For a while it was talked about. But now, once again, overpopulation seems to have become a taboo topic. But with the populations of China, India and Indonesia all around the one billion mark, the time for such coyness is long past. China's one child policy is fine in its own way. But what is needed is population reduction. Despite what many people say food production is not the main problem resulting from too many people. The real problem is the utilisation of the world's finite resources - metals, fuels and so forth.
Ultimately unless mankind starts to control its population the world's resources will unable to sustain that population.
The time to start talking and debating and planning is NOW.