Earlier quoted context omitted.
Probably just family planning. Nobody needs to die to save the earth, well, not execution at least
Family planning how? Who will decide who can have children and who can't? Governments? A global one child policy? That's insane
Without a steady flow of migration from the undeveloped world to the developed world, the population of the native developed world would greatly decline in the coming decades.
There are none amongst the countries breeding at the rate of replacement [0].
We've seen that when a populace has better access to medicine, improving life expectancy and especially reducing child mortality rates, gains access to contraception & abortion, becomes better educated and less religious leading to becoming more well off and having their basic needs met as defined by Maslow, that they trend towards having less and less children.
Even migrants from the undeveloped world to the developed world have shown to have gradually less children as generations go by.
So the theory would be that we could bring down the world's population over time by simply making the above abundantly more accessible to those who are currently fueling the population explosion.
[0] https://en.wikipedia.org/wiki/List_of_sovereign_states_and_d...