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 , the Earth's
population is estimated by the
United States Census Bureau to be billion. The world population has been growing continuously since the end of the
Black Death around 1400. 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 at least 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. Because births outnumber deaths, the world's population is
expected to reach about 9 billion by the year 2040.
Population figures
A dramatic
population bottleneck is theorized for the period around 70,000 BC (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 (AD 300–400). The
Plague of Justinian caused
Europe's population to drop by around 50% between 541 and the 700s. The population of the world was more than 440 million in 1340. 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. It took roughly 200 years for Europe's population to regain its 1340 level.
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.
England's population reached an estimated 5.6 million in 1650, up from an estimated 2.6 million in 1500. New crops that had come to
Asia and
Europe from the Americas via the Spanish colonizers in the 16th century contributed to the population growth. Since being introduced by Portuguese traders in the 16th century,
maize and
manioc have replaced traditional
African crops as the continent’s most important staple food crops.
Alfred W. Crosby speculated that increased production of maize, manioc, and other
American crops "enabled the
slave traders drew many, perhaps most, of their cargoes from the rain forest areas, precisely those areas where American crops enabled heavier settlement than
before."
thumb|Scholars estimate that between 900,000 and 18 million people inhabited North America north of present-day Mexico at the time of European contact.
Cities with at least one million inhabitants in 2006. In 1800, only 3% of the world's population lived in cities, a figure that has risen to 47% by the end of the twentieth century.
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. Over the centuries, the Europeans had developed high degrees of immunity to these diseases, while the indigenous peoples had no such immunity.
During the
Agricultural and
Industrial Revolutions, the
life expectancy of children increased dramatically. 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.
[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] Europe’s population doubled during the 18th century, from roughly 100 million to almost 200 million, and doubled again during the 19th century. The population growth became more rapid after the introduction of compulsory
vaccination and improvements in medicine and sanitation. As living conditions and health care improved during the 19th century, Britain's population doubled every 50 years. By 1801 the
population of England had grown to 8.3 million, and by 1901 had grown to 30.5 million.
The population of the
Indian subcontinent, which stood at about 125 million in 1750, had reached 389 million by 1941. The region is currently home to 1.5 billion people. The total number of inhabitants of
Java increased from about 5 million in 1815 to more than 130 million in the early 21st century.
Mexico's population has grown from 13.6 million in 1900 to about 112 million in 2009.
Below is a
table with historical and predicted
population figures shown in millions.
[: The 2008 Revision Population Database] The availability of historical population figures varies by region.
Rate of increase
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.
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, 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.
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.
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.
In 2006, the
United Nations stated that the rate of population growth is diminishing due to the
demographic transition. If this trend continues, the rate of growth may diminish to zero, concurrent with a world population plateau of 9.2 billion, in 2050. However, this is only one of many estimates published by the UN. In 2009, UN projections for 2050 range from about 8 billion to 10.5 billion.
Models
Hoerner (1975) proposed the following formula:
where
but this represents
hyperbolic growth with an infinite population in 2025.
According to
Kapitsa (1997)
[ Physics-Uspekhi 39(1) 57-71 (1996).], the population grew between 67000 BC and 1965, and the world population growth formula is:
where
The transition from hyperboles to slower rates of growth is called demographic transition
.Milestones
World Population Milestones (in billions, estimated).
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.Years for population to double
Using linear interpolation of the UNDESA estimates, 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, fitting the hyperbolic growth model mentioned above. However, it is unlikely that there will be another doubling in the current century.
Years for Population to Double
Distribution
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%). Most populous nations
Map of countries by population
Population by region, 2007
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. Ethnicity
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 17.0% of the global population.Demographics of youth
According to the 2006 CIA World Factbook, around 27% of the world's population is below 15 years of age.
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
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. It is estimated in February 2010 the world population will hit 7 billion. 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.[: the 2004 revision population database]
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).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.
From 1950 to 1984, as the Green Revolution transformed agriculture around the world, grain production increased by over 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. The peaking of world oil production (Peak oil) may test Malthus and Ehrlich critics. As of May 2008, the price of grain has been pushed up by increased farming for use in biofuels, world oil prices at over $140 per barrel ($880/m3), global population growth, climate change, loss of agricultural land to residential and industrial development, and growing consumer demand in China and India. Food riots have recently occurred in many countries across the world.
Growing populations, falling energy sources and food shortages will create the "perfect storm" by 2030, the UK government chief scientist has warned. He said food reserves are at a 50-year low but the world requires 50% more energy, food and water by 2030. The world will have to produce 70% more food by 2050 to feed a projected extra 2.3 billion people and as incomes rise, the United Nations' Food and Agriculture Organisation (FAO) said.
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).Number of humans who have ever lived
In the 1970s it was a popular belief 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. 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.[ ]Note: text of paper publication slightly different than text of on-line publication
[ 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.]
Other estimates of the total number of people who have ever lived range approximately from 100 billion to 115 billion. It is difficult to estimate for the following reasons:
- The set of specific characteristics which define a human 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. However, the limited size of population in early times compared to its recent size makes this source of uncertainty of limited importance.
- 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. 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
- Literacy (correlated with population growth)
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.
[; ]
- Population patterns and trends can be explored on the GeoHive interactive world atlas.
