Green activists, free-market economists and religious fundamentalists may not seem to have much in common, but they are all agreed there can be no such thing as overpopulation...
Actually, the perennially unpopular Rev Thomas Malthus was closer to the truth when, at the end of the 18th century, he argued that population growth would finally overtake food production. Industrial farming was supposed to make famine impossible. But it turns out to have been heavily dependent on cheap oil, and with farmland being lost as a result of the switch to biofuels, limits on food production are re-emerging. Far more than fantastical schemes for renewable energy, we need to ensure that contraception and abortion are freely available everywhere. A world of fewer people would be far better placed to deal with climate change than the heavily overpopulated one we are heading for now.