Interpreting climate performance indices: implications for equitable and effective policy

Climate performance indices play a crucial role in evaluating countries’ efforts and advancing global environmental governance. This study critically examines disparities among prominent climate performance indices, including the Environmental Performance Index (EPI), Climate Change Performance Index (CCPI), and Climate Action Tracker (CAT). Our analysis reveals significant divergences in country rankings, particularly between ‘developed’ and ‘least developed’ nations, underscoring how subjective methodological choices impact indices’ results and their interpretation. We develop an analytic tool, called EPI-equity, to demonstrate how integrating equity principles can substantially alter performance assessments. We furthermore propose a novel conceptual framework to classify indices based on the choice of methodological framework and embedded normative choices, highlighting how these can shape the interpretation of performance. These results allow the contextualization of outcomes of climate performance indices and the degree to which they concur with one another. Thus, this framework helps translate methodological choices into a conceptual understanding of what an index truly measures. We propose that explicitly articulating the normative choices embodied by performance indices can enhance transparency, guide developers in aligning methodological choices with intended interpretations, and equip users with a clearer understanding of the results. Our analysis highlights the importance of employing multiple indices that encompass a range of normative choices for a comprehensive evaluation of countries’ climate performance. This adaptable framework provides a structured approach to guide the selection of indices spanning a broad spectrum of viewpoints, and, thereby, mitigates the likelihood of conflicts arising from fragmented worldviews on complex socio-environmental issues. Climate performance indices can yield contradictory assessments due to differing underlying approach of normative choices. No single index can capture all dimensions of climate performance. Policymakers should use multiple indices to guide decision-making, ensuring a comprehensive evaluation of national climate performance. Policymakers benefit when index developers explicitly articulate both the methodological framework and normative preferences embedded in their normative frameworks. This transparency helps mitigate conflicts such as those seen between the CCPI and EPI developers and the Australian and Indian governments, respectively.