World population


Population density (people per km²) by country, 2006
Population by region as a percentage of world population (1750–2005)

The term world population commonly refers to the total number of living humans on Earth at a given time. As of 5 July 2009 (UTC), the Earth's population is estimated by the United States Census Bureau to be 6.769 billion.[1] The world population has been growing continuously since the end of the Black Death around 1400.[2] There were also short term falls at other times due to plague, for example in the mid 17th century.[citation needed] The fastest rates of world population growth (above 1.8%) were seen briefly during the 1950s then for a longer period during the 1960s and 1970s (see graph). According to population projections, world population will continue to grow until around 2050. The 2008 rate of growth has almost halved since its peak of 2.2% per year, which was reached in 1963. World births have levelled off at about 134-million-per-year, since their peak at 163-million in the late 1990s, and are expected to remain constant. However, deaths are only around 57 million per year, and are expected to increase to 90 million by the year 2050. Since births outnumber deaths, the world's population is expected to reach about 9 billion by the year 2040.[3][4]

Contents

Population figures

A dramatic population bottleneck is theorized for the period around 70,000 BCE (see Toba catastrophe theory). After this time and until the development of agriculture, it is estimated that the world population stabilized at about one million people whose subsistence entailed hunting and foraging, a lifestyle that by its nature ensured a low population density. It is estimated that over 55 million people lived in the combined eastern and western Roman Empire (300–400 AD).[5] The Plague of Justinian caused Europe's population to drop by around 50% between 541 and the 700s.[6] The Black Death pandemic in the 14th century may have reduced the world's population from an estimated 450 million to between 350 and 375 million in 1400.[7]

At the founding of the Ming dynasty in 1368, China's population was reported to be close to 60 million, and toward the end of the dynasty in 1644 it might have approached 150 million.[8] New crops that had come to Asia from the Americas via the Spanish colonizers in the 16th century contributed to the population growth.[9] Encounters between European explorers and populations in the rest of the world often introduced local epidemics of extraordinary virulence. Archaeological evidence indicates that the death of 90 to 95% of the Native American population of the New World was caused by Old World diseases such as smallpox, measles, and influenza.[10] Over the centuries, the Europeans had developed high degrees of immunity to these diseases, while the indigenous peoples had no such immunity.[11]

During the Agricultural and Industrial Revolutions, the life expectancy of children increased dramatically.[12] The percentage of the children born in London who died before the age of five decreased from 74.5% in 1730-1749 to 31.8% in 1810-1829.[13] Europe’s population doubled during the 18th century, from roughly 100 million to almost 200 million, and doubled again during the 19th century.[14] The population of the Indian subcontinent, which stood at about 125 million in 1750, had reached 389 million by 1941.[15]

Below is a table with historical and predicted population figures shown in millions.[16][17][18][19]
The availability of historical population figures varies by region.

