Geography Reference
In-Depth Information
input-output approach that tries to understand what amounts to the metabolism of
urban places. For example, every urban area and the buildings, population, and
functions within them, including the transport that connects them, require a series
of inputs—such as water, energy etc., in addition to food and a range of created
products—which are consumed in the city. They usually produce not only useful
products through manufacturing or services, but also unwanted waste and noxious
pollutants as outputs, some of which create regional and global damage not simply
local urban ones. As cities got bigger and more technological devices were cre-
ated after the Industrial Revolution, the addition of the inputs and disposal of these
waste outputs were largely solved by separate, yet creative engineering solutions
for each product, following what amounts to an largely linear approach. To take
one example, energy in the form of coal was brought into cities in the Industrial
Revolution, burned for heating and for powering various plants, and the waste was
dumped, while the noxious pollutants produced from the burning of coal were ini-
tially ignored because it was an externality to the linear raw material-energy output
solution. But this type of approach ignores the consequences of the linearity de-
scribed earlier, such as the London smogs, or the current high air pollution levels in
Beijing and other major Chinese cities of today. In similar fashion, first gas and later
electricity derived from coal were used for power and lighting etc., but given the
difficulty at the time of transmitting them over long distances the generating plants
had to be located close to the cities.
From the early twentieth century the technical innovations in creating long-dis-
tance electrical transmission lines meant that cities could be supplied from large-
scale generating plants located near raw material energy sites, or in places that used
imported fuel. The next century saw an explosion in the development of bigger
generating plants and long transmissions lines spreading over hundreds of miles,
controlled by complex interlocking electronic systems. In addition, greater amounts
of oil and natural gas as well as other sources of energy were used, all with their
own supply sources and processing and transport systems. By using a more compre-
hensive input-output approach the effect of the materials brought in and out of cities
is not only related to their immediate effect in the cities, where they are used and
created, but to the whole supply and output chain. For example, this makes it pos-
sible to consider all the environmental and health effects of mining and transporting
the coal, as well as the local, regional and world effects created by its processing
and the final waste products. The result is to reduce the understanding of all these
issues to two fundamental questions in sustainability: What are the current sizes and
sources of inputs and outputs? What are the problems that affect policies designed
to change the inputs and outputs so they are less wasteful of resources and create
less harm to the environment?
5.4.1
Eco-Cycles
An important approach to the input-output approach to sustainability can be seen
in the eco-cycle approach. This describes situations in which circular and more ho-
