Not OP but:

• population control (is hard but) can be done in a way that in 20-30 years starts having effect. Genocide is not the only way to reduce population?
• reducing the consumption of individuals does not amount necessarily to starvation and poverty either. Right now we produce too much and too poorly. Reducing consumption might mean less conspicuous consumption from the top 50% of the population but also less “things” that last more.

In both these examples unfortunately the main obstacle is economic.