Page "The Limits to Growth" Paragraph 8

One key idea within the The Limits to Growth is the notion that if the rate of resource use is increasing, the amount of reserves cannot be calculated by simply taking the current known reserves and dividing by the current yearly usage, as is typically done to obtain a static index.

For example, in 1972, the amount of chromium reserves was 775 million metric tons, of which 1. 85 million metric tons were mined annually ( see exponential growth ).

The static index is, but the rate of chromium consumption was growing at annually ( Limits to Growth, pp 54 – 71 ).

If instead of assuming a constant rate of usage, the assumption of a constant rate of growth of annually is made, the resource will instead last