The Lancet has just published a recent set of papers from the Global Burden of Disease Study. As it notes: "The Global Burden of Disease Study (GBD) is the most comprehensive worldwide observational epidemiological study to date. It describes mortality and morbidity from major diseases, injuries and risk factors to health at global, national and regional levels. Examining trends from 1990 to the present and making comparisons across populations enables understanding of the changing health challenges facing people across the world in the 21st century."
Interested readers will find lots to chew on in these papers. Here, I'll stick to a figure showing "global population pyramids" from the article "Population and fertility by age and sex for 195 countries andterritories, 1950–2017: a systematic analysis for the Global Burden of Disease Study 2017," authored by the GBD 2017 Population and Fertility Collaborators (Lancet, published November 10, 2018; 392: 10159, pp. 1995–2051).
The four panels show four years: 1950, 1975, 2000, and 2017. The red bars show size of female population at different age groups, from younger ages at the bottom to older ages at the top; the yellow bars do the same for men. Horizontal lines show the average and median age for men and women in each year.
A few thoughts:
1) These population pyramids are especially useful for looking at the evolution of the age distribution. "In 1950, the global mean age of a person was 27 years, decreasing to 26 years in 1975, then increasing to 29 years in 2000 and 32 years in 2017.
2) The bulge in the working age population in 2000 and 2017, as opposed to the earlier years, is apparent. " Demographic change has economic consequences, and the proportion of the population that is of working age (15–64 years) decreased from 60% in 1950 to 57% in 1975, then increased to 63% in 2000 and 65% in 2017."
3) Over time, the population pyramids has become relatively broader at the bottom; that is, they do not taper as quickly as one moves to older aged. That pattern tells you that the elderly are a rising share of the population. It also suggests that as today's younger generations age, and their number rise up through the global population pyramid, the share of the elderly in the world population will rise substantially.
4) The increasing area of the pyramids shows the rise in global population since 1950. Less clear to the naked eye is that the rate of growth in the world population has shifted from being exponential to being linear.
"From 1950 to 1980, the global population increased exponentially at an annualised rate of 1.9% ... . From 1981 to 2017, however, the pace of the global population increase has been largely linear, increasing by 83.6 million people per year. ... Growth of the global population increased in the 1950s and reached 2.0% per year in 1964, then slowly decreased to 1.1% in 2017."
5) Although geographic breakdowns aren't shown in this figure, the regional patterns of population growth have also differed substantially.
"In 1950, the high-income, central Europe, eastern Europe, and central Asia GBD super-regions accounted for 35.2% of the global population but, in 2017, the populations of these countries accounted for 19.5% of the global population. Large increases occurred in the proportion of the world’s population living in south Asia, sub-Saharan Africa, Latin America and the Caribbean, and north Africa and the Middle East. ... Growth of the population in north Africa and the Middle East increased until the 1970s, and it has remained quite high, at 1.7% in 2017. Population growth rates in sub-Saharan Africa increased from 1950 to 1985, decreased during 1985–1993, increased again until 1997, and then plateaued; at 2.7% in 2017, population growth rates were almost the highest rates ever recorded in this region. The most substantial changes to population growth rates were in the southeast Asia, east Asia, and Oceania super-region, where the population growth rate decreased from 2.5% in 1963 to 0.7% in 2017. ... In central Europe, eastern Europe, and central Asia, the population growth rate dropped rapidly after 1987 and was negative from 1993 to 2008. Growth rates in the high-income super-region have changed the least, starting at 1.2% in 1950 and reaching 0.4% in 2017."
A version of this article first appeared on Conversable Economist.
Timothy Taylor is an American economist. He is managing editor of the Journal of Economic Perspectives, a quarterly academic journal produced at Macalester College and published by the American Economic Association. Taylor received his Bachelor of Arts degree from Haverford College and a master's degree in economics from Stanford University. At Stanford, he was winner of the award for excellent teaching in a large class (more than 30 students) given by the Associated Students of Stanford University. At Minnesota, he was named a Distinguished Lecturer by the Department of Economics and voted Teacher of the Year by the master's degree students at the Hubert H. Humphrey Institute of Public Affairs. Taylor has been a guest speaker for groups of teachers of high school economics, visiting diplomats from eastern Europe, talk-radio shows, and community groups. From 1989 to 1997, Professor Taylor wrote an economics opinion column for the San Jose Mercury-News. He has published multiple lectures on economics through The Teaching Company. With Rudolph Penner and Isabel Sawhill, he is co-author of Updating America's Social Contract (2000), whose first chapter provided an early radical centrist perspective, "An Agenda for the Radical Middle". Taylor is also the author of The Instant Economist: Everything You Need to Know About How the Economy Works, published by the Penguin Group in 2012. The fourth edition of Taylor's Principles of Economics textbook was published by Textbook Media in 2017.