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 the disparities among prominent climate performance indices, including the Environmental Performance Index (EPI), the Climate Change Performance Index (CCPI), and the 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 the results and interpretation of indices. 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 enable the contextualization of the outcomes of climate performance indices and the degree to which they align 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 embedded in performance indices can enhance transparency, guide developers in aligning methodological choices with intended interpretations, and provide 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