World historical and predicted populations (in millions)[20]
Region 1750 1800 1850 1900 1950 1999 2008 2050 2150
World 791 978 1,262 1,650 2,521 5,978 6,707 8,909 9,746
Africa 106 107 111 133 221 767 973 1,766 2,308
Asia 502 635 809 947 1,402 3,634 4,054 5,268 5,561
Europe 163 203 276 408 547 729 732 628 517
Latin America and the Caribbean * 16 24 38 74 167 511 577 809 912
Northern America * 2 7 26 82 172 307 337 392 398
Oceania 2 2 2 6 13 30 34 46 51
World historical and predicted populations by percentage distribution
Region 1750 1800 1850 1900 1950 1999 2008 2050 2150
World 100 100 100 100 100 100 100 100 100
Africa 13.4 10.9 8.8 8.1 8.8 12.8 14.5 19.8 23.7
Asia 63.5 64.9 64.1 57.4 55.6 60.8 60.4 59.1 57.1
Europe 20.6 20.8 21.9 24.7 21.7 12.2 10.9 7.0 5.3
Latin America and the Caribbean * 2.0 2.5 3.0 4.5 6.6 8.5 8.6 9.1 9.4
Northern America * 0.3 0.7 2.1 5.0 6.8 5.1 5.0 4.4 4.1
Oceania 0.3 0.2 0.2 0.4 0.5 0.5 0.5 0.5 0.5
Estimated world population at various dates (in thousands)
Year World Africa Asia Europe Latin America * Northern America* Oceania Notes
70,000 BCE < 1,000 [21]
10,000 BCE 1,000
9000 BCE 3,000
8000 BCE 5,000 [22]
7000 BCE 7,000
6000 BCE 10,000
5000 BCE 15,000
4000 BCE 20,000
3000 BCE 25,000
2000 BCE 35,000
1000 BCE 50,000 [22]
500 BCE 100,000 [22]
1 200,000 [23]
1000 310,000
1750 791,000 106,000 502,000 163,000 16,000 2,000 2,000
1800 978,000 107,000 635,000 203,000 24,000 7,000 2,000
1850 1,262,000 111,000 809,000 276,000 38,000 26,000 2,000
1900 1,650,000 133,000 947,000 408,000 74,000 82,000 6,000
1950 2,518,629 221,214 1,398,488 547,403 167,097 171,616 12,812
1955 2,755,823 246,746 1,541,947 575,184 190,797 186,884 14,265
1960 2,981,659 277,398 1,674,336 601,401 209,303 204,152 15,888
1965 3,334,874 313,744 1,899,424 634,026 250,452 219,570 17,657
1970 3,692,492 357,283 2,143,118 655,855 284,856 231,937 19,443
1975 4,068,109 408,160 2,397,512 675,542 321,906 243,425 21,564
1980 4,434,682 469,618 2,632,335 692,431 361,401 256,068 22,828
1985 4,830,979 541,814 2,887,552 706,009 401,469 269,456 24,678
1990 5,263,593 622,443 3,167,807 721,582 441,525 283,549 26,687
1995 5,674,380 707,462 3,430,052 727,405 481,099 299,438 28,924
2000 6,070,581 795,671 3,679,737 727,986 520,229 315,915 31,043
2005 6,453,628 887,964 3,917,508 724,722 558,281 332,156 32,998
Jul. 1, 2008 6,706,993 972,752 4,053,868 731,683 577,147 337,168 34,375 [1]
Year World Africa Asia Europe Latin America* Northern America* Oceania Notes

* Northern America comprises the northern countries and territories of North America: Canada, the United States, Greenland, Bermuda, and St. Pierre and Miquelon. Latin America comprises Middle America (Mexico, the nations of Central America, and the Caribbean) and South America.

Rate of increase

Main article: Population growth
Population evolution in different continents. The vertical axis is logarithmic and is millions of people.

Different regions have different rates of population growth. According to the above table, the growth in population of the different regions from 2000 to 2005 was:

237.771 million in Asia
92.293 million in Africa
38.052 million in Latin America
16.241 million in Northern America
1.955 million in Oceania
-3.264 million in Europe
383.047 million in the whole world

In the 20th century, the world saw the biggest increase in its population in human history due to lessening of the mortality rate in many countries due to medical advances and massive increase in agricultural productivity attributed to the Green Revolution.[24][25][26]

In 2000, the United Nations estimated that the world's population was growing at the rate of 1.14% (or about 75 million people) per year,[27] down from a peak of 88 million per year in 1989. In the last few centuries, the number of people living on Earth has increased many times over. By the year 2000, there were 10 times as many people on Earth as there were 300 years ago. According to data from the CIA's 2005–2006 World Factbooks, the world human population increased by 203,800 every day.[28] The CIA Factbook increased this to 211,090 people every day in 2007, and again to 220,980 people every day in 2009.

