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Almost all growth will take place in the less developed regions, where today's 5.3 billion population of underdeveloped countries is expected to increase to 7.8 billion in 2050. By contrast, the population of the more developed regions will remain mostly unchanged, at 1.2 billion. An exception is the United States population, which is expected to increase 31% from 305 million in 2008 to 400 million in 2050 due to projected net international migration.<ref>http://www.census.gov/population/projections/data/national/2012.html]</ref> In 2000–2005, the average world fertility was 2.65 children per woman, about half the level in 1950–1955 (5 children per woman). In the medium variant, global fertility is projected to decline further to 2.05 children per woman.
Almost all growth will take place in the less developed regions, where today's 5.3 billion population of underdeveloped countries is expected to increase to 7.8 billion in 2050. By contrast, the population of the more developed regions will remain mostly unchanged, at 1.2 billion. An exception is the United States population, which is expected to increase 31% from 305 million in 2008 to 400 million in 2050 due to projected net international migration.<ref>http://www.census.gov/population/projections/data/national/2012.html]</ref> In 2000–2005, the average world fertility was 2.65 children per woman, about half the level in 1950–1955 (5 children per woman). In the medium variant, global fertility is projected to decline further to 2.05 children per woman.

Predictions depend on assumptions, such as whether [[ebola]] will become endemic.<ref>{{cite journal|author1=Debora MacKenzie|title=World wakes up to Ebola as cases set to top 1 million|journal=[[New Scientist]]|date=27 Sept., 2014|pages=8-9|url=http://www.newscientist.com/article/dn26258-world-wakes-up-to-ebola-as-cases-set-to-top-1-million.html?full=true}}</ref>


== Growth regions ==
== Growth regions ==
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==After 2050==
Projections for after 2050 have usually assumed that fertility rates will have declined by then and the population will be stable or will decrease. However, a study in 2014 found that fertility rates in Africa have leveled off at around 4.6 instead of continuing to decline, and that consequently world population may be as high as 12 300 million by 2100. Reasons for the continuing high fertility rate include better survival rates with respect to HIV, and lack of availability of contraception.<ref name=NS>{{cite journal|author1=Andy Coghlan|title=Global population may boom well beyond the year 2050|journal=New Scientist|date=27 Sept., 2014|page=11|url=http://www.newscientist.com/article/mg22329882.800-global-population-may-boom-well-beyond-the-year-2050.html}}</ref><ref>{{cite journal|author1=Patrick Gerland, Adrian Raftery ''et al.''|title=World population stabilization unlikely this century|journal=Science|date=18 Sept., 2014|doi=10.1126/science.1257469}}</ref> Another study on the other hand concludes that education of women will lead to low fertility rates even in Africa.<ref name=NS/>


==See also==
==See also==

Revision as of 14:55, 25 September 2014

Projected world population growth.

According to current projections of population growth, the world population of humans will continue to grow until at least 2050, with the estimated population, based on current growth trends, to reach 9 billion in 2040,[1][2] and some predictions putting the population in 2050 as high as 11 billion.[3] World population passed the 7 billion mark on October 31, 2011.[1]

According to the United Nations' World Population Prospects report,[4] the world population is currently growing by approximately 74 million people per year. Current United Nations predictions estimate that the world population will reach 9.0 billion around 2050, assuming a decrease in average fertility rate from 2.5 down to 2.0.[5][6]

Almost all growth will take place in the less developed regions, where today's 5.3 billion population of underdeveloped countries is expected to increase to 7.8 billion in 2050. By contrast, the population of the more developed regions will remain mostly unchanged, at 1.2 billion. An exception is the United States population, which is expected to increase 31% from 305 million in 2008 to 400 million in 2050 due to projected net international migration.[7] In 2000–2005, the average world fertility was 2.65 children per woman, about half the level in 1950–1955 (5 children per woman). In the medium variant, global fertility is projected to decline further to 2.05 children per woman.

Predictions depend on assumptions, such as whether ebola will become endemic.[8]

Growth regions

A world map showing global variations in fertility rate per woman, according to the CIA World Factbook's 2013 data.

During 2005–2050, nine countries are expected to account for half of the world's projected population increase: India, Pakistan, Nigeria, Democratic Republic of the Congo, Bangladesh, Uganda, United States, Ethiopia, and China, listed according to the size of their contribution to population growth. China would be higher still in this list were it not for its One Child Policy.

