If I could make one thing happen, it would be for the UN - or whatever the leading international organizational body (or bodies) of the time happen to be - to adopt targets for the human population on Earth. This is a fundamental stepping stone toward deciding what humans want humanity to look like. Without this and/or some other fundamental building blocks on which to construct a society, humanity resigns itself to a path guided as much by luck and fate as by forthought and planning. I suppose that I'd even be okay with such an organic evolution of our species if it were the concious will of the masses, but reflecting on our history, the masses lack time to consider this or any other alternative. Perhaps I should seek out books touting the merits of both positions and reflect more before coming to any sort of final or even temporary conclusion. Books I ought to read: The Three Body Problem, Sapiens: A Brief History of Humankind.