Map of countries and territories by fertility rate

Globally, the population growth rate has been steadily declining from its peak of 2.19% in 1963, but growth remains high in Latin America, the Middle East and Sub-Saharan Africa.[29]

In some countries there is negative population growth (i.e. net decrease in population over time), especially in Central and Eastern Europe (mainly due to low fertility rates) and Southern Africa (due to the high number of HIV-related deaths). Within the next decade, Japan and some countries in Western Europe are also expected to encounter negative population growth due to sub-replacement fertility rates.

The United Nations states that population growth is rapidly declining due to the demographic transition. The world population is expected to peak at 9.2 billion in 2050.[2]

Population (est.) 10,000 BC–2000 AD.

Population (est.) 10,000 BC–2000 AD in log y scale

World population 1950–2000

Increase rate 1950–2000

Models

Hoerner (1975) proposed the following formula:[30]

N = \frac{C}{T_0-T}

where

  • N is current population
  • T is the current year
  • C = 2·1011
  • T0 = 2025

but this represents hyperbolic growth with an infinite population in 2025.

According to Kapitza (1997)[31], the population grew between 67000 b.c. and 1965, and the word population growth formula is:

N = \frac{C}{\tau} \arccot \frac{T_0-T}{\tau}

where

  • N is current population
  • T is the current year
  • C = (1.86±0.01)·1011
  • T0 = 2007±1
  • τ = 42±1

The transition from hyperbolic growth to slower rates of growth is called demographic transition.

Milestones

World Population Milestones (Billions - estimated).
World population estimates milestones .
Population
(in billions)		 1 2 3 4 5 6 7 8 9
Year 1804 1927 1959 1974 1987 1999 2012 2025 2040
Years elapsed 123 32 14.75 13.25 12.25 12.33 13 15

There is currently no estimation on the exact day the world's population surpassed both the 1 and 2 billion marks. The day of 3 and 4 billion were not officially celebrated, but the International Database of the U.S. Census Bureau places them around July 1959, and April 1974. The United Nations did determine, and celebrate, the "Day of 5 billion" (July 11, 1987), and the "Day of 6 billion" (October 12, 1999). The U.S. Census bureau, International Programs division, currently estimated that the world reached 6 billion on April 21, 1999 (several months earlier than the official UN day). The "Day of 7 billion" has been targeted by the Census Bureau to be in February 2012.[32]

Years for Population to Double

Including some more estimates (together with an interpolated number for year 950), the world population has been doubled or will double in the following years (with two different starting points). Note how, during the 2nd millennium, each doubling has taken roughly half as long as the previous doubling. However, it is unlikely that there will be another doubling in the current century.[33]

Years for Population to Double
Starting at 250 million Starting at 375 million
Population
(in billions)		 0.25 0.5 1 2 4 8 0.375 0.75 1.5 3 6
Year 950 1600 1804 1927 1974 2025 1420 1720 1875 1959 1999
Years elapsed 650 204 123 47 51 300 155 84 40

Distribution

Population density map of the world in 1994, when the world's population was 5.6 billion; Observe the high densities in the Indo-Gangetic and North China plains, the Sichuan Basin, the Nile river delta, Southern Japan, Western Europe, Java, and the Boston-Washington corridor.
Main article: Population density

Asia accounts for over 60% of the world population with almost 3.8 billion people. The People's Republic of China and India alone comprise 20% and 17% respectively. Africa follows with 840 million people, 12% of the world's population. Europe's 710 million people make up 11% of the world's population. North America is home to 514 million (8%), South America to 371 million (5.3%), and Australia to 21 million (0.3%).

