First, defining equity as convergence to equal per capita shares or rights by all the parties involved assumes that equal capabilities will result. This is the same error that paleo-economists make when they define poverty in terms of relative income rather than using capability analysis to determine what that income can provide for sustenance. For example, a Siberian will likely need more energy than a South Sea Islander for equivalent capability to survive and thrive. Location may matter as much as population for a truly logical basis of equity.

Secondly, the GCI model is a perverse incentive to overpopulate a region for financial gain. Individuals may not make this cynical decision, but their totalitarian governments almost certainly will. Conversely, sparsely populated nations are penalized for their parsimony.

Taken together these flaws seem to make the GCI model inequitable and likely to fail should it be implemented.

A nagging concern in this is that it may also fail to affect climate in any useful way. It will take 100 years for the excess CO2 now in the atmosphere to breakdown and during that time the effects will accumulate. Natural climate variation seems also to be heading toward increased warmth though the relative contributions of GHGs are not yet understood. If we do C&C and the poorer southern societies still submerge there will be trouble.

It seems that we need more realistic models. It is the standard modelers dilemma - models of low dimensionality fail to describe systems but the measurement and calculation needed for more dimensions exceeds present capabilities. And it seems we need to be more cautious about how we spend our limited resources, to avoid risky expenses and save some for a hot, rainy day.

Though the GCI model seems simple it may be merely simplistic. The measurement problems mentioned above for useful model building will be many times more difficult for operation. Measurement and accounting on even a corporate scale are daunting tasks and hopeless at the national level as existing national budgetary machinations demonstrate. On a global scale where there are no existing regulation or enforcement mechanisms it seems impossible. Every regulated substance spawns a criminal organization to smuggle and exploit the regulations. To expect humans to cooperate with the spirit of such a system is fantasy. Nice theory, wrong species (paraphrasing E.O. Wilson in another context).

The world probably won't end if C&C is adopted but it is highly doubtful that the 'film will be like the novel'. It seems to be a breathtakingly bold gamble that essentially tosses human civilization into the air just to see how it will land. It may be better, but nothing in the GCI model offers insight into what that new world will be like.