The questions remain: how fast, how much, and where? The declines in birth rates and increased longevity has led to a concern in more developed countries and one that will soon spread to less developed countries: The proportion of the elderly population has been rising and will continue. The pressure on national pension plans and long-term health care has increased as the support ratio, the number of those ages 15 to 64 compared with those ages 65 and over, decreases.The population size of the world's more developed countries has essentially peaked.

What little growth remains will mostly come from immigration from less developed countries. A number of more developed countries are likely to decline in size and see the proportion of their elderly populations rise to unprecedented levels. The outlook for less developed countries is quite different. The increase in world population from 1.6 billion in 1900 to 6.1 billion in 2000 was almost entirely due to population growth in those countries. The 20th-century population "explosion" was a direct result of the rapid decline in mortality rates in less developed countries. Achievements in rising life expectancy that had taken centuries in Europe took mere decades in many less developed countries. As less developed countries' growth rates rose to levels never experienced in the more developed countries, many adopted policies to lower the birth rate to keep pace with rapidly declining death rates. In the decades that followed, there were dramatic declines in birth rates in some less developed countries, somewhat more gradual declines in others, and almost no decline in still others. Nonetheless, the total fertility rate (TFR) in less developed countries declined from about 6.0 in the early 1950s to about 2.5 today, a much more rapid decrease than that of Europe and North America. As impressive as that decline may be, there is still a long way to go. Global population is at an important crossroad. Will the world continue on to "zero population growth" or not?

> Download the report