Global cereal trade under relaxed geopolitical frictions: distance-prioritized reallocation and implications for transport costs and CO₂ emissions

Introduction – Amid rising concerns over the fragility of global cereal supply chains under geopolitical tensions, infrastructure underutilization, and decarbonization pressures, this study examines how counterfactual reallocation can reshape the cost-emissions profile of international cereal logistics under transparent allocation rules. Methods – The analysis combines bilateral cereal trade data with dyadic conflict information from the Uppsala Conflict Data Program (UCDP) to identify politically tense links during non-war periods. Missing route-mode freight costs are imputed using mode-specific regression models. A distance-prioritized, capacity-constrained sequential allocation rule then reallocates trade flows toward geographically proximate feasible partners subject to export-capacity and import-demand constraints, under a counterfactual benchmark of relaxed geopolitical frictions. Results – Under this benchmark, 76 bilateral links that are inactive in the observed baseline receive positive trade volume. Aggregate transport work falls from 1.91 to 1.40 trillion ton-km, while system-wide emissions decline by approximately 21 to 70%, depending on the mode-assignment rule. Belt and Road Initiative corridors show larger proportional emissions reductions than the global average, whereas conflict-linked corridors experience distributional shifts in which their shares of system-wide costs and emissions can rise even when total emissions decline. Discussion – The findings are best interpreted as scenario benchmarks that clarify how distance compression, modal composition, and corridor-level burden shifting jointly shape the efficiency and sustainability of global cereal logistics under relaxed geopolitical frictions.