ABSTRACT
Urban centres and urbanization (the increasing proportion of a population living in urban centres) do not enjoy good reputations from an ecological perspective and are often cited as drivers of unsustainable environmental change [1,2]. Certainly, the much increased pressures on the world’s natural resources and ecological systems over the last century or so has been accompanied by a very rapid growth in the world’s urban populationfrom 260 million in 1900 [3] to over 3.4 billion today [4]. The world’s population has urbanized rapidly, driven mainly in recent decades by the very large expansion in the world’s economy and by changes in its structure. Most new investment, economic value and employment have been in industry and service enterprises and most such enterprises have chosen to locate in urban areas. This helps in explaining why the ratio of rural : urban
dwellers changed from 7:1 in 1900 to around 1:1 today [5]. The rapid increase in urban population and urban production has been accompanied by an even more rapid increase in the use of fossil fuels (and hence in carbon dioxide emissions) and in most other mineral resources and in freshwater, fish and forestry products. Urbanization is also associated with increasing wealth (at least for a proportion of the growing urban population) and increasing per capita consumption levels. In many nations, urbanization has also been influenced by the locations chosen by multi-national corporations for their production and for the centres where they concentrate their management [6]. Thus, urbanization can be seen as one of the key drivers of high levels of resource use and waste generation that have serious ecological consequences locally (within and around urban centres), regionally (where resource and waste flows from urban centres shift to the wider region) and globally (for instance in regard to climate change and in the reduction in the ozone layer).
