Policy is not going to fix this. Neither are politicians. We're trapped in an economic model which demands infinite growth. A system built principally on hydrocarbon energy. Modest improvements can be made to improve efficiencies (see Jevon's paradox), but we're in a treadmill to hell. You can't grow GDP without consuming more energy. We stop growing, the system will collapse. And you're never going to have a politician get elected on a platform of conservation. "You know all that wasteful consumption we've enjoyed since winning the second world war, you're going to have to do with less"
Like mold in a petri dish, the human population will collapse ultimately into decentralized anarchist societies who trade among one another. Assuming we stop the 400+ reactors from going into meltdown, the majority of the population will return to farming.
We're not going to Mars anytime soon. You people can't live without AC or even know how to grow a fucking tomato plant. Sadly, most of this community will die.