The so-called scientists who are united in a grand consensus about taxing carbon to save the planet seem to be limited to agreeing on partial taxes that might prevent the future disaster that they claim. Carbon reductions would have to be massive everywhere to avoid disaster. The ugly facts are that those in power [EU members mostly] want to exclude China, India and most emerging nations, tax the US, and also ignore the salient fact that their own EU members have not cut carbon emission standards according to agreed norms. The matter is complex [see WIKI Carbon Tax https://en.wikipedia.org/wiki/Carbon_tax].
Let us assume that carbon emissions must be reduced to save the planet. The end of civilization is in sight! What can we do?
So, let us jump ahead of this mess and ask: could the planet inhabitants stop burning fossil fuels to an extent that CO2 levels would be reduced to meet these goals? Given that the USSR, India, US and others in Africa and Asia are reluctant or refuse to make such cuts then what happens to the world?
Given the huge costs of avoiding energy generation by coal and petroleum components the answer is NO! It will not happen. Many nations would collapse economically if they were forced to use only alternative energy sources.
So, given our histories of our planet just what would happen?
Well, war for sure as survival then clearly depends on lowering carbon emissions at all costs everywhere and that means many nations would not be permitted to manufacture food and other essentials with energy. This assumed state then tends to predict that collations of countries might form new alliances where they avoid as much carbon oxidation as possible and prevent others from using any at all. The powerful would use as much alternative energy as possible even at high energy costs of solar and wind mechanisms just to survive. This is undoubtedly the predictive teaching we get from a study of the history of the world. The outcome would mean war, mass starvation, malnutrition, migration away from cold climates and much more.
 Prevent the less powerful nations from using carbon-based energy systems on pain of war.
 Demand a drastic reduction in the human population.
 Secure all locations on the planet where energy is cheap and not carbon based to produce food, arms and goods.
 Employ the Survival of the Fittest methods as usual.