"...mein Acker ist die Zeit", Aufsätze zur Umweltgeschichte - Oapen

City and Nature (2007)
lived in cities; by 1900 this percentage had increased to 14 percent, and by 1975 to
30 percent.
In 2015 it is likely that 21 percent of the world’s human population will be
concentrated in metropolitan cities. It is remarkable that already today more than 70
percent of all cities with more than one million inhabitants (i.e. metropolitan cities)
are located in developing and threshold countries. Thus, urbanism has displaced
and outnumbered all other forms of human ecological conditions. Cities appeared
late in human history and started as relatively small communities. But it took only
10,000 years for this specific human invention to turn into by far most altering
impact of humans on the face of the earth (see Figure 1).
2 City and Nature
2.1 Baselines
The main feature of the biosphere is that processes are organized in cycles. 206 Those
cycles are interrupted or greatly changed in the urban organization of human life. Cities
require a set of prerequisites or determinants that need to be achieved by human societies
building them up. Disregarding societal features, the most important among these
prerequisites are a constant supply of fresh water and a nutritional and energy supply
for a high concentration of people, and therefore a need for waste and sewage disposal.
In terms of biology, a city is a very limited area of space, permanently inhabited
by a large number of people that use and/or exploit the adjacent and surrounding
areas, mostly beyond the carrying capacity level compared with human population
densities of hunter-gatherer or other nonagricultural societies in comparable places.
Cities require people more or less constantly.
As a constant flow of energy is required to supply and maintain the city, cities cannot
emerge prior to agricultural production. But once agriculture was achieved in human
ecology on whatever continent, cities were invented and implemented by necessity.
They are by no means comparable with any example or archetype in nature; even
agriculture can be considered an optimization and enhancement of what can be found
under a-hemerobic natural conditions. In terms of biology, life in cities must be beneficial
to their human inhabitants despite clear disadvantages, such as exposure to high-risk
infectious diseases and the intermittent shortage of nutrients. The main benefits are: 1)
access to informational processes that accelerate themselves and produce advantages in
terms of cultural achievements that allow the intensified use and exploitation of natural
goods, including other humans; 2) easier access to sexual partners.
206 These are best outlined and systematized in Lance H. Gunderson and C.S. Holling (eds.), Panarchy:
Understanding Transformations and Human and Natural Systems. (Washington, Covelo, London: Island
Press, 2002).
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