The world's most populous nations

Further information: List of countries and dependencies by population density and List of countries by population


Map of countries by population
The 10 most densely populated countries
Rank Country Population Area (km²) Density (Pop per km²) Notes
1 Flag of Monaco Monaco 32,719 1.95 16,779 [34]
2 Flag of Singapore Singapore 4,620,657 707.1 6,535
3 Flag of the Vatican City Vatican City 824 0.44 1,873 [35]
4 Flag of the Maldives Maldives 385,375 298 1,293
5 Flag of Malta Malta 404,032 316 1,279
6 Flag of Bahrain Bahrain 723,967 665 1,089 [36]
7 Flag of Bangladesh Bangladesh 155,688,660 147,570 1,055 [37]
8 Palestinian flag Palestinian territories 4,223,760 6,020 702
9 Flag of Nauru Nauru 13,918 21 663
10 Flag of the Republic of China Republic of China ("Taiwan") 22,955,395 36,190 634 [35]


Population by region, 2007
The 16 countries with the largest total population:
Rank Country / Territory Population Date  % of world population Source
1  China
(excluding Hong Kong and Macau)		 1,329,740,000 March 25, 2009 19.66% Chinese Population Clock[38]
2  India 1,145,174,000 02009-03-03 March 3, 2009 16.94% Indian Population clock
—  European Union 499,673,300 02009-01-01 January 1, 2009 7.39% Eurostat estimate
3  United States 305,924,270 02009-03-02 March 2, 2009 4.53% Official USA Population clock
4  Indonesia 229,631,355 02009-03-03 March 3, 2009 3.4% Indonesian Population clock
5  Brazil 190,765,170 02009-03-03 March 3, 2009 2.82% Brazilian Population clock
6  Pakistan 166,137,500 02009-04-15 April 15, 2009 2.45% Pakistani Population clock
7  Bangladesh 155,688,660 02009-03-02 March 2, 2009 2.3% Private Bangladeshi Population clock
8  Nigeria 148,235,170 2.19% UN estimate
9  Russia 141,849,333 02009-03-03 March 3, 2009 2.1% Russian Population Clock
10  Japan 127,170,110 02009-03-02 March 2, 2009 1.88% Japanese Statistics Bureau
11  Mexico 111,077,375 02009-03-02 March 2, 2009 1.64% Private Mexican Population Clock
12  Philippines 93,843,460 02009-03-02 March 2, 2009 1.39%

Private Filipino Population Clock
13  Vietnam 86,709,095 02009-03-02 March 2, 2009 1.28%

Private Vietnamese Population Clock
14  Germany 82,060,000 02008-12 December 2008 1.21% Federal Statistical Office of Germany
15  Ethiopia 79,221,000 02008-07 July 2008 1.18%

Ethiopia Central Statistics Agency
16  Egypt 75,973,137 02009-03-03 March 3, 2009 1.12%

Egyptian Population Clock

Approximately 4.51 billion people live in these 16 countries, representing roughly two-thirds (66.7%) of the world's population as of February 2009.


Countries ranking in the top 40 both in terms of total population (more than 29 million people) and population density (more than 310 people per square kilometer):
Country Population Density (Pop. per km²) Notes
India 1,160,139,960 352.9 Second largest country
Bangladesh 155,688,660 1,055.0 Largest fast growing country
Japan 127,170,110 336.5 Declining in population
Philippines 93,843,460 312.8 Fast growing country
South Korea 49,354,980 493.4 Steady in population

Ethnicity

Main article: List of ethnic groups

The world is made up of thousands of ethnic groups. The single largest ethnic group on the planet by far is Han Chinese, which represents 19.73% of the global population. For comparison 6.06% of the planet's population is of full or partial Spanish ancestry, and on a wider scale 14.2% of earth's population is of Sub-Saharan descent (those identifying as 'Black')[citation needed].

Demographics of youth

According to the 2006 CIA World Factbook, around 27% of the world's population is below 15 years of age.[39]

Before adding mortality rates, the 1990s saw the greatest number of raw births worldwide, especially in the years after 1995, despite the fact that the birth rate was not as high as in the 1960s. In fact, because of the 163 million-per-year raw births after 1995, the time it took to reach the next 109 reached its fastest pace (only 12 years), as world population reached 6 billion people in 1999, when at the beginning of the decade, the reaching was designated for the year 2000, by most demographers. These people aged 9 through 18 make up these births today, and are either from the late Generation Y group, or are in the Generation Z group.

