A scientific recommendation that 50% of the Earth's surface be protected wildlife areas by 2050, to avoid massive extinction.

If we want to protect more than desert and mountain species, protected lands will have to include a lot of places that could be used for agriculture, at least for 20 years till they are exhausted. To protect them, we need to keep human farmers away. That will be difficult, but keeping the birth rate down will make it a little easier.

In addition, protected areas may not serve their purpose if global heating makes them unviable habitats for some of the species that live in them. Curbing the human population will also make progress towards reducing global heating.