Bidirectional allocation method of provincial carbon emission allowances under China's 2030 carbon peak target: From equity and efficiency perspective

To address the shortcomings of existing research on provincial carbon emission allowance (CEA) allocation regarding connecting the current situation with future trends, balancing provincial development demands with responsibilities, as well as reconciling equity and efficiency, this study proposed a bidirectional CEA allocation method to guide China's 2030 carbon peak goal. Drawing on province-specific characteristics and multiple guiding principles, we designed 961 allocation schemes. An integrated evaluation system combining equity (via the extended Gini coefficient) and efficiency (via the Malmquist index) yielded 18 Pareto-optimal solutions. These schemes achieve a trade-off between equity (Gini coefficient 0.29–0.33) and efficiency (Malmquist index 1.010–1.015). The optimal schemes account for provincial heterogeneity: advanced regions such as Beijing, Shanghai, and Guangdong would reduce emissions below their 2020 levels under ten of the eighteen schemes, whereas regions such as Tianjin, Shanxi, and Shaanxi would still have room for emission growth across all schemes. By offering a suite of trade-off solutions, our approach equips policymakers with the flexibility to prioritize equity or efficiency according to regional needs. Additionally, tailored policy recommendations are outlined for advancing carbon dual-control mechanisms and crafting support measures reflecting provincial characteristics.