1985–1990 marked the period with the fastest yearly population change in world history. Even though the early 1960s had a greater growth rate than in the mid and late 1980s, the population change hovered around 83 million people in the five-year period, with an all-time growth change of nearly 88 million in 1990. The reason is that the world's population was greater in the mid- and late-1980s (around 5 billion) than in the early 1960s (around 3 billion), which meant that the growth rate in the 1980s was no factor on the dramatic population change. People aged 19 to 24 make up these births today, and are a part of Generation Y.

Forecast

Main article: World population estimates
See also: Overpopulation
UN (medium variant, 2008 rev.) and U.S. Census Bureau (June 2009) estimates[40][41]
Year UN est
(billions)		 Diff. US est
(billions)		 Diff.
2000 6.1 - 6.0 -
2010 6.9 0.8 6.8 0.8
2020 7.7 0.8 7.6 0.8
2030 8.3 0.6 8.3 0.7
2040 8.8 0.5 8.8 0.5
2050 9.1 0.3 9.3 0.5

In the long run, the future population growth of the world is difficult to predict and the UN and US Census Bureau give different estimates. Birth rates are declining slightly on average, but vary greatly between developed countries (where birth rates are often at or below replacement levels), developing countries, and different ethnicities. Death rates can change unexpectedly due to disease, wars and catastrophes, or advances in medicine. The UN itself has issued multiple projections of future world population, based on different assumptions. Over the last 10 years, the UN had consistently revised these projections downward, until the 2006 revision issued March 14, 2007 revised the 2050 mid-range estimate upwards by 273 million.

The United States Census Bureau issued a revised forecast for world population that increased its projection for the year 2050 to above 9.4 billion people (which was the UN's 1996 projection for 2050), up from 9.1 billion people. A new US Census Bureau revision from June 18, 2008 has increased its projections further, to beyond 9.5 billion in 2050.

Other projections are that the world's population will eventually crest, though it is uncertain when or how. In some scenarios, it will crest as early as around 2050 at under 9 billion, or 10 to 11 billion, due to gradually decreasing birth rates.[16]

In other scenarios, disasters triggered by the growing population's demand for scarce resources will eventually lead to a sudden population crash, or even a Malthusian catastrophe (also see overpopulation and food security).

UN estimates (in thousands).[16][18][42]
Year World Africa Asia Europe Latin America US and Canada Oceania
2000 6,070,581 795,671 (13.1%) 3,679,737 (60.6%) 727,986 (12.0%) 520,229 (8.6%) 315,915 (5.2%) 31,043 (0.5%)
2005 6,453,628 887,964 (13.8%) 3,917,508 (60.7%) 724,722 (11.2%) 558,281 (8.7%) 332,156 (5.1%) 32,998 (0.5%)
2010 6,830,283 984,225 (14.4%) 4,148,948 (60.7%) 719,714 (10.5%) 594,436 (8.7%) 348,139 (5.1%) 34,821 (0.5%)
2015 7,197,247 1,084,540 (15.1%) 4,370,522 (60.7%) 713,402 (9.9%) 628,260 (8.7%) 363,953 (5.1%) 36,569 (0.5%)
2020 7,540,237 1,187,584 (15.7%) 4,570,131 (60.6%) 705,410 (9.4%) 659,248 (8.7%) 379,589 (5.0%) 38,275 (0.5%)
2025 7,851,455 1,292,085 (16.5%) 4,742,232 (60.4%) 696,036 (8.9%) 686,857 (8.7%) 394,312 (5.0%) 39,933 (0.5%)
2030 8,130,149 1,398,004 (17.2%) 4,886,647 (60.1%) 685,440 (8.4%) 711,058 (8.7%) 407,532 (5.0%) 41,468 (0.5%)
2035 8,378,184 1,504,179 (18.0%) 5,006,700 (59.8%) 673,638 (8.0%) 731,591 (8.7%) 419,273 (5.0%) 42,803 (0.5%)
2040 8,593,591 1,608,329 (18.7%) 5,103,021 (59.4%) 660,645 (8.0%) 747,953 (8.7%) 429,706 (5.0%) 43,938 (0.5%)
2045 8,774,394 1,708,407 (19.5%) 5,175,311 (59.0%) 646,630 (7.4%) 759,955 (8.7%) 439,163 (5.0%) 44,929 (0.5%)
2050 8,918,724 1,803,298 (20.2%) 5,217,202 (58.5%) 653,323 (7.3%) 767,685 (8.6%) 447,931 (5.0%) 45,815 (0.5%)

