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Monday, June 21, 2010

FORECAST


UN (medium variant, 2008 rev.) and US Census Bureau (January 2010) estimates
Year
UN est
(millions)
Diff.
US est
(millions)
Diff.
2000
6,115
-
6,084
-
2010
6,909
794
6,831
747
2020
7,675
766
7,558
727
2030
8,309
634
8,202
644
2040
8,801
492
8,749
547
2050
9,150
349
9,202
453








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. According to the latter, world population will hit seven billion in July 2012 or by late 2011, according to UN prediction.
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 has issued multiple projections of future world population, based on different assumptions. Over the last ten years, the UN has consistently revised these projections downward, until the 2006 revision issued March 14, 2007 revised the 2050 mid-range estimate upwards by 273 million.
In some 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 2008 estimates and medium variant projections (in millions).
Year
World
Asia
Africa
Europe
Latin America
Northern America
Oceania
2000
6,115
3,698 (60.5%)
819 (13.4%)
727 (11.9%)
521 (8.5%)
319 (5.2%)
31 (0.5%)
2005
6,512
3,937 (60.5%)
921 (14.1%)
729 (11.2%)
557 (8.6%)
335 (5.1%)
34 (0.5%)
2010
6,909
4,167 (60.3%)
1,033 (15.0%)
733 (10.6%)
589 (8.5%)
352 (5.1%)
36 (0.5%)
2015
7,302
4,391 (60.1%)
1,153 (15.8%)
734 (10.1%)
618 (8.5%)
368 (5.0%)
38 (0.5%)
2020
7,675
4,596 (59.9%)
1,276 (16.6%)
733 (9.6%)
646 (8.4%)
383 (5.0%)
40 (0.5%)
2025
8,012
4,773 (59.6%)
1,400 (17.5%)
729 (9.1%)
670 (8.4%)
398 (5.0%)
43 (0.5%)
2030
8,309
4,917 (59.2%)
1,524 (18.3%)
723 (8.7%)
690 (8.3%)
410 (4.9%)
45 (0.5%)
2035
8,571
5,032 (58.7%)
1,647 (19.2%)
716 (8.4%)
706 (8.2%)
421 (4.9%)
46 (0.5%)
2040
8,801
5,125 (58.2%)
1,770 (20.1%)
708 (8.0%)
718 (8.2%)
431 (4.9%)
48 (0.5%)
2045
8,996
5,193 (57.7%)
1,887 (21.0%)
700 (7.8%)
726 (8.1%)
440 (4.9%)
50 (0.6%)
2050
9,150
5,231 (57.2%)
1,998 (21.8%)
691 (7.6%)
729 (8.0%)
448 (4.9%)
51 (0.6%)

 

FORECASTS BY REGION

Below is a table with historical and predicted population figures shown in millions.
The availability of historical population figures varies by region.
World historical and predicted populations (in millions)
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↓↓
2100↓↓
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 millions) 
Year
World

70,000 BCE
< 1







10,000 BCE
1







9000 BCE
3







8000 BCE
5







7000 BCE
7







6000 BCE
10







5000 BCE
15







4000 BCE
20







3000 BCE
25







2000 BCE
35







1000 BCE
50







500 BCE
100







1 CE
200







1000 CE
310







1750 CE
791
106
502
163
16
2
2

1800 CE
978
107
635
203
24
7
2

1850 CE
1,262
111
809
276
38
26
2

1900 CE
1,650
133
947
408
74
82
6

1950 CE
2,519
221
1,398
547
167
172
12.8

1955 CE
2,756
247
1,542
575
191
187
14.3

1960 CE
2,982
277
1,674
601
209
204
15.9

1965 CE
3,335
314
1,899
634
250
219
17.6

1970 CE
3,692
357
2,143
656
285
232
19.4

1975 CE
4,068
408
2,397
675
322
243
21.5

1980 CE
4,435
470
2,632
692
361
256
22.8

1985 CE
4,831
542
2,887
706
401
269
24.7

1990 CE
5,263
622
3,168
721
441
283
26.7

1995 CE
5,674
707
3,430
727
481
299
28.9

2000 CE
6,070
796
3,680
728
520
316
31.0

2005 CE
6,454
888
3,917
725
558
332
32.9

Jul. 1, 2008
6,707
973
4,054
732
577
337
34.3

Year
World

The figures for North and Central America only refer to post-European contact settlers, and not native populations from before European settlement.

MATHEMATICAL APPROXIMATIONS

However (1975) proposed the following formula:
N = \frac{C}{T_0-T}
where
§     N is current population
§     T is the current year
§     C = 2·1011
§     T0 = 2025
which represents hyperbolic growth with an infinite population in 2025.
According to Kapitsa (1997), the population grew between 67,000 BC and 1965, and the world 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 hyperboles to slower rates of growth is related to the demographic transition.

YEARS FOR WORLD 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.
Starting at 500 million
Population
(in billions)
0.5
1
2
4
8
Year
1500
1804
1927
1974
2025
Years elapsed
304
123
47
51


Starting at 375 million
Population
(in billions)
0.375
0.75
1.5
3
6
Year
1171
1715
1881
1960
1999
Years elapsed
544
166
79
39


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