8.3 Scale Limits, Sustainability Rules and Substitutability
8.3
Scale Limits, Sustainability Rules and Substitutability
What measures can we use
to assess whether economic development has reached the sustainable limits?
On this question
mainstream economists and ecological economists tend to disagree and have
developed what have been termed alternative “weak” and “strong” sustainability
criteria.
The weak sustainability
criteria held by neo-classical economists believes that future generations will
be richer because of economic growth and that all that is required is that the
“bequest package” of all kinds of capital from one generation to the next is
not, in aggregate, smaller. In this point of view it is perfectly justifiable
to run down “natural capital” resources as long as adequate substitute human
made capital resources are built up instead. To these economists what matters
is the overall monetary value of the bequest package rather than what the
portfolio of real assets underlying the financial package actually consists of.
Future generations may not have all we have access to – but will have adequate
or better substitutes.
By contrast strong
sustainability rules suggest that minimum amounts of different types of capital
(economic, ecological, social) should be independently maintained, in real
physical and biological terms. Ecological economists insist that there are some
natural resources which are essential inputs in economic production,
consumption and welfare that cannot be substituted for physical and human
capital, some environmental components are unique and some critical
environmental processes may be irreversible – e.g. climate regulation. This
gives rise to strong sustainability rules:
For
a renewable resource – soil, water, forests, fish – the
sustainable rate of use is not greater than the rate of regeneration of the
resource (e.g. fish – not sustainable if more fish are caught than the rate of
growth of the remaining fish population)
For
a non renewable resource – fossil fuels, high grade mineral
ores, fossil aquifers – the sustainable rate of use is not greater than the
rate at which a renewable resource is substituted for it (e.g. an oil deposit can
only be used at a rate at which some is set aside and invested in
wind/solar/biomass so that when the oil is gone an equivalent energy stream is
available to replace it).
For
a pollutant -
the sustainable rate of emission is no greater than the rate at which the
pollutant can be recycled, absorbed or rendered harmless in a sink. (e.g.
sewerage can be put in a water system no faster than bacteria and other
organisms can absorb its nutrients without the aquatic ecosystem being
overwhelmed and destabilised).