Global life expectancy at birth, which is estimated to have risen from 46 years in 1950–1955 to 65 years in 2000–2005, is expected to keep rising to reach 75 years in 2045–2050. In the more developed regions, the projected increase is from 75 years today to 82 years by mid-century. Among the least developed countries, where life expectancy today is just under 50 years, it is expected to be 66 years in 2045–2050. The population of 51 countries or areas, including Germany, Italy, Japan and most of the successor States of the former Soviet Union, is expected to be lower in 2050 than in 2005.

Projected migration to Western countries

According to the United Nations, during 2005–2050 the net number of international migrants to more developed regions is projected to be 98 million. Because deaths are projected to exceed births in the more developed regions by 73 million during 2005–2050, population growth in those regions will largely be due to international migration. In 2000–2005, net migration in 28 countries either prevented population decline or doubled at least the contribution of natural increase (births minus deaths) to population growth. These countries include Austria, Canada, Croatia, Denmark, Germany, Italy, Portugal, Qatar, Singapore, Spain, Sweden, United Arab Emirates and United Kingdom.[9] Birth rates are now falling in a small percentage of developing countries, while the actual populations in many developed countries would fall without immigration.[5]

By 2050 (Medium variant), India will have 1.6 billion people, China 1.4 billion, United States 439 million, Pakistan 309 million, Indonesia 280 million, Nigeria 259 million, Bangladesh 258 million, Brazil 245 million, Democratic Republic of the Congo 189 million, Ethiopia 185 million, Philippines 141 million, Mexico 132 million, Egypt 125 million, Vietnam 120 million, Russia 109 million, Japan 103 million, Iran 100 million, Turkey 99 million, Uganda 93 million, Tanzania 85 million, Kenya 85 million, Germany 83 million and United Kingdom 80 million.

World population in 2050

Estimates of population levels in different continents between 1950 and 2050, according to the United Nations. The vertical axis is logarithmic and is in millions of people.

Walter Greiling projected in the 1950s that world population would reach a peak of about nine billion, in the 21st century, and then stop growing after a readjustment of the Third World and a sanitation of the tropics.[11] Recent extrapolations from available figures for population growth show that the population of Earth will stop increasing around 2070.[12]

The United Nations Department of Economic and Social Affairs report (2004) projects the world population to peak at 9.22 billion in 2075. After reaching this maximum the world population is projected to decline slightly and then resume increasing slowly, to reach a level of 8.97 billion by 2300, about the same as the projected 2050 figure.[13] A 2014 paper by demographers from several universities and the United Nations Population Division forecast that the world's population will reach about 10.9 billion in 2100 and continue growing thereafter.[14] An alternative scenario is given by Jorgen Randers, who argues that traditional projections insufficiently take into account the downward impact of global urbanization on fertility. Randers' "most likely scenario" reveals a peak in the world population in the early 2040s at about 8.1 billion people, followed by decline.[15]

These projected growth patterns depend on assumptions about vital rates. Total fertility is assumed to continue to decline, at varying paces depending on circumstances in individual countries, to a below-replacement level of 1.85 children per woman by mid century. Countries already at this level or below, and other countries when they reach it, will eventually return to replacement over a period of a century and stay at replacement going forward. All countries are projected to have reached replacement fertility by 2175.

Some of the authors of the report say that life expectancy is assumed to rise slowly and continuously. The projections in the report assume this with no upper limit, though at a slowing pace depending on circumstances in individual countries. By 2100, the report assumes life expectancy to be from 66 to 97 years, and by 2300 from 87 to 106 years, depending on the counrty. Based on that assumption, they said that rising life expectancy will produce small but continuing population growth by the end of the projections, ranging from 0.03 to 0.07 percent annually.

However, based on recent research, many expect that life expectancy will leap ahead and indefinite human lifespans are not necessarily unfeasible.[16][17][18] This could significantly raise the estimates. In an essay within the U.N. report, Tim Dyson said,

"A rapid increase in life expectancy, which would raise the population pyramids, seems within reach, since it responds to an old and powerful demand for longevity."[19]

Most populous nations by 2050

The United Nations Population Fund has calculated, based on current trends, the future population of the world's countries. These figures can easily change as events such as wars, diseases, breakthroughs in life extension technologies, or dramatic demographic changes would all greatly affect the results. The study projected the world population in 2030 to be 8.321 billion.[20]

