People and Planet: It has become taboo over recent years, but population, not consumption, really is the key to managing our use of the world’s resources, says John Feeney, Only since 1800, in the last 0.01 per cent of the history of Homo sapiens, has the human population shot into the billions. Now at nearly 6.7 billion, with 9 billion looming 40 years away, few environmentalists seem to care. Yet the population-environment link is clear. Our environmental impact, as gauged by total resource …