Strategies for Improving Carbon Emission Efficiency of Municipal Solid Waste Management System in Western China: A Transition toward Environmental Equity

Rapid urban expansion poses critical challenges for cross-regional municipal solid waste (MSW) management within the context of climate mitigation and sustainable development. While the energy substitution benefits of MSW are well documented, significant gaps remain regarding how regional integration can promote environmental equity in waste management. This study evaluates the carbon emission efficiency (CEE) of MSW management systems in 211 cities across Western China from 2008 to 2023, utilizing a coupled greenhouse gas emission and economic cost model. By integrating machine learning-optimized geo-detector models with flexible spatial scanning algorithms, we identified systemic renewable energy poverty risks across multiple spatial scales, revealed spatial disparities in environmental equity, and developed 90 policy scenarios to enhance CEE. The results indicate that (1) CEE in Western China exhibits a distinct core-periphery spatiotemporal pattern, characterized by widening regional disparities where disproportionate waste-to-energy conversion exacerbates systemic renewable energy poverty. (2) Energy poverty risks aggregate in plate-axis-patch patterns under multiscale spatial scanning, encompassing 69.44% of Zero-Waste Cities. (3) Although waste-to-energy offers the highest potential for efficiency gains in single-stage optimization, strengthening source separation and recycling via multistage synergistic optimization is critical for systemic sustainability. The regional integrated waste cogovernance framework established herein provides replicable insights for advancing environmental equity and energy justice, offering decarbonization pathways for rapidly urbanizing emerging economies worldwide.