The other major alternative is diet from aquaculture, which has better fresh water and land use than vegetarianism.

What we need to do is make the externalities created by farming part of the food price, including the pollution they create. The artificial fertilizers, the fossil fuels, the energy costs, water pollution, eutrophication, the destruction of biodiversity and land usage. All of it need to be part of the price so that it incentivize a change in the dietary culture towards more sustainable production.

Getting people to change their culture is the hard part. Convincing people to eat less meat is like convincing a vegetarian to eat more molluscs. Almost impossible.