Carbon mitigation potential of deploying energy crops on marginal lands in China under climate change scenarios

Carbon benefit assessment of energy crop deployment (ECD) is crucial for achieving climate commitments, yet the current lack of a comprehensive evaluation framework integrating climate change impacts creates knowledge gaps that may undermine policymakers' confidence in climate actions. To address this, this study developed a spatially explicit integrated assessment framework by combining multiple methodologies to quantify the carbon benefits of ECD under current and future climate scenarios. Results reveal that under climate change scenarios, marginal land expansion offsets the negative effects of reduced land suitability on carbon mitigation potential (CMP), while biomass yield increase further amplifies this positive effect. In the baseline scenario, marginal land exhibits a CMP of 2.57 MT CO₂-eq, with significantly higher potential west of the Hu Huanyong Line than east of it, and its center of gravity gradually shifts westward under future climate scenarios. The marginal benefits of CMP show significant spatial heterogeneity across climate scenarios, with saturation effects diminishing incremental contributions and sensitivity as land suitability increases. Prioritizing carbon sink development in "high-resilience and high-marginal-benefit synergy zones" while avoiding high-emission pathways enhances policy efficacy. These findings provide critical insights for China to leverage marginal land for carbon sequestration through optimized energy crop deployment.