139
(as they have done), the results of the study are
obvious--they are determined by conditions assumed at
the start and follow as surely as those of any equation
must. Yet, given finite limits, exponential rates of
growth cannot continue.
The results of the Club of Rome and the Barnett
and Morse studies (however they differ) essentially
arise out of the role assigned to technology. If
exponential growth in production yielded exponential
rates of growth in the demand for resources, benefits
of technology would have to accrue at a rate greater
than or equal to the rate of increase in resource
demand; either that or a limit to further growth
eventually must be reached. For example, chromium, a
metal with one of the longest lifetimes in terms of
resource adequacy, could be expected to last another
95 years, given current rates of increase in demand
and currently known reserves. With a fivefold increase
in reserves, resulting from new discovery and technical
change, demands could be met for 154 years. The same
projections for iron are 93 years for currently known
reserves and 173 years if reserves are increased
fivefold. The projections for copper are 21 years
18
and 48 years, respectively.
18
Meadows et al., Limits to Growth, pp. 56 62.