Predictions based on population growth

In 1798 Thomas Malthus incorrectly predicted that population growth would outrun food supply by the mid 19th century. In 1968, Paul R. Ehrlich reprised this argument in The Population Bomb, predicting famine in the 1970s and 1980s. The dire predictions of Ehrlich and other neo-Malthusians were vigorously challenged by a number of economists, notably Julian Lincoln Simon. Agricultural research already under way, such as the green revolution, led to dramatic improvements in crop yields. Food production has kept pace with population growth, but Malthusians point out the green revolution relies heavily on petroleum-based fertilizers, and that many crops have become so genetically uniform that a crop failure would be very widespread. Food prices in the early 21st century are rising sharply on a global scale, and causing serious malnutrition to spread widely.[43]

From 1950 to 1984, as the Green Revolution transformed agriculture around the world, grain production increased by 250%. The energy for the Green Revolution was provided by fossil fuels in the form of fertilizers (natural gas), pesticides (oil), and hydrocarbon-fueled irrigation.[44] The peaking of world hydrocarbon production (Peak oil) may test Malthus and Ehrlich critics.[45][46] As of May 2008, the price of grain has been pushed up by increased farming for use in biofuels,[47] world oil prices at over $140 per barrel,[48] global population growth,[49] climate change,[50] loss of agricultural land to residential and industrial development,[51][52] and growing consumer demand in China and India[53][54]. Food riots have recently occurred in many countries across the world.[55][56][57]

The world population has grown by about four billion since the beginning of the Green Revolution and most believe that, without the Revolution, there would be greater famine and malnutrition than the UN presently documents (approximately 850 million people suffering from chronic malnutrition in 2005).[58]

Number of humans who have ever lived

In the 1970s it was popular to believe that 75% of all the people who had ever lived were alive in the 1970s, which would have put the total number of people who ever lived as of the 1970s as less than the current number of people alive today. This view was eventually debunked as a myth.[59] A more recent estimate of the total number of people who have ever lived was prepared by Carl Haub of the Population Reference Bureau in 1995 and subsequently updated in 2002; the updated figure was approximately 106 billion.[60][61] Haub characterized this figure as an estimate which required "selecting population sizes for different points from antiquity to the present and applying assumed birth rates to each period".[61] Given an estimated global population of 6.2 billion in 2002, it could be inferred that about 6% of all people who had ever existed were alive in 2002.[60]

Other estimates of the total number of people who have ever lived range approximately from 45 billion to 125 billion, with the more robust of these falling in the 90–110 billion range.[citation needed] It is difficult to estimate for the following reasons:[citation needed]

