I hate to be debbie downer here but I just don’t remotely see the kind of “doing less” strategy you propose as possible. You’re asking people to accept certain global economic collapse with absolutely horrific consequences that will be much more rapid and probably even more severe than those that may (and I stress may) occur from global warming. People simply won’t sign up for that in the developed world. They’ll find ways to deal with the heat or cold, flooding etc. long before they accept the doing less approach.