Illustrative Projections of World Populations to the £, F 2Í St Century
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U.S. D epartment of Commerce _ FBUREAU O THE CENSUS Current Population Reports Illustrative Projections of World Populations To The £, f 2Í st Century Special БщНеБ S< Issued January 1979 \ U.S. Department of Commerce Juanita M. Kreps, Secretary Courtenay M. Slater, Chief Economist BUREAU OF THE CENSUS Manuel D. Plotkin, Director '5MB ung FBUREAU O THE CENSUS Manuel D. Plotkin, Director Robert L. Hagan, Deputy Director Daniel B. Levine, Associate Director for Demographic Fields POPULATION D IVISION Meyer Zitter, Chief ACKNOWLEDGMENTS This r eport was organized and edited in the Population Division by Maurice J. Moore and Martin O'Connell, under the general direction of Samuel Baum, Assistant Division Chief (International Demographic Statistics). Principal contributors to the content of the report are Nancy B. Frank, Larry Heligman, and Michael K. Roof. ln addition, the following staff members prepared projections for one or more individual countries: Glenda S. Finch, Roger G. Kramer, Timothy M. Markell, Sylvia D. Quick, Patrica M. Rowe, and James F. Spitler. Peggy Payne and Carol Smith posted publication tables and proofread both text and tables. Clerical and typing contributions were made by Donna M. Coppage, Claire R. Dewberry, John R. Gibson, Martha A. Greene, Kathy A. Italiano, Patrica A. Kirkpatrick, Mary S. Malachi, and Michele T. Powell, In the Publication Services Division, text and tables were edited by Paula Coupe and Helen Bonkoski, and graphics design was developed by David Coontz. Support f or this report was provided by the Development Support Bureau, Agency for international Development. Libraryf o Congress Cataloging in Publication Data United S tates. Bureau of the Census. Illustrative projections of world populations to the 21 st century. (Current p opulation reports : Special studies : Series P 23 ; no. 79) 1. Population-Statistics. 2. Vital statistics. 3. Population forecasting. l. Title. Il. Series: United States. Bureau of the Census. Current population reports : Special studies : Series P-23 ; no. 79. НА203.А218 по. 79 [HA155] 312'.0973s [312'.8] 79-947 For s ale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. Postage stamps not acceptable; currency submitted at sender's risk. Remittanœs from foreign countries must be by international money order or by a draft on a U.S. bank. Current Population Reports are sold in two subscription packages: Series P-20, P-23, P-27, and P-60 are available for $40.00 per year ($10 additional for foreign mailing); Series P-25, P-26, and P-28 are available for $70.00 per year ($17.50 additional for foreign mailing). The single-copy price of this report is $3.00. Preface The p opulation projections presented in this report were originally prepared at the request of the Council on Environmental Quality. Projections of the population of the world and of selected regions and countries to the year 2000 were required as part of an overall study to assess the probable changes in the world's population and the resulting demands that would be made on natural resources and the environment through the end of the century. The study 1 was undertaken at the direction of President Carter in his May 1977 Environmental Message. Since a ll population projections involve a considerable amount of guesswork about the course of future events, there is a very large amount of uncertainty built into the results. This is true even where current population estimates for the base projection years are reasonably good and the collection of vital statistics is well-established, as in the United States. Population projections are all the more uncertain for countries and regions where current estimates of population are doubtful and a reliable time series of vital rates is absent. This latter situation is characteristic of nations in which a majority of the world's people now live. The t hree projection series shown in this report-high, medium, and low-are provided as a way of acknowledging the uncertainty which is necessarily involved in population projections. The high and low series are not meant to define the range of possibility, but rather to set reasonable limits within which population growth (and its component elements) is expected to fall. The medium-series projection is an illustrative example of a path of population growth based on assumptions about the future course of fertility which lie between those of the high and low series. Generally, the medium-series projection is used for discussion purposes in the text of this report. The h istory of population projections is marked by the inability to foresee rapid changes in the com ponent factors, especially fertility, which determine population