Economic and ecological inequality of urban scale carbon emissions aggravated over time in China from a social-ecological system perspective

Understanding the spatiotemporal carbon inequality in China is crucial for guiding ecological strategies and energy utilization across regions. However, there are still few studies simultaneously investigating economic and ecological inequalities of urban carbon emissions in China. Here, employing a multi-regional input-output model, trade-related terms, and the Gini coefficient, we quantified the changes in inequality in economic benefits and ecological endowment of urban carbon emissions in China from 2012 to 2017. We found that: (1) Economic inequality of carbon emissions has increased in China. Specifically, cities in the bottom 20% of the total value added accounted for 39% of the total CO₂ emissions in 2012, which increased to 44% in 2017. (2) Substantial ecological inequality in carbon emissions persisted, as regions with a 20% share of EcoNPP (net primary productivity that remains in ecosystems, a measure of carbon sequestration capacity) accounted for 91% of CO₂ emissions. This study provides a novel dual perspective on carbon inequality by integrating economic benefits and ecological endowments at the urban scale, and the observed inequality underscores the significant challenges many Chinese cities face in achieving Sustainable Development Goals (SDG) 8.2 (promoting economic growth and efficient employment) and SDG 12.2 (achieving sustainable management and resource use), which are essential to the achievement of carbon neutrality.