(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

and 48 years, respectively.18


 18Meadows et al., Limits to Growth, pp. 56, 62.