Replace existing economic and political systems with decentralized alternatives. Transparent, open, permissionless, provably fair. Everyone plays by the same rules.
We need to be able to encourage and incentivize specific solutions/industries, and tax those that are damaging to the planet. Problem solved, capitalism and democracy can be its own salvation. Control by the masses, not an elite.
I get that it seems like a pipe dream and would never work for some unspecific hand-wavey reason, but it is our last chance. We have the technology, there's no need to be defeatist about our situation just yet. All it takes is for a big enough mindshare to start exploring the possibilities.