From Jorg Friedrichs' The Future is Not What it Used to Be (p.3-4):

For the sake of the argument, assume that world economic output continues to grow by 3 percent per annum. This implies that global GDP will double within twenty-three years, and quadruple within forty-six years. It also implies that, a century from now and other things being equal resources consumed and pollutants emitted will have increased by a factor of more than sixteen. It is easy to see that such enormous growth would not be sustainable. The obvious objection is that resources consumed and pollutants emitted can be reduced by efficiency gains and other forms of technological progress. So let us assume, again for the sake of the argument, that resource intensity and thus pollution can be reduced by a fairly ambitious 50 percent. Even so, under the above scenario, a century from now the world economy would consume eight times as many resources and emit eight times as many pollutants as today.

To continue the thought experiment, let us demand that the world economy should grow for a century by 3 percent per annum, but without any increase of resource consumption and pollutant emissions. By how much would it be necessary to abate the resource and emission intensity of the world economy (resources consumed and pollutants emitted per unit of GDP)? The answer: by a staggering 94.8 percent. To reconcile a century of 3 percent growth with the more ambitious goal of reducing resource consumption and pollutant emissions, the abatement of resource and emissions intensity would have to be even more drastic.