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Global Environmental History in the Age of Fossil Fuels

J.R. McNeill
Georgetown University

III. Population and Urbanisation as Ecological Trends

The age of fossil fuels coincided with an age of unprecedented population growth. In the millennium between Caesar and Saladin global population grew at a rate of about 0.01% per year. The raw data on growth rates are as follows:

Table 1
Annual Rates of Global Population Growth since AD 1000
1000–1500
  0.1%
1500–1820
  0.27%
1820–1870
  0.40%
1870–1913
  0.80%
1913–1950
  0.93%
1950–1973
  0.93%
1973–2001
  0.62%
Source: Maddison, The World Economy: Historical Statistics (Paris: OECD 2003), 257

And on global population size:

Table 2
Global Population since AD 1000 (millions)
1000
  268
1500
  438
1600
  556
1700
  603
1820
  1,041
1870
  1,271
1913
  1,791
1950
  2,524
1973
  3,916
2001
  6,149
Source: Maddison, The World Economy: Historical Statistics (Paris: OECD 2003), 256

For reasons that have been much debated, global population began to edge upwards in the second millennium, and to gather pace in the 18th century. Slightly lower death rates took hold, perhaps a result of ecological adjustment to some infectious diseases, perhaps a matter of improved nutrition and famine reduction. Then, in the course of the 19th century, population growth rates accelerated, despite difficult times in China and India.

That acceleration nearly stalled in the years 1913-50, presumably a consequence of wars and economic depression. But after 1950, politics, public health and perhaps other factors combined to create a crescendo of demographic growth, briefly topping 2% per annum in the 1960s and 1970s.

over population

Human numbers more than doubled between 1950 and 2000. In no other period of 50 years, in no other century, did human numbers ever double (nor will they again). These modern growth rates are 50 to 200 times as fast as those that prevailed for most of our species’ history. No other primate, probably no other mammal, has ever done anything like this in the history of life on earth.

At the same time, our species has changed its characteristic habitat from countryside to city. The first cities appeared 6,000-7,000 years ago, contained a few thousand people at most and were local in importance. Not until 8th-century Baghdad did any city reach a million, and that achievement did not last.

As late as 1500 no city exceeded 700,000 (the seven largest were in Asia or Egypt). By 1800, Beijing alone had topped 1 million. 9 Only about 3% of humankind lived in cities. There were good reasons for this: supplying a concentrated population with enough food and fuel was a difficult technical and economic problem.

Cities in temperate latitudes (northern Europe or China) needed forest areas 50 to 200 times as large as to meet their fuel wood needs. 10 This put a fairly firm limit on urbanisation. So did constraints upon agricultural productivity.

After 1800, however, the development of fossil fuels reduced the requirements for fuel wood and, with technical improvements in engines and transport, allowed cities to extend their footprint, or catchment, over greater distances. By 1900 about 14% of people lived in cities, and by 2000 very close to 50%.

Thus the proportion of urban-dwellers among our species quadrupled in the 19th century and tripled in the 20th. In raw numbers, the urban population in 1800 was about 30 million, in 1900, 225 million, and in 2000, 3 billion.

This comes to a 100-fold expansion in 200 years, roughly the same as the expansion in energy use. Nothing like this ever happened in human history, nor can it again.

Until a century ago, cities were lethal environments. Their infectious diseases killed people faster than others were born, so that cities survived only on the basis of continuing inward migration from rural regions. London around 1750, for example, killed off half of the population increase of the rest of England.

Yet villages produced enough migrants that London survived, and even grew, intermittently and slowly. But between 1850 and 1930 sanitation improvements revolutionised urban demography, so that after 7,000 years as sinkholes for humanity, cities by the early 20th century actually contributed to population growth rather than pruning it.

Rural landscapes continued to send their legions of young migrants to the world’s cities, more of them than ever before survived and reproduced; hence the emergence of megalopoli (cities with more than 10 million) and the urbanisation of our species.

For our first few hundred thousand years on earth, our characteristic habitat was savanna grasslands and parklands. For a brief span, maybe 5000BC to AD 2000, the farming village formed the standard human habitat. But now, for the first time, the typical human animal has become a city dweller.

continue to: IV. Ecological Changes

                   V. Environmentalism

                   VI. Conclusion

or return to index

9Tertius Chandler, Four Thousand Years of Urban Growth: An Historical Census (St. David's University Press, 1987)

10Smil, Energies, 118

Date posted: 30/11/07

 

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