[Mistwraith]

Medical scientific progress means life expectancy rises creating a population issue.
Required - less births to cope with the numbers, not war, extermination or any other factor that requires life to be exintinguished.

People tended to have huge families because surviving childhood was unlikely.
Western world on the most part doesnt do this any more.
Re-education of the whole world to this principle would slow this growth immensely.

A cull thro war upsets - look at the reactions to recent small wars to see that.