Wealth-driven disparities in the social cost of carbon across Chinese provinces

The social cost of carbon (SCC) serves as a key metric for assessing climate policies and emission reduction targets; however, its accurate quantification requires better integration of socioeconomic and climatic factors. This study estimates China’s provincial SCC using an integrated framework that incorporates the inclusive wealth concept into integrated assessment models (IAMs), coupling shared socioeconomic pathways (SSPs) with representative concentration pathways (RCPs). We compute SCC across Chinese provinces under multiple scenario combinations from 1995 to 2100. The results reveal several key insights: First, under most scenarios, provinces with high SCC values are concentrated in the more developed eastern regions and resource-dependent western regions. For example, under SSP2 in 2100, SCC reaches 9.54 yuan/tC in Jiangsu and 9.78 yuan/tC in Guangdong, compared to 98.52 yuan/tC in Xinjiang. Second, the interplay between socioeconomic and climate pathways significantly influences SCC trajectories. The national SCC is projected to peak under the SSP3 pathway (reflecting regional rivalry), reaching 498.18 yuan/tC by 2100—substantially higher than under the sustainable SSP1 pathway (273.43 yuan/tC). Moreover, climate pathways exhibit nonlinear effects: contrary to conventional expectations, the national SCC under the high-emission RCP8.5 scenario (384.43 yuan/tC) is lower than under RCP6.0 (389.33 yuan/tC), highlighting the complexity of climate-economy interactions. Third, SCC estimates are highly sensitive to key parameter assumptions. A higher discount rate substantially reduces SCC; increasing it from 1.5% to 3.5% lowered the national estimate from 386.77 to 81.19 yuan/tC. Conversely, a higher adaptive investment growth rate elevates SCC by increasing the capital stock vulnerable to climate damages. This study demonstrates that China’s provincial SCC exhibits pronounced spatial heterogeneity and scenario dependence, offering important implications for the design of regionally differentiated climate policies and the optimization of provincial-level emission reduction investments.