Geopolitical risks and port-related carbon emissions: Evidence and policy implications

Geopolitical risks (GPR) have emerged as a critical source of disruption in global trade and transportation systems, yet their environmental consequences on port-related emissions remain underexplored. This study examines the impact of geopolitical tensions on port-level carbon emissions using a monthly panel dataset covering 269 container ports across 40 countries and regions from 2016 to 2023. Employing a system generalized method of moments (SYS-GMM) estimator, we find that heightened geopolitical risks significantly increase carbon emissions at ports. A key mechanism underlying this relationship is that geopolitical tensions disrupt the vessel arrival schedules, which reduces port efficiency, and consequently increases emissions from ships at berth. Further heterogeneity analyses reveal that the environmental impact of GPR is more pronounced at ports serving larger container vessels, as these ports are typically involved in long-haul routes that are more exposed to geopolitical disruptions. In contrast, the impact is less significant at ports with fewer calling carriers, likely because dominant shipping lines tend to internalize the costs of inefficient berthing by smoothing vessel arrival times. This study provides novel empirical evidence on the environmental consequences of geopolitical shocks in the maritime sector, offering actionable policy insights for risk-sensitive and sustainable port governance.