ABSTRACT
Global population grew very rapidly during the second half of the twentieth century. Although population growth rates are now slowing, total annual additions to global population are still close to all-time highs, with a global population of 7.9 billion in 2021. Growth is projected to continue for at least the next three decades, reaching a level of 9–10 billion by 2050, with some longer-term projections of 11 billion or more by 2100. More than 90% of the projected growth will be in the developing countries of Asia, Africa, and Latin America.
Population projections offer no certainty about actual future numbers, but the population momentum phenomenon guarantees significant further growth. Currently, average fertility rates (number of children per woman) are still high throughout the developing world. Although fertility rates are generally falling, it will be decades before the population stabilizes. Some projections based on more rapid fertility decline see global population stabilizing at about 8.5 billion by 2050, and declining thereafter.
In Europe, the demographic transition from rapid population growth to relatively stable population has already been achieved. In the United States, growth continues due to both population momentum and annual immigration. In the developing world, the demographic transition is far from finished, and significant uncertainty remains about future birth rates. Economic growth, social equity, access to contraception, and cultural factors all play a role.
The economic analysis of population growth emphasizes the potential of other factors, such as technological progress, to offset the effects of population growth. Under favorable conditions for economic and technological progress, population growth may be accompanied by rising living standards. However, rapid population growth accompanied by social inequity and significant environmental externalities may lead to a decline in living standards.
An ecological perspective recognizes more stringent limits to the population carrying capacity of regional and global ecosystems. Greater population increases the demand for materials, energy, and natural resources, which in turn increases pressures on the environment. Given the extent of existing environmental damage, especially where this damage is cumulative or irreversible, the challenge of providing for significantly larger populations poses severe challenges to the earth’s ecosystems.
Compulsory population control policies generally fail to alter basic incentives regarding fertility. More effective population policy measures include improved nutrition and health care, greater social equity, women’s education, and availability of contraception.
