A four-step process for formulating and evaluating legal commitments under the Paris Agreement

Abstract

This paper describes a four-step process to guide national governments in formulating and explaining greenhouse gas (GHG) emissions reduction targets in their Nationally Determined Contributions (NDCs) under the Paris Agreement. The NDC pledges in aggregate are intended to achieve the Paris Agreement's warming limit goal to hold the increase in the global temperature to well below 2°C and to pursue efforts to limit the temperature increase to 1. 5°C. Nations also agreed in the Paris Agreement that their mitigation pledges would be based on equity and common but differentiated responsibilities and respective capabilities, in the light of different national circumstances. This paper describes the four steps that are required tofulfil these commitments, and to ensure that the NDCs are sufficiently transparent to allow the Paris Agreement's 'stocktake' process and 'transparency mechanism' to achieve their goal of increasing the NDCs' ambition and fairness. The four steps are necessary to implement the legal obligations of the parties under the UNFCCC and the Paris Agreement. Thesefour steps are: (1) Select a global warming limit to be achieved by the GHG emissions reduction target; (2) Identify a global carbon budget consistent with achieving the global warming limit at an acceptable probability; (3) Determine the national fair share of the global carbon budget based upon equity and common but differentiated responsibilities and respective capabilities; and, (4) Specify the annual rate of national GHG emissions reductions on the pathway to net zero emissions.