Methane emissions from landfills in China: Historical trends, future trajectories, and mitigation strategies

• Landfill methane in China peaked at 1.8 Mt in 2019, then dropped to 1.6 Mt in 2021. • Eastern China cut emissions by 16.2 %, while other regions saw steady growth. • Cumulative landfill methane could reach 29.10 to 30 Mt by 2050 under current trends. • Integrated strategies could cut landfill methane emissions by up to 88.4 % by 2050. • Half waste works best in rich regions, organic waste treatment suits poorer areas. Waste sector represents a significant source of anthropogenic methane emissions in China, however, its spatial distribution, future trajectories, and mitigation potential remain underexplored. This study presented a provincial-level methane emission inventory (2003-2021), revealing a rise from 1.0 Mt in 2003 to 1.8 Mt in 2019, then decline to 1.6 Mt in 2021 due to increased incineration. We applied panel data regression models and five Shared Socioeconomic Pathways to project emissions, estimating cumulative emissions could reach 29.10-30 Mt by 2050. Based on BAU scenario, mitigation effectiveness ranked as: organic waste treatment (58%), half waste (50%), LFG utilization (44%), and landfill renovation (33%). An integrated mitigation strategy could achieve up to 88.4% abatement. Spatial heterogeneity analysis revealed half waste strategies policies worked best in high-income provinces, while organic waste treatment strategies was optimal in low-income regions. These findings underscore the need for targeted and comprehensive strategies to significantly reduce landfill methane emissions.