1. Impose restrictions on the number of kids.
2. Focus on lowering the impact of the population (no huge mansions for one douchebag when people are living cramped up like sardines), eliminating personal overindulgence.
3. Colonizing new areas. Underground colonies, underwater colonies, off planet colonization.
In short, lowering or stopping population growth, managing the existing population better so it has fewer negative effects and finding places where to shift the population.
2. Focus on lowering the impact of the population (no huge mansions for one douchebag when people are living cramped up like sardines), eliminating personal overindulgence.
3. Colonizing new areas. Underground colonies, underwater colonies, off planet colonization.
In short, lowering or stopping population growth, managing the existing population better so it has fewer negative effects and finding places where to shift the population.