Population, Sustainability, and Earth's Carrying Capacity:
While there has been a steady increase of population growth during the past two or three centuries, it has been especially rapid during the past 20 years.
To appreciate the pace of population growth we should recall that world population doubled in about 1, years from the time of Christ until the middle of the 17th century; it doubled again in about years, doubled again in less thanand, if the current rate of population increase were to remain constant, would double every 35 years.
Moreover, this rate is still increasing. To be sure, the rate of increase cannot continue to grow much further. Even if the death rate were to fall to zero, at the present level of human reproduction the growth rate would not be much in excess of three and one-half per cent per year, and the time required for world population to double would not fall much below 20 years.
Although the current two per cent a year does not sound like an extraordinary rate of increase, a few simple calculations demonstrate that such a rate of increase in human population could not possibly continue for more than a few hundred years. The Growth of World Population: Analysis of the Problems and Recommendations for Research and Training.
The National Academies Press. If the present world population should continue to increase at its present rate of two per cent per year, then, within two centuries, there will be more than billion people. Calculations of this sort demonstrate without question not only that the current continued increase in the rate of population growth must cease but also that this rate must decline again.
There can be no doubt concerning this long-term prognosis: Either the birth rate of the world must come down or the death rate must go back up. Among the industrialized countries, Japan and most of the countries of Europe are now growing relatively slowly—doubling their populations in 50 to years.
Another group of industrialized countries—the United States, the Soviet Union, Australia, New Zealand, Canada, and Argentina—are doubling their populations in 30 to 40 years, approximately the world average. Annual growth rates in all these areas range from one and one-half to three and one-half per cent, doubling in 20 to 40 years.
The rates of population growth of the various countries of the world are, with few exceptions, simply the differences between their birth rates and death rates. International migration is a negligible factor in rates of growth today.
Thus, one can understand the varying rates of population growth of different parts of the world by understanding what underlies their respective birth and death rates. Page 10 Share Cite Suggested Citation: A simplified picture of the population history of a typical western European country is shown in Figure 1.
Schematic presentation of birth and death rates in western Europe after The time span varies roughly from 75 to years. Page 11 Share Cite Suggested Citation: The jagged interval in the early death rate and the recent birth rate is intended to indicate that all the rates are subject to substantial annual variation.
The birth rate in was about 35 per 1, population and the average number of children ever born to women reaching age 45 was about five.
The death rate in averaged 25 to 30 per 1, population although, as indicated, it was subject to variation because of episodic plagues, epidemics, and crop failures.
The average expectation of life at birth was 35 years or less. The current birth rate in western European countries is 14 to 20 per 1, population with an average of two to three children born to a woman by the end of childbearing.
The death rate is 7 to 11 per 1, population per year, and the expectation of life at birth is about 70 years. The death rate declined, starting in the late 18th or early 19th century, partly because of better transport and communication, wider markets, and greater productivity, but more directly because of the development of sanitation and, later, modern medicine.
These developments, part of the changes in the whole complex of modern civilization, involved scientific and technological advances in many areas, specifically in public health, medicine, agriculture, and industry. The immediate cause of the decline in the birth rate was the increased deliberate control of fertility within marriage.
The only important exception to this statement relates to Ireland, where the decline in the birth rate was brought about by an increase of several years in the age at marriage combined with an increase of 10 to 15 per cent in the proportion of people remaining single.
The average age at marriage rose to 28 and more than a fourth of Irish women remained unmarried at age In other countries, however, such social changes have had either insignificant or favorable effects on the birth rate. In these countries—England, Wales, Scotland, Scandinavia, the Low Countries, Germany, Switzerland, Austria, and France—the birth rate went down because of the practice of contraception among married couples.
It is certain that there was no decline in the reproductive capacity; in fact, with improved health, the contrary is likely. Only a minor fraction of the decline in western European fertility can be ascribed to the invention of modern techniques of contraception.
In the first place, very substantial declines in some European countries antedated the invention and mass manufacture of contraceptive devices. There is similar direct evidence for other European countries.Using the latest Census Bureau data from and , this paper provides a detailed picture of the more than 50 million immigrants (legal and illegal) and their U.S.-born children (under 18) in the United States by country of birth, state, and legal status.
With member countries, staff from more than countries, and offices in over locations, the World Bank Group is a unique global partnership: five institutions working for sustainable solutions that reduce poverty and build shared prosperity in developing countries.
The following plot is a rough estimate of world population from the time of the Flood of Noah, until the birth of Jesus, (53 generations). For discussion purposes the population at the time of Abraham, eleven generations after the Flood, has been taken to be one million people.
The U.S. population grew from million in to million in , a 78% increase. We will have doubled in 57 years. Population in the world is currently () growing at a rate of around % per year (down from % in and % in ). The current average population increase is estimated at 83 million people per year..
Annual growth rate reached its peak in the late s, when it was at around 2%. Fertility rates have fallen in most Muslim-majority countries in recent decades. Yet they remain, on average, higher than in the rest of the developing world and considerably higher than in more-developed countries.
This is one of the main reasons that the global Muslim population is projected to.