Planetary physics can only provide a hard budget constraint if we are doomed to never leaving 'spaceship earth'. But if that is the case, Humanity is doomed in any case. If even a small number of people can leave this doomed planet so as to survive for another ten billion years then Cost Benefit analysis may yield a perverse result- viz. that non-renewable resources should be used up in an effort to get at least some of us of this planet. This is because the expected utility of the descendants of those who escape earth outweigh that of the earth-bound perishing for lack of air.

The other point is that genetic modification to permit our descendants to live in toxic environments may increase our inclusive fitness in the Universe.



There was a time when philosophers thought they could find a 'just price' or 'natural price' for various things. This was foolish. Equally, this sort of speculation is worthless. It is merely a type of virtue signalling which can be high jacked by rent seeking vested interest groups.



If you raise the price of carbon in a jurisdiction, then- ceteris paribus- carbon intensive processes migrate to another jurisdiction. This may be affordable if a particular jurisdiction is specializing in some high value added, 'green', industry. But such jurisdictions are likely to be small- so this is more like Tiebout sorting than the answer to a global problem. Of course, one can dream of a world government or a world where the leaders of nation-states are all angels who readily agree to cooperate in a wholly altruistic way. But, if one is content to dream, why not dream of a Universe filled with human colonists on distant planets?