growth. That such factors can change rapidly is evident enough from what has happened to birth rates in the United States during the past 40 years. It is quite possible that the forces of fertility and mortality may interact over the lastl quarter of this century to produce a world population in the year 2000 that falls outside the range `marked by the high and low series projections. indeed, the fact that projections such as those contained in this report are published may serve to promote public policies and actions which will greatly affect levels of fertility and mortality in the next 20 years. Population p rojections begin with an estimate of the population size and of some measure of fertility and mortality for a "base date." The effective base date for the projections in this report is generally July 1, 1975. However, for some countries in the report, the latest available data were for a date earlier than 1975 (usually the date of the most recent census), thus making the base year earlier than 1975. То p roject a population from the base year to the year 2000, assumptions must be made about the course of fertility, mortality, and international migration. With respect to fertility rates, three paths of v/,rf/r/ the total fertility rate corresponding to the high, medium, and low projection series were projected from the base-year estimate to a target rate in the year 2000. For each projected total fertility rate, an appropri ate set of age-specific fertility rates was developed. Changes in life expectancy at birth from 1975 to 2000 were assumed to be the same in all three series, except for the People’s Republic of China (PRC) and the regions of the world which include PRC. A pattern of age-specific mortality rates was then estimated to correspond to the assumed life expectancies at birth. ‘ R esults of the study can be found in Council on Environmental Quality, Entering the 21st Century: The Report of the WTf/ President's Global 2000 Study (forthcoming). The p rocess of making projections for regions and individual countries has been simplified by the assumption that no international migration will occur after 1975. This assumption is known to be incorrect, and its effect on the projection for each country and region depends on how much net migration in that place exceeds or falls short of the assumed value of zero. The effect may be considerable, especially in countries with low levels of natural increase. ln the United States, for example, /ega/ immigration currently accounts for 20 percent or more of the annual population growth; illegal immigration is an additional element of unknown dimensions. The f act that so little is known about the number of people living in the People's Republic of China and even about the current levels of fertility and mortality in that country adds a vast element of un certainty to population estimates and projections for the world and for regions containing China. Approxi mately 1 person out of every 4 lived in China in 1975. Clearly, substantial errors in estimating and project ing the size of China’s population will have a considerable effect on the accuracy of other projections which include China. ' A m ore detailed explanation of the methods and assumptions employed in making projections for this report is provided in the introductory text and in appendix B. The introductory text also contains a sum mary c omparison of Census Bureau projections with projections prepared by other organizations. Contents Page Preface . .. .... .... .. ... .. ....... .... .. ..... ... .. .. .. ... III Regions, s ubregions, and countries .. .. .... .. .. .... .. .... .. .... ... .. .. 1 Population p rojections . ... ...... .. .. .. ... ....... ... ....... .... 2 The w orld, and more developed and less developed regions . .... .. ...... .... ...... 2 Major r egions .. .. .. .. .. ... .. .. .. .. ....... ....... .... ... ... 5 Selected c ountries .. ........ .. .... .... .. ... .... ........ 8 Population a ge structure, 1975 and 2000 .... .. ... .. ... ... .. ..... .. .. .... 9 Alternative p rojections .... .. ..... .... ... ... .. ...... .. .. ...... .. 12 Projection m ethods . .... .. .. .. ... .... ..... ... .. ... ....... .... .. ... 13 Base-year d ata . .. ... .. ..... .... .. .. ... ....... .. .. .. ..... .. 13 Assumptions a bout the future . .... .. .. .... .. ... ........ ... .. ... .. 13 Definitions a nd explanations .. ... .. ... .... .. .. .. .. ...... .. .... .. ... 15 Text T ables A. Total population, birth rate, death rate, and rate of natural increase for the world, more developed regions, and less developed regions, 1975 and 2000: High, medium, and low series. 2 B. Population growth and average annual growth rates, estimated for 1950 to 1975 and projected for 1975 to 2000: World, more developed regions, and less developed