A wild card in the struggle to save civilization is one key idea of Buckminster Fuller's. Bucky said lots, but this probably is his most solid, and maybe useful, idea.
He said it's invisible, because it involves a kind of knowledge most of us don't have or pay understand.
Modern alloys have many times the tensile strength of rocks, lumber, or concrete -- conventional building materials -- and greater tensile strength than nineteenth century steel. Of course, conventional buildings are made by piling things on top of other things -- compressively -- and materials' compressive strengths are relatively pitiful.
Also, Fuller's geometry, which you can see in his invention, the geodesic dome, is tensile -- it hangs together. Build our structures using Fuller's tensile geometry and incredibly strong modern materials, and it only takes a tiny fraction of the material conventional techniques would. Those domes are hanging from themselves, and could cover counties without any pillars.
The combination of modern materials and a kind of building which hangs instead of stacks might be economical enough to make us the planet of billionaires Fuller claimed we are, "entirely unaware of our good fortune."
In the twenties, Fuller analyzed a model modern house, proposed by the American Institute of Architects, realizing that all of the lumber, plumbing, concrete, wires, appliances, etc. would weigh 150 tons. He designed his Dymaxion House to provide the same area and functions for three tons. The Dymaxion House would have been mass-produced, so there would have been time savings, as well.
After World War II, he built two prototype Dymaxion Houses, which operated as proposed, and weighed...three tons each.
Objections are that these structures would be unconventional and startling, compete with existing industries, aren't the kind of things individuals can do by themselves (industrial production versus craft), requiring cooperation, and the possibility that there would be hidden infrastructure belying apparent economies. But these are just questions. It would be nice if people caught on to possibilities like Buckminster Fuller's in sufficient number to start having a conversation.
The stakes are too high not to.