Allocating constrained global carbon budgets: interregional and intergenerational equity for a sustainable world

Abstract

The feasibility of an effective international response to anticipated climate change is dependent on the recognition of the present and historical inequities between developing and industrialized countries. Developing countries should be enabled and supported to continue their development towards higher standards of living in a fashion that is consistent with the sustainability of the global biosphere. This paper evaluates long-term climate strategies by which the burden of mitigating climate change by controlling CO2-emissions is shared equitably. Here we use as a possible criterion of equity, that every human being, past or future, is allowed to emit the same carbon quotum on an annual basis. Using such an interpretation of interregional and intergenerational equity we calculate the 'emission debts' and future regional per capita emission quota for the world-regions. The results show that past industrialisation has coincided with a large relative contribution of the rich regions to the rise in CO2-concentration, an estimated 40% for the EC and North America, which have built up an emission debt of 36 GtC and 75 GtC resp. using recent World Bank projections of population growth. The developing countries, however, have built up an emission credit of 24 GtC. These regional emission debts and credits increase the future per capita budget for the developing regions till 0.2 - 0.8 ton C/cap yearly, whereas North America and the EC end up with negative future carbon budgets. Even if the IPCC Business-as-Usual scenario is considered as reference, the future emission quota of most industrialized countries are lower than their present per capita emissions.