What we do on the climate file is like arranging the proverbial deck chairs on the Titanic. What we do with population control is the only relevant discussion on what we can do for the planet environmentally.  Humans will always seek to maximize their comfort zone at the expense of the commons. If you doubt this watch as the rest of the world, all (future) 10 billion of us,  strives to gain first world standards of living. It won't be pretty. Fewer humans equals more sustainability.