The world's population is expected to grow by another 2.3 billion, from 6.8 billion in 2009 to 9.1 billion in 2050.
Human consumption of renewable resources is already overshooting Earth's capacity to provide. Resources are becoming scarcer and the number of hungry people increasing year by year.
Reversing population growth is one of the measures needed to ensure environmental survival. It can be done by voluntary and peaceful means, given a political and individual will to act without delay.
Politically, governments can give urgent attention and increased resources to providing access to contraception and education to the estimated 200 million women worldwide who need and want it.
Individually, couples can decide to have smaller families, for example to Stop at Two children to make a difference to population growth.