Human population

The world population is the total number of humans on Earth at a given time. As of May 2008, the world's population is believed to be just over 6.6 billion.^[1]^[2] In line with population projections, this figure continues to grow at rates that were unprecedented before the 20th century, although the rate of increase has almost halved since its peak, which was reached in 1963, of 2.2 percent per year. The world's population, on its current growth trajectory, is expected to reach nearly 9 billion by the year 2050.

Population figures

Censuses taken between 300–400 CE^{dubious – discuss} showed over 50 million people living in the combined eastern and western Roman empire.^{citation needed}(citation Dr. Kenneth W. Harl, tulane.edu)

Below is a table with historical and predicted population figures shown in millions.^[3]^[4]^[5] The availability of historical population figures varies by region. (Note: These projections here are not kept up to date.) Please see World population estimates for more figures.

* Northern America indicates the northern countries and territories of North America: Canada, the United States, Greenland, Bermuda, and St. Pierre and Miquelon. This should not be confused with the term "North America" which typically includes Mexico. The United Nations data includes Mexico as part of Latin America.

Rate of increase

Different regions have different rates of population growth, but in the unusual case of the 20th century, the world saw the biggest increase in its population in human history due to medical advances and massive increase in agricultural productivity made by the Green Revolution.

In 2000, the United Nations estimated that the world's population was then growing at the rate of 1.14% (or about 75 million people) per year,^[10] down from a peak of 86 million per year in 1987. 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 than 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.^[11] The 2007 CIA factbook increased this to 211,090 people every day.

Population growth which exceeds the carrying capacity of an area or environment results in overpopulation. Conversely, such areas may be considered "underpopulated" if the population is not large enough to maintain an economic system; however, many who do not view overpopulation as a serious problem fail to consider the sustainability of economic systems, the environmental degradation caused, and the ecological footprint of the existing population.

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 2075.[1]

Milestones

The following shows estimates of when each billion milestone was or will be met:

These numbers show that the world's population has tripled in 72 years, and doubled in 38 years up to the year 1999. Including some more 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.

Population distribution

Population density map of the world in 1994, when the world's population was at 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, the Indonesian island of Java, Central America (especially El Salvador, the Americas' most densely populated nation), and the United States' BosWash megalopolis.

Asia accounts for over 60% of the world population with almost 3.8 billion people. People's Republic of China and India alone comprise 20% and 16% respectively. Africa follows with 840 million people, 12% of the world 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 21 million.

The 15 most populous nations

Approximately 4.3 billion people live in these 15 countries, representing roughly two-thirds of the world's population. If added together, all nations in the European Union, with 494 million people – about 7.3% of world's population in 2006 – would be third in the list above.

Ethnicity

The world is made up of hundreds of thousands of ethnic groups, and due to mass immigration across the planet over millenia, it is impossible to tell how many people belonging to a certain ethnic group inhabit the earth. 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').

Demographics of youth

According to the 2006 CIA World Factbook, around 27% of the world's population is below 15 years of age.^[13]

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 160 million-per-year raw births after 1995, the time it took to reach the next billion 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. People aged 7 through 17 make up these births, today.

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 because 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 17 to 22 make up these births, today.

Forecast of world population

In the long run, the future population growth of the world is difficult to predict. 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.

Alternately, 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. The latest Census Bureau estimates for the same upcoming years are as follows:^[14]

Other projections of population growth predict that the world's population will eventually crest, though it is uncertain exactly when or how. In some scenarios, the population will crest as early as the mid-21st century at under 9 billion, due to gradually decreasing birth rates, (the "low variant" of ^[3]), The "high variant" from the same source gives a population between 10 and 11 billion in 2050.

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 our growing population

In 1798, Thomas Malthus incorrectly predicted that population growth would eventually outrun food supply in the middle of the 19th century, resulting in catastrophe. In 1968, Paul R. Ehrlich reignited this argument with his book The Population Bomb, which helped give the issue significant attention throughout the 1960s and 1970s. The dire predictions of Ehrlich and other neo-Malthusians were vigorously challenged by a number of economists, notably Julian Simon.

Child poverty has been linked to people having children before they have the means to care for them.^[18] More recently, some scholars have put forward the Doomsday argument applying Bayesian probability to world population to argue that the end of humanity will come sooner than we usually think.^[19]

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).^[34]

Number of humans who have ever lived

Estimates of the total number of people who have ever lived range approximately from 45 billion to 125 billion^{citation needed}. Many of the more robust estimates fall into the range of 90 to 110 billion humans^{citation needed}. It is impossible to make a precise count of the number of human beings who have ever lived for the following reasons:

"Guesstimating the number of people ever born... requires selecting population sizes for different points from antiquity to the present and applying assumed birth rates to each period..."^[35]

The claim that more than half the humans ever born are alive today is, in all probability, not accurate.

References

^ CIA's The World Factbook (see also The World Factbook)
^ World POPClock Projection, U.S. Census Bureau
^ ^a ^b ^c World population prospects: the 2004 revision population database
^ The World at un.org
^ Population Growth over Human History
^ UN report 2004 data
^ http://www.breitbart.com/article.php?id=080425101050.cni2ks3u&show_article=1
^ ^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.
^ 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 CE between 170 million to 400 million.
^ census.gov
^ Current world population (ranked)
^ Ron Nielsen, The little green handbook, Picador, New York (2006) ISBN 0-312-42581-3
^ Age structure of the world — 2006 CIA World Factbook
^ U.S. Census Bureau - International Data Base (IDB)
^ The World at Six Billion
^ Population Growth over Human History
^ The Death of the West: How Dying Populations and Immigrant Invasions Imperil Our Country and Civilization (ISBN 0-312-30259-3), by Patrick Buchanan, The Empty Cradle: How Falling Birthrates Threaten World Prosperity (ISBN 0-465-05050-6), by Longman, and Fewer: How the New Demography of Depopulation Will Shape Our Future (ISBN 1-56663-606-X), by Wattenberg
^ Population bomb still ticking away - 20 Mar 2007 - NZ Herald
^ DIE OFF - a population crash resource page
^ Eating Fossil Fuels |EnergyBulletin.net
^ Peak Oil: the threat to our food security
^ Peak Oil And Famine:Four Billion Deaths
^ 2008: The year of global food crisis
^ The global grain bubble
^ Food crisis will take hold before climate change, warns chief scientist
^ Global food crisis looms as climate change and fuel shortages bite
^ Experts: Global Food Shortages Could ‘Continue for Decades'
^ Has Urbanization Caused a Loss to Agricultural Land?
^ The World's Growing Food-Price Crisis
^ The cost of food: Facts and figures
^ Riots and hunger feared as demand for grain sends food costs soaring
^ Already we have riots, hoarding, panic: the sign of things to come?
^ Feed the world? We are fighting a losing battle, UN admits
^ The limits of a Green Revolution?
^ ^a ^b How Many People Have Ever Lived on Earth? by Carl Haub, 2002; calculated from a start date of 50 000 years BCE.

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