There's a debate over when the global population will surpass the 8 billion mark. The U.S. Census Bureau, using its international database, estimated that this threshold was crossed around September 26 this year. This contrasts with the United Nations' announcement that the global population will reach 8 billion on November 15, 2022.
Different organizations have varying predictions for global population growth. The United Nations projects that the global population will peak at 10.4 billion sometime in the 2080s. In contrast, the Institute for Health Metrics and Evaluation (IHME), under the Bill and Melinda Gates Foundation, forecasts a peak of around 9.7 billion by 2064. The International Institute for Applied Systems Analysis (IIASA) in Austria predicts a peak of 9.4 billion by 2070. Both IHME and IIASA anticipate a decline to 8 billion by 2100.
Population growth predictions are crucial for national policy-making. If global population growth is slower than the UN's projections and peaks earlier, it could ease concerns about the Earth's capacity to handle climate change and food crises.
The Intergovernmental Panel on Climate Change has identified global population growth as one of the two main drivers of increased carbon dioxide emissions, the other being per capita GDP growth.
Debating the Implications of Slower Population Growth
The implications of a slowdown in population growth are debated. Some voices highlight the threats of overpopulation, while others welcome a larger population as a source of innovation.
According to the U.S. Census Bureau, differences in predictions arise from countries calculating their populations in various ways or not at all. The Bureau notes that some countries lack accurate systems to record births and deaths, and populous nations like India and Nigeria haven't conducted a census in over a decade.
Another significant factor is the varying predictions on the speed of fertility rate decline. Generally, the more developed a country is, or the faster it develops, the quicker its fertility rate falls.
Trends in Global Population Growth
The U.S. Census Bureau's latest statement, although acknowledging differing global population estimates, points out a clear trend: the pace of population growth is slowing. Population growth results from a combination of fertility rates, mortality rates, migration, and the proportion of people in specific age groups.
Developed countries like Canada are aging, with declining mortality rates among the elderly. Meanwhile, in African countries like Nigeria, the mortality rate for children under five is rapidly decreasing. At the same time, fertility rates (the average number of children per woman of childbearing age) are falling, with most of the world now below the replacement level of 2.1.
Currently, nearly three-quarters of the world's population live in countries where the fertility rate is close to or below this level, including India, Tunisia, and Argentina. About 15% live in areas with even lower fertility rates, where women have 1.6-1.8 children on average, such as Brazil, Mexico, the United States, and Sweden. Countries with extremely low fertility rates include China, South Korea, and Spain, where the rate is at or below 1.5.
Less than a quarter of the global population resides in countries with moderately high fertility rates (2.3-5.0), including Israel, Ethiopia, and Papua New Guinea. Only about 4% live in countries with very high fertility rates (above 5), all in Africa.
Future Trends and Aging Population
The U.S. Census Bureau states that global fertility rates will continue to decline until at least 2060, when "no country will have a fertility rate higher than 4." Benin is projected to have the highest fertility rate of 3.8 by 2060.
Despite declining fertility rates, the global population will continue to grow, with increased life expectancy offsetting the decline in birth rates. The growth will mainly come from the adult population. In fact, the number of newborns globally peaked in 2017, according to the U.S. Census Bureau, and future population growth will largely come from an aging population.
In the most recent population increase, a significant portion has been among the elderly. The global median age is currently 32 and rising, expected to reach 39 by 2060.
