ABSTRACT
Many distinguished writers have studied the question whether food is a limiting factor for population growth. Since the time when Malthus started the debate some 200 years ago (see Malthus, 1967; Ricardo, 1964) thousands of books, research papers, and study reports have been published on the subject (Boserup, 1965, 1981; Clark, 1967; Clark and Has well, 1964; Livi Bacci, 1991). [1] Despite these intense efforts, we are still far from consensus. A screening of available literature on estimating the earth’s population carrying capacity reveals surprising diversity of results (see Table 10.1 ). Estimates of the earth's population carrying capacity during the past 100 years.
|
Source |
Earth’s maximum population carrying capacity |
Date |
|---|---|---|
|
Ravenstein (1891) |
6 billion |
1891 |
|
Penck (1925) |
7.7–9.5 billion |
1925 |
|
Pearson and Harper (1945) |
0.9–2.8 billion |
1945 |
|
Baade (1960) a |
30 billion |
1960 |
|
Clark (1967) b |
47–157 billion |
1967 |
|
Revelle (1967) a |
41 billion |
1967 |
|
Mückenhausen (1973) c |
35–40 billion |
1973 |
|
Buringh et al. (1977, 1975) |
2.7–6.7 billion |
1975 |
|
Westing (1981), Mann (1981) |
about 2 billion |
1981 |
|
Simon (1981), Kahn (1982) |
no meaningful limitation |
1982 |
|
FAO/UNFPA/IIASA d |
for 1975: 1.957–32.407 billion |
1982 |
|
(Higgins et al., 1982) |
for 2000: 3.590–33.195 billion |
|
|
Gilland (1983) a |
7.5 million |
1983 |
|
Resources for the Future (1984) |
6.1 billion |
1984 |
|
Marchetti (1978) |
1 trillion |
1978 |
|
World Hunger Program e |
2.8–5.5 billion |
1992 |
|
(Cohen, 1992) |
||
|
Ehrlich et al. (1993) |
< 5.5 billion |
1993 |
Estimates are based on very low estimates of average food caloric consumption. According to Norse (1992) the three estimates of the global population carrying capacity would be much lower, if an average grain consumption of 800 kilograms per year were applied. Baade’s estimate would be more than 18 billion; Revelle’s would be 14 billion; and Gilland’s would be 8.8 billion.
“If we take world resources of agricultural land at 10.7 billion hectares of standard land equivalent, this could feed, at maximum standards, 47 billion people. … For people living at Japanese standards of food consumption and Asian standards of timber requirements only 680 sq.m./person is required, and the world’s potential agricultural and forest land could supply the needs of 157 billion people.” See Clark (1967).
Miickenhausen’s estimate was based on a report of the US President’s Science Advisory Commitee in 1967 which analyzed the world’s production capacity of soils (US, 1967).
The FAO/UNFPA/IIASA study estimated the global population carrying capacity for 1975 and 2000 at three agricultural input levels (low, medium, high). For details see Appendix Tables 1 and 2 in Higgins et al. (1982).
“The World Hunger Program at Brown University estimated that, with present levels of food production and an equal distribution of food, the world could sustain either 5.5 billion vegetarians, 3.7 billion people who get 15 percent of their calories from animal products, … or 2.8 billion people who derive 25 percent of their calories from animal products” (Cohen, 1992).
Among other sources the author uses a compilation on “Estimates of Arable Land: Past Studies” in Shah et al. (1985).
