Sharply lower birth rates coupled with breakthroughs in medical science are leading to a dramatic rise in the proportion of the global population over age 65, says Peter G. Peterson, chairman of the Council on Foreign Relations.

In a current Foreign Affairs article, Peterson calls this the "gray dawn," and says it will have several predictable consequences for national economies, especially in affluent industrialized countries: worker shortages, immigration pressures and governments facing a choice between bankruptcy and radical reforms of national pension schemes.

Before the Industrial Revolution in the 19th century, people over 65 never comprised more than two to three percent of the population.

• Today, they make up 14 percent of the population in the developed world.

• In the U.S. during 1998, those over 65 amounted to 12.7 percent of all Americans -- a proportion which is predicted to grow to 16.5 percent by 2020.

• The over-65 group in Germany now comprises 15.9 percent of the population -- with the figure predicted to rise to 23.2 percent by 2020.

• In Japan, 16 percent are now over 65 and 26.3 percent will be in 2020.

Sources: Peter G. Peterson, "Gray Dawn: The Global Aging Crisis, " Foreign Affairs, January/February 1999; Jon Omicinski, "Aging Population Gives All Gray Hairs," USA Today, January 7, 1999.