The philosophical background to this idea, I presented on Thursday on 'living in a holarchy*', with a 'two way contract'.
The basic argument is the following:
Smaller scale structures (e.g. individuals, nations) need to take account the correct-function of larger structures (e.g. nations, earth system) in order to have a suitable habitat to live in.
Larger scale structures (earth system, nations) need to take account of the survival conditions of smaller scale structures (nations, individuals) in order to exist politically.
I think the 'conventional' current of green thinking tends to only see one way of the contract: the need for smaller scale agents to take account of the whole, in order to have a habitat worth living in. But there is also, in my way of thinking a second direction, the need for the larger scale structures to take account of the survival needs and desires of smaller scale agents in order to /exist politically/.
In this context, I think it may be well be worthwhile to focus on a) proper global taxation of carbon based fuels, especially coal; b) new energy supplies.
Regarding (b), the cost of decarbonising our energy supplies (and similarly making each house energy efficient) can be considered positive in an economic crisis, because of the demand stimulation. For the UK, final energy consumption of 240GW at about £2bn/GW (e.g. for uk wind/ccs/nuclear/imported concentrated solar with accelerated learning) makes investment required about £440bn, or about £22bn per year for 20 years. This is less than military expenditure of c.£30bn/year; and current total capital formation (investment) £64bn/year. The investment to will pay back in reduced oil and gas bills in the future. Also having sufficient energy supplies is a crucial part of being human. Arguments over fairness may be difficult when confronted with real human desires: energy is freedom and power. How do you make it worth people's while to reduce emissions? Decarbonising the energy supply also de-links economic growth with emissions, and this is essential.
I do agree that per-capita is a good rule of thumb in determining an apportionment of our relative impacts on the natural world.
I think equality may suffer from an 'equality of what' problem. For example, you could say by contrast that every human should have a right to a house warmed to a certain level, and energy needs would differ. Work by Richard Starkey has indicated the lack of philosophical support for equal per-capita entitlements, despite it's usefulness.
We also need to think more in terms of management and prices than emissions quantities, because creating rights to quantities will lead to 'rent-seeking behaviour'. Institutional arrangements (e.g a world carbon bank) may be better than trying to assign per capita emissions targets to individual nations and people. If you create more property, there will be a fight to enclose it. We need to move from emitting CO2 from being something valuable to fight over to something not valuable that we need to get away from. Better to instead tax carbon heavily, and provide guarantees for investment in alternative energy sources.
* The word Holarchy comes from Arthur Koestler. meaning "a hierarchy of holons — where a holon is both a part and a whole". See http://en.wikipedia.org/wiki/Holarchy
* Compare 'Panarchy'
* I'm indebted to Cormac Cullinan, who either provoked my interest in this concept or was thinking along the similar lines independently http://www.earthjuris.org/viewpointdocuments/Wild%20Law-Cullinan.pdf