I have not yet read the book, but I've been familiar with and supportive of the concept since Mayer Hillman among others floated it some years ago.

Here is a review and on the same page some very depressed and depressing discussion of the review.  I'll try to get the book soon -- though it seems very carbon intensive to order one from the UK :-(

from the review

Monbiot argues for a global carbon emissions cap allocated on a per capita basis. Since all of humanity shares the biosphere, which has only a limited absorptive and cleansing capacity and all humans are created equal, then each should have equal use of that capacity.

The implications of biospheric equity are so profound and so disturbing, that it is understandable why American environmentalists shy away from discussing the issue. Currently, global carbon emissions are about 7 billion tons, roughly, 1 ton per person. But the average American generates, directly and indirectly, some 10 tons per capita. Thus, to save the planet and cleanse our resource sins, Americans must go far beyond freezing greenhouse gas emissions. As a nation, we must reduce them by more than 90 percent, taking into account the sharp reductions in existing global emissions necessary to stabilize the world's climate.

justabout nothing that affluent nations have done in the last 400 years indicates that global equity is of the slightest interest to their populations or governments -- quite the reverse if anything, they have spent trillions of bux and millions of lives trying to stamp out any attempt at it.  so treating the planetary population as equally entitled to carbon credits is a just and fair solution with approx the political chances of a snowflake in a solar-heated greenhouse gas envelope -- failing some major social/cultural transformation.

The difference between theory and practise in practise ...