World population

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Image:World population increase history.png

The world population is the total number of humans alive on the planet Earth at a given time. According to estimates published by the United States Census Bureau<ref>United States Census Bureau</ref>, the Earth's population hit 6.5 billion on Saturday, February 25,2006.<ref>Leonard, David. "World Population to hit 6.5 Billion on Saturday". February 24,2006. MSNBC</ref> In line with population projections, this figure continues to grow at rates that are unprecedented prior to the 20th century. Approximately one fifth of all humans that have existed in the last six thousand years are currently alive. By some estimates, there are now one billion (thousand million) young people in the world between the ages of 15 and 24.

1 The Day of 6 Billion
2 Rate of population increase
3 Forecast of world population
4 Doomsayers
5 Different continents
6 References
7 External links

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The Day of 6 Billion

The United Nations Population Fund designated October 12, 1999 as the approximate day on which world population reached six billion. It was officially designated The Day Of 6 Billion.

This was about 12 years after the world population reached five billion, in 1987. The child that has been proclaimed by the United Nations Population Fund and welcomed by the U.N. Secretary-General Kofi Annan as the six billionth baby, was born on the designated day two minutes after midnight, not in India or China, as might be expected, but to Fatima Nevic and her husband Jasminko in Sarajevo, Bosnia.

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Rate of population increase

Image:Population curve.png The last 70 years of the 20th century saw the biggest increase in the world's population in human history. The following table shows when each billion milestone was met:

1 billion was reached in 1802.
2 billion was reached 125 years later in 1927.
3 billion was reached 34 years later in 1961.
4 billion was reached 13 years later in 1974.
5 billion was reached 13 years later in 1987.
6 billion was reached 12 years later in 1999.

From the figures above, the world's population has tripled in 72 years, and doubled in 38 years up to the year of 1999.

Including a few more estimates (beginning with 250 million around AD 950 and ending with 8 billion in 2027), the world population was doubled by the following years (doubling times in parentheses):

AD 950 (650) 1600 (202) 1802 (125) 1927 (47) 1974 (50) 2027,

or (beginning with 375 million around year 1420):

1420 (300) 1720 (155) 1875 (86) 1961 (38) 1999.

Note how, during the 2nd millennium, each doubling has taken roughly half as long as the previous doubling.

Image:Reciprocal population.PNG

The UN estimated in 2000 that the world's population was then growing at the rate of 1.4 percent (or 91 million people) per year. This represents a decrease in the growth rate from its level in 1990, mostly due to decreasing birth rates.

The first five years of the twenty-first century saw something of a decline in the overall volume of population growth, with the world's population increasing at a rate of about 76 million people per year as of 2005.

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Forecast of world population

The future growth of population 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) and developing countries. 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 has consistently revised its world population projections downward.

Current projections by the UN's Population Division, based on the 2004 revision of the World Population Prospects database <ref>World population prospects: the 2004 revision population database</ref>, are as follows.

Year	Population (billions)
2010	6.8
2020	7.6
2030	8.2
2040	8.7
2050	8.9

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 10 billion, due to gradually decreasing birth rates.

In less optimistic 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).

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Doomsayers

In 1798, Thomas Malthus predicted that population growth would eventually outrun food supply, resulting in catastrophe. In 1968 Paul R. Ehrlich reignited this argument with his book The Population Bomb, which helped give the issue significant mindshare 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.

On the opposite end of the spectrum there are a number of doomsayers who argue that today's low fertility rates will have severe negative consequences: The Death of the West: How Dying Populations and Immigrant Invasions Imperil Our Country and Civilization (ISBN 0312302592), by Patrick Buchanan, The Empty Cradle: How Falling Birthrates Threaten World Prosperity (ISBN 0465050506), by Longman, and Fewer: How the New Demography of Depopulation Will Shape Our Future (ISBN 156663606X), by Wattenberg.

Child poverty has been linked to people having children before they have the means to care for them.

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 (toxic waste rather than food shortages).

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Different continents

Image:World population evolution.png The vertical axis of the chart above is in billions. The population figures in the table below are in thousands.

Year	World	Africa	Asia	Europe	Latin-America	North America	Oceania
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	3 021 475	277 398	1 701 336	604 401	218 300	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

2010	6 830 283	984 225	4 148 948	719 714	594 436	348 139	34 821
2015	7 197 247	1 084 540	4 370 522	713 402	628 260	363 953	36 569
2020	7 540 237	1 187 584	4 570 131	705 410	659 248	379 589	38 275
2025	7 851 455	1 292 085	4 742 232	696 036	686 857	394 312	39 933
2030	8 130 149	1 398 004	4 886 647	685 440	711 058	407 532	41 468
2035	8 378 184	1 504 179	5 006 700	673 638	731 591	419 273	42 803
2040	8 593 591	1 608 329	5 103 021	660 645	747 953	429 706	43 938
2045	8 774 394	1 708 407	5 175 311	646 630	759 955	439 163	44 929
2050	8 918 724	1 803 298	5 217 202	653 323	767 685	447 931	45 815