Worstall's "rebuttal" makes some interesting points but also shows that he is blind to the role that energy plays in the availability of materials (i.e. in the conversion of "resources" into "reserves"). Coming from a conventional economist that is no surprise. Technology can only take us so far in overcoming the problem of diminishing resource "quality". There are energy barriers which cannot be surmounted and that is why future declining energy availability is so critical. You will have to consult a biophysical economist such as Hall to get a more realistic opinion.