  • The set of specific characteristics which define a human being and distinguish early Homo sapiens from earlier or related species continues to be a subject of intense research and debate. It is thus not possible to know when to begin the count, nor which hominids to include. See in this regard also Sorites paradox.
  • Even if the scientific community reached wide consensus regarding which characteristics distinguished human beings, it would be nearly impossible to pinpoint the time of their first appearance to even the nearest millennium because the fossil record is simply too sparse. Only a few thousand fossils of early humans have been found, most no bigger than a tooth or a knucklebone. These bone fragments are used to extrapolate the population distribution of millions of early human beings spread across the continents.
  • Robust statistical data only exist for the last two or three centuries. Until the late 18th century, few nations, kingdoms, or empires had ever performed an accurate census. In many early attempts, such as Ancient Egypt and in the Persian Empire the focus was on counting merely a subset of the people for purposes of taxation or military service.[62] All claims of population sizes preceding the 18th century are estimates, and thus the margin of error for the total number of humans who have ever lived should be in the billions, or even tens of billions of people.
  • A critical item for the estimation is life expectancy. Using a figure of 20 years and the population estimates above, one can compute about 58 billion. Using a figure of 40 yields half of that. Life expectancy varies greatly when taking into account children who died within the first year of birth, a number very difficult to estimate for earlier times.

See also

Further resources

  • There is a map that is rescaled in order to display every country according to its population size. It is available at the University of Sheffield Worldmapper.[63]
  • Population patterns and trends can be explored on the GeoHive interactive world atlas.[64]

