But why does it need to be reversed?
We are at the same time experiencing all the challenges and consequences of depleting the planet of resources, a warming climate and shortages everywhere. Why can less people in a natural way not be part of the solution?
You’ll need to kill people off at say 70. Healthcare meds increase dramatically when you get older and older, and that means more people needed to care. When the worker:dependence ratio increases you end up with people emigrating or care reducing.