> Except to do that, we have to end almost all transportation, reduce electricity usage substantially, stop using all concrete, stop flying airplanes, stop eating beef, stop using petrochemical fertilizers, etc. It is not an exaggeration to say that billions of people would die within 12 months.

I think there is a lot possible still. People would not die from smaller cars, less travelling, and smaller houses. Until the 1960s, people almost never took an airplane. Airlines sold the idea that 2 to 3 long distance vacations per year are necessary for mental health.