Michael Lind offers an optimistic assessment of the prospects for sustaining a world population of 9 billion.

As affluence grows, the amount of energy and raw materials “consumed” by machinery will escalate even more rapidly than human consumption. But this need not mean an end to the machine age. If manufacturing processes were to imitate the recycling that takes place in the biosphere, then most machine materials might be recycled to make new machines, rather than thrown away. And long before all fossil fuels were exhausted, their rising prices would compel industrial society not only to become more energy efficient but also to find alternative energy sources sufficient for the demands of an advanced technological civilisation – nuclear fission, nuclear fusion, solar energy, chemical photosynthesis, geothermal, biomass or some yet unknown source of energy.

Thanks to Tyler Cowen for the pointer.

For Discussion. If the world has 9 billion people in fifty years, what proportion do you think will achieve an income in today’s terms of $15,000 a year for a family of four?