1. Origins of the Population Explosion

1) Is the population explosion an illusion?

The Industrial Revolution (from the 1770s to the 1830s), which began in England, promoted modernization in countries in the West. Demographically, it was a time when population growth rates in these countries became stabilized. The world population around early A.D. is estimated to have been around 300 million, and 1,800 years later it reached 1 billion.

Thomas Robert Malthus published his famous book, "An Essay on the Principle of Population as it Affects the Future Improvement of Society, with Remarks on the Speculations of Mr. Godwin, M. Condorcet, and Other Writers (London, Johnson, 1798). Based on detailed historical studies, he calculated average growth rates of population and food production, and predicted the fate of human beings caused by an unavoidable gap between the geometric growth of population and the arithmetic growth of food production.
The world population at Malthus' time of 1 billion increased to 1.6 billion 100 years later in 1900, 2.5 billion in 1950, and 6 billion in 2000. The growth rates rose sharply during the past two centuries from 0.5 percent (1800-1900), 0.8 percent (1900-1950) to around 2 percent (1950-2000).

2) Theories of Population Explosion and Statistics

The theoretical ground for the explosive increase in world population was "Limits to Growth," a research study by Prof. Donella H. Meadows and his group, conducted at the request of the Club of Rome and published in 1972. This book was translated into many languages and exerted a strong impact on the world. As it proposed even zero economic growth, some experts expressed their distrust of the views presented in the book.

Research studies on the capacity of the earth to support human beings by international agencies and research institutes published at the same time revealed that this capacity was approaching its limits.

The United Nations Population Division revises its population projection every two years. The latest one, the 19th projection, was published in 2004. The detailed population-related statistics by region and country provide basic data for future world population analyses. In addition to the UN Population Division, the US Statistics Bureau and the International Institute for Applied Statistical Analysis (IIASA) in Austria are publishing their population projections. A notable point is that the projections of all these agencies are similar. They suggest that a future change of course in world population will come about from different sources.

3) Population Equilibrium and Population Explosion

A population explosion occurs when the population balance is upset for some reason. Vital statistics are usually stable but may change because of changes in social, economic, political or natural factors. These changes usually are brought to a close rapidly, and population dynamic phenomena such as births and deaths move to restore equilibrium.

World War II brought an enormous number of deaths, including civilians, amounting to nearly 60 million. Births declined during the war, and in some years, natural growth rates were negative. Remarkable declines in population in the countries involved in WWII brought about phenomena for social and biological restoration of the population balance. Thus, postwar baby booms occurred in many countries that participated in the war. Japan was not an exception. At its peak in 1947, the total fertility rate was recorded at 4.5 persons and birth rate a little over 34 per 1,000 people. This birth rate went back to its prewar average quickly.

Phenomena in recovering the population balance are different between industrialized and developing countries. The pattern in the former shows a rapid rising pattern with a remarkable natural increase caused by postwar baby booms on the base of the low fertility standards that had been established before the war. In contrast, in developing countries, rapid improvement in mortality (as the consequence of development aid by the UN and industrialized countries) on the base of high birth rates contributed to the rapid world population increase. It is this fall in death rates that triggered the population explosion.

(Fig. 1) (CBR: crude birth rate CDR: crude death rate NIR: natural increase rate)

4) Challenges for the first half of the 21st century

The greatest challenge for the first half of this century will be the construction of a peaceful aged society. The key to this lies in the creation of new population transition theories.

The 21st century will mark a great turning period when the long historic development process of humans will be reversed. The scale and content of the reversing phenomenon will be determined by the scale of change in vital statistics that have constituted the existing economic, social and political systems. Rapid and diversitied changes in vital statistics and consequential demographic structural changes in the world population may be a great for the peaceful sustainability of human beings with a stable world population over time. In other words, the remaining years of the earlier half of the century will be a critically important time for the theoretical and realistic quest of an open and new population revolution.