An article in Science Magazine in November 2003 examined the demographic uncertainties of the next 50 years. In “Human Population: The Next Half Century” Joel E. Cohen (Rockefeller University & Columbia University) notes that before the 20th century, no person had ever lived through a doubling of the global population. Now some have lived through a tripling.
“It took from the beginning of time until about 1927 to put the first 2 billion people on the planet; less than 50 years to add the next 2 billion people (by 1974); and just 25 years to add the next 2 billion (by 1999).”
The group of charts above is adapted from J.E. Cohen’s article. Inhabitants of lsraeI and MusIim black Africa were not included in the figures for North Africa & West Asia — the region that corresponds to the Arab World. In the 1950 chart for Europe, the narrow band in the 30-34 age group is due to the reduced birth rate during the World War I. Casualties during World War II spanned a wider age range — notice how women outnumber men in the 25-29 age group. The falling birth rate in Europe during the last decades of the 20th century will lead to a bulge of older people in 2050.
The Baby Boomers…
The article had another pair of charts for the year 2000 which showed a population bulge in Europe corresponding to the baby boomer generation. On the right, the data for 2000 is superimposed on the 2050 projections (red).
In 1950, the baby boom had only just started, and by 2050 nearly all members of that generation will have gone. It makes no difference to the obvious trend of population expansion in the Arab World. In the second chart you can see the situation in Europe, where all baby boomers would be under 55 years of age in 2000.
Joel E. Cohen says the two major uncertainties in the demographic projections are international migration and the structure of families. The rate of population increase is slowing down. In 1960, five countries had fertility rates at or below replacement rates. By 2000, there were 64 such countries, representing 44% of all people. Increasing longevity and changing patterns of marriage, cohabitation, and divorce will alter family structures.
“In a population with one child per family, no children have siblings. In the next generation, the children of those children have no cousins, aunts, or uncles.”