Carbon Leakage from Fuel Taxes: Evidence from a Natural Experiment
利用葡萄牙燃油税上调的自然实验，发现柴油销售在西班牙边境地区增长6-9%，导致碳泄漏相当于葡萄牙公路运输年减排承诺的14-20%，表明重型车辆策略行为削弱了气候政策效果。
Abstract We exploit a fuel tax increase in Portugal to identify its effect on cross-border fuel sales and associated carbon leakage in the Spanish border regions. Using a difference-in-difference strategy, we find that while gasoline sales remained unaffected, diesel sales in Spanish border regions increased by 6–9%. Synthetic control methods confirm these estimates and attribute this differential effect by fuel type to routes frequented by heavy-duty vehicles, with large diesel tanks. We estimate a carbon leakage equivalent to 14–20% of Portugal’s annual mitigation commitment for road transport emissions. Our findings imply that heavy goods vehicles’ strategic behavior undermines the potential mitigation effects and revenue gains of transport climate policy, underscoring the need for coordinated policies in similar federal or quasi-federal contexts.