Probably the sun and small scale fusion for at least the next thousand years or so. Eventually other stars/large scale fusion/some type of energy production we haven't discovered yet.
>and space
There is enormous amounts of room left on earth. Everyone on earth could have an acre of land to themselves with 10x the current population, and that completely ignores multi-level construction (either above or below the surface). But long term there is a lot of space outside of earth.
> There is enormous amounts of room left on earth.
Bonkers - if we are to believe the environmental lobby (and I generally do), we are already destroying much of the biosphere. You can't have it both ways! Either things get worse for everyone, or humanity starts to control itself.
>Either things get worse for everyone, or humanity starts to control itself.
Controlling itself doesn't have to mean population control. It just has to mean taking care of our environment in a sustainable way. The number of people we have been able to support in a sustainable way has increased by several orders of magnitude over the past tens of thousands of years and I don't see a compelling reason that trend needs to stop. Climate change isn't tied to population, it's tied to greenhouse gas emissions. We already have the technology demonstrating that we don't need to emit greenhouse gasses.
> Climate change isn't tied to population, it's tied to greenhouse gas emissions.
Extinction of other species is also tied to deforestation, mining, pollution (chemical, light and noise) as well as hunting and accidents. All of that only increases as our population grows.
To what end, though? What is the point in endless expansion? I think at this point we're just expanding out of some basic evolutionary urge, but like other such urges that have outlived their usefulness, I feel like we need to revisit this one.
