The supply of economically usable natural resources is always only a small fraction of the overall supply of natural resources provided by nature. With the exception of natural gas, even now, after more than two centuries of rapid economic progress, the total of the supply of minerals mined by man each year amounts to substantially less than 25 cubic miles. This is a rate that could be sustained for the next 100 million years before it amounted to something approaching 1 percent of the supply represented by the earth. (These estimates follow from such facts as that the total annual global production of oil, iron, coal, and aluminum can be respectively fitted into spaces of 1.15, 0.14, 0.5, and 0.04 cubic miles, based on the number of units produced and the quantity that fits into one cubic meter. Natural gas production amounts to more than 600 cubic miles, but reduces to 1.1 cubic miles when liquefied.) Along the same lines, the entire supply of energy produced by the human race in a year is still far less than that generated by a single hurricane.
In view of such facts, it should not be surprising that the supply of economically usable natural resources is not something that is fixed and given and that man's economic activities deplete. To the contrary, it is not only a very small fraction of the supply of natural resources provided by nature but a fraction that is capable of substantial enlargement for a considerable time to come. Mining operations could be carried on at 100 times their present scale for a million years and still claim less than 1 percent of the earth.
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[UPDATE:] Here's an example of foolish sustainability whining.
And here's the refutation.