References

  1. ^ U.S. Census Bureau - World POPClock Projection
  2. ^ World population estimates
  3. ^ World Population Clock — Worldometers
  4. ^ International Data Base (IDB) — World Population
  5. ^ Population estimates of the Roman Empire, Dr. Kenneth W. Harl
  6. ^ "Plague, Plague Information, Black Death Facts, News, Photos – National Geographic". Science.nationalgeographic.com. http://science.nationalgeographic.com/science/health-and-human-body/human-diseases/plague-article.html. Retrieved on 2008-11-03. 
  7. ^ "Historical Estimates of World Population". Census.gov. http://www.census.gov/ipc/www/worldhis.html. Retrieved on 2008-11-03. 
  8. ^ Ming Dynasty. MSN.com.
  9. ^ China's Population: Readings and Maps. Columbia University, East Asian Curriculum Project.
  10. ^ The Story Of... Smallpox – and other Deadly Eurasian Germs. Public Broadcasting Service (PBS).
  11. ^ Stacy Goodling, "Effects of European Diseases on the Inhabitants of the New World"
  12. ^ Population crises and cycles in history. A review of the book Population Crises and Population cycles by Claire Russell and W.M.S. Russell.
  13. ^ Mabel C. Buer, Health, Wealth and Population in the Early Days of the Industrial Revolution, London: George Routledge & Sons, 1926, page 30 ISBN 0-415-38218-1
  14. ^ Modernization - Population Change. Encyclopædia Britannica.
  15. ^ Reintegrating India with the World Economy. Peterson Institute for International Economics.
  16. ^ a b c World population prospects: the 2004 revision population database
  17. ^ The World at un.org
  18. ^ a b Population Growth over Human History
  19. ^ Geo Hive: the population of continents, regions and countries (Jul. 1, 2008)
  20. ^ UN report 2004 data
  21. ^ fewer than 15,000 individuals according to the Toba catastrophe theory; see also Humans lived in tiny, separate bands for 100,000 years (breitbart.com)
  22. ^ a b c an average of figures from different sources as listed at the US Census Bureau's Historical Estimates of World Population; see also *Kremer, Michael. 1993. "Population Growth and Technological Change: One Million B.C. to 1990," The Quarterly Journal of Economics 108(3): 681-716.
  23. ^ The range of figures from different sources as listed at the US Census Bureau's Historical Estimates of World Population put the population at 1 AD between 170 million to 400 million.
  24. ^ The limits of a Green Revolution?
  25. ^ The Real Green Revolution
  26. ^ World Population to 2300 Economic and Social Affairs, United Nations, 2004
  27. ^ census.gov
  28. ^ Current world population (ranked)
  29. ^ Ron Nielsen, The little green handbook, Picador, New York (2006) ISBN 0-312-42581-3
  30. ^ Hoerner, von S. Journal of British Interplanetary Society 28691 (1975)
  31. ^ Sergei P Kapitza. The phenomenological theory of world population growth. Physics-Uspekhi 39(1) 57-71 (1996).
  32. ^ "World Pop Clock Note". http://www.census.gov/ipc/www/popwnote.html. 
  33. ^ Letters to Nature: Doubling of world population unlikelyNature, 19 June 1997
  34. ^ The Monaco government uses a smaller surface area figure resulting in a population density of 18,078 per km².
  35. ^ a b Population density calculated using surface area and population figures from the CIA World Factbook.
  36. ^ mohammed al a'ali (April 1, 2008), Population surge 'threat to economy', gulf Daily News, http://gulf-daily-news.com/Story.asp?Article=213323&Sn=BNEW&IssueID=31012, retrieved on 2008-04-21 
  37. ^ Latest figure from the World Bank Development Indicators Database is 1,090 per km².
  38. ^ Hong Kong's population statistic is maintained separately by Census and Statistics Department of the Hong Kong Government, while Macau's population statistic is maintained by [ Statistics and Census Service of the Macau Government
  39. ^ Age structure of the world – 2006 CIA World Factbook
  40. ^ World Population Prospects - The 2008 Revision Population Database
  41. ^ U.S. Census Bureau — International Data Base (IDB)
  42. ^ The World at Six Billion
  43. ^ "Assessing the global food crisis". BBC. http://news.bbc.co.uk/1/hi/in_depth/7361945.stm. 
  44. ^ "Eating Fossil Fuels". Energy Bulletin. http://www.energybulletin.net/281.html. 
  45. ^ "Peak Oil: the threat to our food security". Soil Association. http://www.soilassociation.org/peakoil. 
  46. ^ "Peak Oil And Famine: Four Billion Deaths". Countercurrents. http://www.countercurrents.org/goodchild291007.htm. 
  47. ^ "2008: The year of global food crisis". Sunday Herald. http://www.sundayherald.com/news/heraldnews/display.var.2104849.0.2008_the_year_of_global_food_crisis.php. 
  48. ^ The global grain bubble
  49. ^ Food crisis will take hold before climate change, warns chief scientist
  50. ^ Global food crisis looms as climate change and fuel shortages bite
  51. ^ Experts: Global Food Shortages Could ‘Continue for Decades'
  52. ^ Has Urbanization Caused a Loss to Agricultural Land?
  53. ^ The World's Growing Food-Price Crisis
  54. ^ The cost of food: Facts and figures
  55. ^ Riots and hunger feared as demand for grain sends food costs soaring
  56. ^ Already we have riots, hoarding, panic: the sign of things to come?
  57. ^ Feed the world? We are fighting a losing battle, UN admits
  58. ^ The limits of a Green Revolution?
  59. ^ Population Reference Bureau
  60. ^ a b Curtin, Ciara (2007-03-01), "Fact or Fiction?: Living People Outnumber the Dead", Scientific American (Scientific American, Inc.) 297 (3): 126, September 2007, http://www.sciam.com/article.cfm?id=fact-or-fiction-living-outnumber-dead, retrieved on 2008-08-04  Note: text of paper publication slightly different than text of on-line publication
  61. ^ a b Haub, Carl (November/December 2002), "How Many People Have Ever Lived on Earth?", Population Today (Population Reference Bureau) 30 (8): 3–4, http://www.prb.org/pdf/PT_novdec02.pdf, retrieved on 2008-08-04 
  62. ^ Kuhrt, A. (1995) The Ancient Near East c. 3000–330BC Vol 2 Routledge, London. p. 695.
  63. ^ "Worldmapper image". http://www.worldmapper.org/imagemaps/imagemap2.html. ; "Worldmapper description". University of Sheffield. http://www.sasi.group.shef.ac.uk/worldmapper/display.php?selected=2. 
  64. ^ Global Statistics interactive atlas, GeoHive.

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