Research suggests that the single biggest thing anyone can do to reduce their impact on the environment, and the climate, is to choose to have one less child. But that simple solution is complicated by thorny economic, ethical, social and political issues.
This year, the human population on Earth is expected to reach eight billion. To mark the occasion, BBC Future takes a look at one of the most controversial issues of our time.
“Humankind is using up the biophysical basis of its own existence." That's the bottom line of this Earth Overshoot Day conversation with William Rees, the father of ecological footprint analysis.
