> reduce the global population by 3/4 with growth control.

Given that most of the world's population is under 30 years old[0], even if you could get every country in the world to simultaneously ban child birth tomorrow, the world population wouldn't even halve by 2070. (You also need to take into account global life expectancy changes that far into the future[1]).

[0] https://socialnomics.net/2010/04/13/over-50-of-the-worlds-po...

[1] https://www.statista.com/statistics/673420/projected-global-...