I was born in 1955. There were 3.5 billion people.
Now we have 8 billion.
I think we have a problem. Just like smart folk have been saying since, oh, a long time.
Come back Thomas Malthus, all is forgiven.
The only country with the, um, balls, to tackle the problem has been China. And it's not gone especially well there.
It appears population growth slows, and even reverses, as countries become rich. The currently population boom is in Africa, eg Nigeria (HDI 0.51).
There is a small correlation between low HDI and high population growth, and the reverse, but it's weak. Religion and economic factors probably have significant effect.
Trying to move to Mars is not going to help, despite Elon's best efforts (though we must commend him for attempting to make a "backup" civilisation).
So what to do?
* We need to solve the carbon problem before large areas with large populations go underwater or become untenable (eg Bangladesh), or we are going to get even more chaos
* we need to work on empowering women in poor countries to control their own birth rates (education!)
* we need effective and cheap contraception to be readily available (for men and women)
* we need better pre and post natal care to increase the survival rate and health of children (and thus reduce the need for "spares")
* we need better old age care to reduce the desire for "children to look after us in our old age"
* we need to get fast breeding religions (cough, Catholicism) to stop it, just stop it (education)
* the massive numbers of single parents (mainly women) is contributing to poor breeding practices (arguable)
So which of these do you want to contribute to?
(Disclaimer - I have 2 children. On the other hand, my [only] sister has none)