Projected
Rank
2050		 Current
Rank
2014		 Change Country Projected
Population (2030)		 Population (2010) Population
change
(per cent)
— — —  World 8,321,380,000 6,895,889,000 +20.7%
01 02 +1  India (demographics) 1,523,482,000 1,224,614,000 +24.4%
02 01 −1  China (demographics) 1,393,076,000 1,341,335,000 +3.9%
03 03 =  United States (demographics) 361,680,000 310,384,000 +16.5%
04 04 =  Indonesia (demographics) 279,659,000 239,871,000 +16.6%
05 07 +2  Nigeria (demographics) 257,815,000 158,423,000 +62.7%
06 06 =  Pakistan (demographics) 234,432,000 173,593,000 +35.0%
07 05 −2  Brazil (demographics) 220,492,000 194,946,000 +13.1%
08 08 =  Bangladesh (demographics) 181,863,000 148,692,000 +22.3%
09 09 =  Russia (demographics) 136,429,000 142,958,000 −4.6%
10 11 +1  Mexico (demographics) 135,398,000 113,423,011 +19.4%

After 2050

Projections for after 2050 have usually assumed that fertility rates will have declined by then and the population will be stable or will decrease. However, a study in 2014 found that fertility rates in Africa have leveled off at around 4.6 instead of continuing to decline, and that consequently world population may be as high as 12 300 million by 2100. Reasons for the continuing high fertility rate include better survival rates with respect to HIV, and lack of availability of contraception.[21][22] Another study on the other hand concludes that education of women will lead to low fertility rates even in Africa.[21]

See also

References

  1. ^ a b "World Population Clock". Worldometers. Retrieved 24 October 2011.
  2. ^ International Data Base (IDB) — World Population
  3. ^ http://esa.un.org/unpp/
  4. ^ World Population Prospects
  5. ^ a b United Nations Population Division Home Page, United Nations Department of Economic and Social Affairs
  6. ^ Microsoft Word – WorldPOP2300.doc
  7. ^ http://www.census.gov/population/projections/data/national/2012.html]
  8. ^ Debora MacKenzie (27 Sept., 2014). "World wakes up to Ebola as cases set to top 1 million". New Scientist: 8–9. {{cite journal}}: Check date values in: |date= (help)
  9. ^ http://www.un.org/News/Press/docs/2005/pop918.doc.html [dead link]
  10. ^ United Nations, Department of Economic and Social Affairs, Population Division (2013). "World Population Prospects: The 2012 Revision. File POP/1-1: Total population (both sexes combined) by major area, region and country, annually for 1950-2100 (thousands). Medium fertility, 2010-2100" (XLS). esa.un.org. United Nations. Retrieved 29 November 2013.{{cite web}}: CS1 maint: multiple names: authors list (link)
  11. ^ Walter Greiling: Wie werden wir leben? ("How are we going to live?") Econ publishers, Munich 1954
  12. ^ Ciro Pabón y Ciro Pabón, Manual de Urbanismo, Editorial Leyer, Bogotá, 2007, ISBN 978-958-711-296-2
  13. ^ United Nations Department of Economic and Social Affairs. World Population to 2300. 2004. Executive Summary, Page 2.
  14. ^ Template:Cite doi/10.1126.2Fscience.1257469
  15. ^ Randers, Jorgen (2012). 2052: A Global Forecast for the Next Forty Years. Vermont: Chelsea Green Publishing. p. 62.
  16. ^ Newmark PA, Sánchez Alvarado A (2002). Not your father's planarian: a classic model enters the era of functional genomics. Nat Rev Genet 3:210-219. PMID 11972158
  17. ^ Bavestrello, Giorgio; Christian Sommer and Michele Sarà (1992). Bi-directional conversion in Turritopsis nutricula (Hydrozoa). Scientia Marina 56 (2–3): 137–140
  18. ^ Martínez DE (1998). Mortality patterns suggest lack of senescence in hydra. Exp Gerontol 33(3):217-225. PMID 9615920
  19. ^ Cite error: The named reference un-esal was invoked but never defined (see the help page).
  20. ^ World Population Prospects, the 2010 Revision[dead link]
  21. ^ a b Andy Coghlan (27 Sept., 2014). "Global population may boom well beyond the year 2050". New Scientist: 11. {{cite journal}}: Check date values in: |date= (help)
  22. ^ Patrick Gerland, Adrian Raftery; et al. (18 Sept., 2014). "World population stabilization unlikely this century". Science. doi:10.1126/science.1257469. {{cite journal}}: Check date values in: |date= (help); Explicit use of et al. in: |author1= (help)
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