Surely we need to solve this on the demand side; just turning off the supply seems a reckless way to transition the economy.
Both. Make it politically expedient, economically acceptable and make law. We do it all the time.
Give a people’s assembly the best available evidence. It could be credible (and therefore politically unpopular to dismiss it’s recommendations).
George Mombiot illustrated why we should try: Scientific reality is fixed. Political reality can feel fixed, but of course it isn’t.