The vertical policy harmonization indices: assessing the gap between climate mitigation pledges and policies

The effectiveness of the Paris Agreement in achieving its global temperature goal relies on countries adopting ambitious mitigation targets and introducing corresponding measures. But do countries adopt such corresponding climate policies? This paper introduces two Vertical Policy Harmonization Indices, which quantify the gap between a country’s nationally determined contribution (NDC) mitigation pledge and its national mitigation policies. These indices incorporate three dimensions of climate policymaking: emission reduction targets, the sectors covered by those targets, and the policy instruments introduced to reduce emissions. By focusing on policy instruments and mixes, we adopt a novel public policy approach for the harmonization assessment. While the Target Index compares the level and scope of reduction targets in the NDCs and national policies of 105 countries, covering approximately 91% of global greenhouse gas (GHG) emissions, the Policy Effort Index also incorporates a comprehensive evaluation of the policy mix of selected countries. With the Policy Effort Index, we investigate 37 countries, covering over 70% of global GHG emissions. The indices show that three-quarters of the 105 countries have so far failed to translate their NDC targets into national policy. The remaining quarter has harmonized or even more ambitious national policies. Furthermore, countries show the most complete national policy mix in their most GHG-intensive sector, usually the energy sector. These insights demonstrate the indices’ potential for enabling future research explaining the deviations between countries’ domestic actions and their international pledges and evaluating the effectiveness of the progression mechanism as countries update their NDCs.Twenty-six of the 105 countries have national policies with GHG reduction targets either in line with or more ambitious than their NDC target.Seventy-nine countries (accounting for 50% of global emissions) have failed to translate their NDC target into a national policy.Countries tend to have their most balanced and intense policy mix in their largest emitting sector, which often is the energy sector.The coerciveness of policy instruments and the likelihood of their implementation remains low across sectors.EU membership, and development status appear to be indicative of the gap between climate mitigation pledges and policies.