We could design and plan a zero emissions civilization with a circular economy with today’s technology. Practically it’s absolutely impossible because it would be near 100% wealth redistribution.
Urban density would need to be increased, every home would need to be well insulated, homes would need to become smaller, home / work would need to be smaller meaning companies and living communities would have to be planned and forced to move, many small towns completely abandoned. Public transport, no more meat production, cars replaced with bicycles, smaller cars or 1 or 2 person robo taxies. Passenger airplanes would have to fly slower to save fuel. Massive amount of trains build. Hundreds of thousands of industrial processes would have to be redesigned, factories torn down and new ones build, patents would have to be abolished, no more large scale warships or bombers or jets, industrial production would need to be localized and moved from overseas to multiple smaller producers all around the world. Any of this goes far beyond regulations, and not even regulations are politically possible.