Carbon footprint inequality: A scaling decomposition across 165 countries (1980–2019)

Individuals contribute to carbon emissions unequally. Yet, this inequality is often attributed solely to individual differences, overlooking the role of structural, societal-scale effects. Using a scaling framework, we analyze four decades of annual carbon footprint inequality data (1980–2019) across 165 countries. We uncover two distinct characteristics of high-emission groups: (i) Their emissions grow at a faster rate as population increases (societal-scale effects). (ii) They maintain higher emissions independent of population size (individual baseline). By proposing a counterfactual adjustment method, we reveal that baseline disparities are the dominant driver of inequality, while societal-scale effects also play a critical role. If all individuals shared the same return to scale as the bottom 10%, the global Gini index could be reduced by 18% and total emissions by 23%. Furthermore, we examine how these patterns vary across different economic contexts to inform more targeted policy. Our findings bridge individual and structural perspectives, advocating fairness-oriented climate policies that prioritize reducing baseline emissions while addressing the amplifying role of societal-scale effects.