Varied drivers for reducing CO2 emissions in countries with legislated carbon neutrality targets: a Kaya identity clustering analysis

Abstract Since the Paris Agreement, an increasing number of countries have set carbon neutrality targets through legislation. This study evaluates the performance of countries with legislated carbon neutrality targets in reducing carbon emissions and explores the historical factors influencing these reductions. We applied the Kaya identity to decompose emissions into GDP per capita, energy intensity, and carbon intensity. Time series K-means clustering with dynamic time warping was used to analyze emissions data from 1971 to 2021 for 25 countries that have enacted such legislation. The results identified three emission trend groups: decreasing, inverted U-shaped, and increasing. Key characteristics of these groups provide insights into the progress of these legislating countries. First, energy intensity and carbon intensity were significant factors across all groups. Second, carbon intensity was more influential for the decreasing group, while energy intensity played a larger role for the inverted U-shaped and increasing groups. Third, some legislating countries remain locked into specific emission patterns and need to develop national strategic plans that align economic and technological development with emission reductions. This study contributes to understanding diverse yet interconnected pathways to carbon neutrality by considering the distinct emission trends among countries.