPLACEMENT FERTILITY RATE: Refers to the total fertility rate in a population that, if held steady over time and absent net migration, would result in a nonchanging population. This rate is often mischaracterized as uniformly and precisely 2.1 children per woman, but not all children survive to reproductive age, and the proportion of those who do not varies over time and by population. For the world as a whole, with many low-income regions still experiencing high death rates among young people, the replacement fertility rate currently stands at 2.35 children per woman. Surprisingly, the gap between global total fertility and replacement fertility is now less than one-fifth of one birth.
Even achievement of global replacement fertility would not stop population growth for several decades, due to population momentum. This is the tendency of a population, influenced by its age structure, to continue its current growth dynamic even as fertility changes. Because there are so many young people of reproductive age in any population that has had above-replacement fertility for some time, for example, even low fertility can produce an overall number of births that statistically overwhelms deaths among the smaller cohorts of older individuals. It can take decades before subreplacement fertility actually halts growth. If total fertility falls well below replacement however, this momentum is weakened and a peak in population will come sooner, followed by a decline. These demographic phenomena are evident in Japan, with a total fertility rate of 1.3 children per woman and a population that has already peaked and is now slowly shrinking.
An Ethical Basis for Action to Slow Population Growth
What can societies that value democracy, self-determination, human rights, personal autonomy, and privacy do to include demographic change among strategies for environmental sustainability? An important answer may lie in a relatively untested set of principles adopted by almost all the world's nations at a 1994 UN conference held in Cairo. The third of three once-a-decade governmental conferences on population and development, it produced a program of action that abandoned the strategy of "population control" by governments in favor of a focus on the health, rights, and well-being of women.6 An operating assumption of this program is that when women have access to the information and means that allow them to choose the timing of pregnancy, the intervals between births lengthen, average family size shrinks, and teen births become less frequent. All of these improve maternal and child survival and slow population growth.
Experts disagree on how reproductive autonomy compares with other strategies in slowing that growth. Some assume economic growth is the most effective means, although birthrates rose along with prosperity in many countries after World War II and remain relatively high in several wealthy oil-exporting nations in which women have fewer rights and lower status than men. Moreover, some analysts argue that the arrow of causation operates more in the other direction, with low fertility stoking economic growth.
There is a more robust and demonstrable correlation between female educational attainment and fertility. Worldwide, women with no schooling have an average of 4.5 children, while those who have spent at least a year or more in primary school have just three. Women who complete at least a year or two of secondary school have 1.9 children--well below replacement fertility rates. With one or two years of advanced education for women, average childbearing rates fall even further, to 1.7. On this basis alone, those interested in depressing population growth rates might want to focus on improving women's educational attainment.
Questions remain about whether education alone can bring about declines in fertility without other supporting conditions, especially easy, affordable access to a range of contraceptive options. Similar uncertainties cloud understanding of exactly how improved child survival and the empowerment of women affect fertility. Improving both factors certainly contributes to later births and smaller families and is valuable regardless of its demographic impacts. But without clear data on the magnitude of these influences, interventions related to schooling, child survival, and women's empowerment are rarely seen as core aspects of governmental population policy.
This brings us to family planning. Access to safe and reliable contraception has exploded since the mid-twentieth century. An estimated 55 percent of all heterosexually active women worldwide now use modern contraceptive methods, while an additional seven percent use less reliable traditional methods. As the use of birth control has spread, fertility has plummeted from a global average of five children per woman in 1950 to barely more than 2.5 today.
While not necessarily sufficient to depress fertility on a population-wide basis, family planning is essential to the phenomenon. Women may begin sexual activity later in life and may resort to abortion to terminate unwanted pregnancies. But humanity's average family size could not have plummeted simply because women had diplomas, contractual rights, or confidence that their children would survive. To have small families, heterosexually active women and their partners need safe and effective contraception--modern birth control.
Lessons from history suggest that women have sought and employed contraceptives since ancient times to avoid unwanted pregnancy when circumstances were inauspicious for the 15 to 18 years of parental commitment a new birth entails. Egyptian papyri that date back 4,000 years describe pessaries, ancient precursors to the diaphragm, made of acacia oil and crocodile dung. Literature from Asia to North America documents herbs used for centuries as emmenagogues, substances that induce immediate menstruation and hence expel recently fertilized eggs. In the Mediterranean, in the ages of ancient Greece and Rome, a booming trade in the contraceptive, or possibly abortifacient, silphium helped drive its source, a wild giant fennel, into extinction. And an ecclesiastical court record from 1319 preserves the personal account of a young widow in southwestern France who provided details of her use of an herbal contraception during an extended affair with a priest.
We know, too, that women and their partners historically have moderated their reproduction in response to their external environments, natural and economic. (Until modern times, these were generally the same thing.) In eighteenth- and nineteenth-century Sweden, for example, birthrates neatly tracked the price of grain crops with a roughly nine-month delay. The Japanese population during the eighteenth-century Tokugawa shogunate declined during several decades of food scarcity--until a government propaganda campaign against infanticide (the dominant method of family-size control at the time) pushed fertility well above replacement levels in the nineteenth century, restoring demographic growth.
Similar responses of fertility to external circumstances are evident today. The high cost of housing in Japan is prominent among the reasons offered by young people for delaying marriage and childbearing. In the United States, a two percent decline in the country's birthrate in 2008 was attributed largely to the deterioration of the economy.