Probably heavy taxation of consumption and lowering the average standard of living across the globe. Too bad it's a pipe dream, people will never vote for it and an dictator that tries to impose it will be overthrown.
I think the only thing that can save us short-term is technology. Inventing and implementing new gizmos is something we're actually good at. Long-term we're probably screwed anyway, because we'll eventually disturb the biological systems on the Earth too much (either via pollution, ocean acidification, killing biodiversity, soil depletion etc.), and they're way too immense and complex for us to fix. People forget that we're part of Earth's ecosystem, but if we disturb it too much we'll be reminded of it either via plagues (we got a taste of it already) and/or famines.
The only thing is whether any of it will be in a somewhat controlled, damage limiting fashion, or will it be just one stupid catastrophe after another.
I feel new gizmos are generally just more fuel onto the fire of consumerism, and will just speed up the process, not slow it.
The USA wastes a lot more resources to achieve similar standard of living to Europe. And even Europe is putting a lot of effort into policies that simultaneously improve their standard of living and reduce waste or pollution.
Saying that "standard of living" is synonymous with "amount of fossil fuels you burn" is standard climate change denier rhetoric.
People with efficient cars and well insulated homes have higher standards of living than those who don't.
It's not similar though. Americans live in way bigger homes and on way bigger plots of land. Streets are wider. Everything is less cramped in general. Also, US has possibly the best health care quality (note I'm not discussing health care _insurance_) in the world. They can also afford more consumer niceties (iPhones, nice cars, foreign vacations etc.). All that extra stuff and quality requires extra fossil fuels and minerals.
Water, Uranium, Gold, Copper, Sand?
Whatever it is, there's almost a certainly a way to use it more efficiently and therefore improve standards of living in Europe, and the rest of the world, at the same time.
And things that are mined in general (like metals). They won't run out but as we mine the easy deposits first, the amount of energy it costs to mine a given amount will be forever increasing. E.g., eventually it will cost more energy to mine the materials for a wind mill than the electricity it will generate in its lifetime.
The only pipe dream is to continue breaching the planet boundaries.
But severe limitations were imposed during wars on the population by the state, so they are in the realm of possibility (once we acknowledge the severity of the problem, which we are not doing, because of many reasons).
We should also add that the expansion of renewables energy create more jobs than the fossil fuel sector, therefore there is at least some hope of this limitations being not as severe as w think. It was calculated that, to be sustainable, the lifestyle should go back to the sixties, during which we lived fairly well but without a savage overconsumption as now.
No. The earth doesn’t need saving. The diversity of life needs saving. Planetary boundaries is the wrong goal.