Agriculture stands as one of the most significant anthropogenic contributors to the emissions of methane (CH4) and nitrous oxide (N2O), potent greenhouse gases that exacerbate global climate change. Efforts to curtail non-CO2 greenhouse gas emissions from agricultural activities are increasingly recognized as critical components of global climate mitigation strategies. China, being the world’s predominant emitter in this category due to the scale of its agricultural sector, faces an urgent need to reconceptualize and transform its agricultural practices. Achieving carbon neutrality by 2060 requires an urgent deep transformation, focusing on nuanced, region-specific solutions underpinned by robust emission assessment frameworks.
In a pioneering advancement, researchers from Renmin University of China in collaboration with the International Institute for Applied Systems Analysis (IIASA) have introduced the Agricultural non-CO2 Greenhouse Gas Inventory (AGAIN) model. This novel framework provides a comprehensive toolset for evaluating long-term provincial emission trends and assessing mitigation potentials within China’s agriculture. The AGAIN model fills a critical gap by offering detailed projections that integrate policy effects and encompass all major emission sources, including the often-overlooked freshwater aquaculture sector, facilitating unprecedented accuracy and comprehensiveness in agricultural emission inventories.
Currently available subnational emission inventories have offered valuable insights but suffer from notable deficiencies. Notably, most lack long-term projections that account for the evolving landscape of mitigation policies and technological adoption. Additionally, freshwater aquaculture—a rapidly expanding agricultural sub-sector in China—has been either neglected or underrepresented, leading to systemic underestimation of CH4 emissions. Against this backdrop, the AGAIN model’s incorporation of these dynamics represents a significant leap forward in China’s emission evaluation capabilities.
The research team constructed an analytical scenario framework encompassing four distinct trajectories of agricultural emissions based on varying levels of policy implementation and technology adoption. The Business-as-Usual (BAU) scenario assumes a continuation of current trends without any additional mitigation policies, projecting a steady increase in emissions. Contrasting this, the Current Policy (CP) scenario integrates existing governmental mitigation efforts, yielding modest emission reductions and an earlier peak in emissions. The Conventional Technical Potential (CTP) and the Maximum Technical Potential (MTP) scenarios explore more ambitious adoption of mitigation technologies, thereby quantifying the upper limits of what is technologically feasible.
Projections under the BAU scenario paint a stark future, with agricultural non-CO2 emissions expected to escalate to 1,124 million tonnes of CO2 equivalent by 2060, underscoring the imperative of intervention. The CP scenario’s mitigation actions facilitate an earlier emissions peak around 2050 and a tangible 12% reduction by 2060. However, the effectiveness of current policies is limited, harnessing only about 26–45% of the total technical mitigation potential available. This discrepancy highlights a significant “mitigation gap,” emphasizing the need for stronger, more aggressive policy frameworks and technology deployment.
Provincial-level analyses within the framework reveal substantial spatial heterogeneity in emissions trajectories. Under current policies, 16 provinces are projected to miss their 2030 emission peak targets, suggesting regional disparities in mitigation capacity and effectiveness. Only under the MTP scenario does every province achieve emissions peaking before 2030, illustrating that full realization of technical mitigation potentials is essential to meet China’s broader climate goals. This outcome demonstrates the urgent necessity of tailoring mitigation strategies to local conditions, leveraging province-specific insights for enhanced policy precision.
A crucial innovation of the AGAIN model is the inclusion of freshwater aquaculture emissions in the national accounting framework. Conventional inventories often omit this source, leading to underestimation of methane emissions by approximately 15% and total agricultural non-CO2 emissions by about 10%. Given the rapid expansion of aquaculture in China, integrating this sector is not only scientifically necessary but also policy-relevant, ensuring that mitigation strategies encompass all critical emission sources and thus more accurately reflect the true climate impact of China’s agriculture.
The study underscores the significant potential for region-specific mitigation efforts that align local characteristics and policy priorities with technological capacities. The observed robust consistency in priority regions and subsectors across all modelled scenarios suggests that tailored mitigation pathways can be developed with confidence, improving both efficiency and political feasibility. This alignment can foster enhanced cooperation between local and national policymakers, optimizing resource allocation and maximizing climate benefits.
Professor Minpeng Chen, the corresponding author and a key architect of the AGAIN model, highlighted the transformative power of integrating detailed subnational data into emission inventories. By linking agricultural emissions data directly to administrative boundaries, policymakers gain pragmatic tools that facilitate regional emission targets, burden-sharing strategies, and targeted mitigation policy development. This represents a substantial improvement over gridded or aggregate national inventories that struggle to balance spatial resolution with operational value.
Looking ahead, the research team envisions iterative refinements to the AGAIN model that further elevate its accuracy and predictive sophistication. Incorporating dynamically evolving provincial policy targets, adaptive emission factors that reflect technological advancement and behavioral change, and considerations of regional food self-sufficiency are among the planned enhancements. These improvements will strengthen model robustness, offering more precise guidance for steering China’s agricultural sector towards sustainable, low-emission futures.
The significance of this research transcends China’s borders, offering valuable methodological insights and practical tools for other nations grappling with the challenge of agricultural non-CO2 greenhouse gas emissions. By providing a replicable framework that deepens understanding of sectoral emission dynamics and mitigative interventions, the AGAIN model presents a blueprint for bridging the gap between scientific assessment and pragmatic climate action at multiple governance scales.
This research effort was supported by the National Key Research & Development Program of China (2023YFE0113000) and Energy Foundation China (G-2304-34531), reflecting the strategic international and national investments dedicated to confronting climate change through interdisciplinary innovation. The cross-institutional collaboration between Renmin University and IIASA exemplifies the power of combining domain expertise with advanced systems analysis to tackle one of the most pressing global environmental challenges.
Published in the journal Energy and Climate Management on September 19, 2025, this study marks a seminal advancement in climate science and agricultural policy research. Its integration of cutting-edge modeling, comprehensive emission source inclusion, and policy scenario analysis sets a new standard for agricultural greenhouse gas inventory research and informs actionable pathways toward national and global emissions reduction targets.
Subject of Research: Agricultural non-CO2 greenhouse gas emissions, emission inventory modeling, and mitigation potential assessment in China
Article Title: Aligning China’s local and national carbon markets under global carbon pricing
News Publication Date: 19-Sep-2025
Web References: 10.26599/ECM.2025.9400018
Keywords: Methane emissions, nitrous oxide, agricultural greenhouse gases, emission inventories, China, climate mitigation, carbon neutrality, freshwater aquaculture, policy scenarios, emission projections, mitigation potential, subnational emissions
