Civil Engineering Reference
In-Depth Information
creates excessive waste. In theory, construction waste could potentially be reduced
to zero if the materials thrown away by one contractor could be used by another,
but this would require a process of putting the two together. As it is, contractors
tend to throw away valuable materials. Anecdotal evidence would suggest that as
much as £10 million could be saved each year by the larger contractors.
Maintaining the stock of natural capital is an essential prerequisite for
understanding and managing sustainable development. And according to
economists, there are two different approaches to achieving this goal. As outlined in
Chapter 9,
the basic premise of neoclassical economic analysis is that, left to its own
devices, the market mechanism will provide the necessary incentives to encourage
technological solutions to resource problems. In short, technological innovation
should provide substitutes for any 'shortages' in the environment. As a result,
the economy could grow forever. As Robert Solow (1974: 11), a Nobel laureate
economist, wrote more than 30 years ago: 'It is very easy to substitute other factors
for natural resources...The world can, in effect, get along without natural resources.'
An old phrase used to highlight the supremacy of the economic system was that
the economy would 'grow around' particular shortages such as resource problems.
Technology would invent an easy way out! This traditional technocentric view is
based on the
constant capital approach
, in which any decreases in natural resources
are substituted by increases in man-made assets.
Environmental economists present things differently. According to their analysis,
the economy and the environment are inextricably integrated. The ecosystem and
the economic system are viewed as complements rather than substitutes. In fact,
most environmental economists proceed from the mass balance model to argue that
the economy is a subsystem constrained by the ecosystem, as it depends on the latter
as a source of raw materials inputs and a sink for waste outputs. This ecocentric
view adopts the
natural capital approach
, which is based on the premise that it is
impossible to substitute natural capital with physical capital. According to Lovins
et al. (1999: 158), advocates of this type of approach, 'production is increasingly
constrained by fish rather than by boats and nets, by forests rather than by chain
saws, by fertile topsoil rather than by ploughs'. In other words, the material factors
comprising the ecosystem are unique and cannot be substituted at any price.
Empty World Versus Full World
To draw a distinction between these contrasting approaches, it is common for
environmental economists to present two models. One, an open system, which we
alluded to in
Figure 9.1
when we portrayed resources flowing in a linear fashion,
that pays no respect to the limits imposed by the environment. And the second, a
more constrained closed system, in which the environment physically contains and
sustains the economy. Some economists refer to the traditional view of the open
system as an 'empty world' model to contrast with the 'full world' model that is the
modern closed system.
Figure 11.3
is another way of illustrating the empty world model - the economic
subsystem is small relative to the size of the ecosystem. It depicts the past, when the
world was empty of people and man-made capital but full of natural capital.
