Fair National Greenhouse Gas Reduction Targets Under Multiple Equity Perspectives - A Synthesis Framework

Equity is one of the key principles underpinning the global climate regime and is all the more essential given the heterogenous, self-differentiated nature of the Paris Agreement. The scientific community has proposed several effort-sharing schemes to operationalise equity – reflecting not only the multi-faceted nature of the problem but also a long history of disagreement that continues to date. We outline a synthesis framework that draws on existing estimates in the literature to develop a “fair share range” for each country within which we identify a common position, which, when applied to the ranges of all countries, results in the collective achievement of the desired temperature goal. A series of methodological choices regarding the treatment of the underlying literature and translation into a temperature equivalence are tested. We demonstrate the consistency of this framework (across different methodological choices) with the principle of “Common but Differentiated Responsibilities” – members of the OECD have the most stringent allocations, while only a few African and Asian countries (including India) have emission allocations that are above their 2010 emission levels. A few OECD members, including the European Union and Great Britain, have emission allocations in 2030 that are either close to, or less than zero. Consistency with their fair share of mitigation will require them to provide appropriate levels of international finance and support to facilitate emission reductions in developing countries. These conclusions are robust to various methodological choices.