Telling women to have fewer children will not cure overpopulation.

Reducing aid to poor nations will not cure overpopulation.

Making contraception more available in developing nations will not cure overpopulation.

The only thing that has proven effective in the (most urgent) fight against overpopulation is education and a higher standard of living.

This sounds easy, but increasing SOL and education has proven to be extremely difficult in these parts of the world. Religious indoctrination, corrupt warlords siphoning aid, war, famine, tribalism, etc. make it extremely difficult to change these societies, but we can't give up. Hopefully with Blockchain technology, we can use funds for intended purposes and out of the coffers of warlords and religious leaders. This is the only light I can (barely) see at the end of the tunnel.