AIM-ALPHA v1.0: A partial equilibrium model of global agriculture and land use at basin-level resolution

Abstract. This paper introduces AIM-ALPHA v1.0, a global partial equilibrium model that explicitly represents agricultural markets and land-use dynamics with high spatial resolution at the national and subnational river-basin levels. The model covers 166 countries on the demand side and 400 production units on the production side, balancing supply, demand, prices, trade, and land allocation across 23 agricultural commodities from 2015 to 2100. AIM-ALPHA is a comprehensive framework that analyses global socioeconomic and environmental challenges such as food security, climate change, biodiversity loss, and their mitigation. This paper describes the model structure, evaluates performance against historical data, and demonstrates application via a case study on the impacts of climate-change mitigation on global food security. Validation shows that AIM-ALPHA reproduces the historical statistics around 2015 and remains within ±10 % of observed values up to 2020, confirming numerical consistency. The baseline projections are broadly consistent with those of other integrated assessment and agricultural economic models. We also present a scenario analysis using a 1.5 °C climate-change mitigation pathway, which incorporates global carbon pricing, bioenergy expansion, and afforestation. The results show that agricultural production declines while food prices rise, reducing calorie intake, particularly in developing regions. The country-level resolution of the model reveals considerable heterogeneity within aggregated regions, with several developing countries in Africa and Asia facing particularly large reductions in food availability. Such distributional effects are largely obscured in more regionally aggregated models. These findings highlight the trade-offs between climate-change mitigation and food security and the importance of national-level assessments that capture socioeconomic and spatial heterogeneity. AIM-ALPHA serves as a comprehensive platform when exploring linkages between human and environmental systems and analysing sustainable land-use transitions and policy design at national and regional levels.