中文摘要
环境外部性——即施加于他人且未获补偿的损害——是气候变化、污染、森林砍伐和生物多样性丧失的根源。然而，关于外部性如何驱动私人决策的经验证据仍然有限。我们利用覆盖印度尼西亚超过10.7万起火灾的15年逐日卫星数据，研究非法焚烧热带森林这一行为。天气引起的火灾蔓延风险变动，以及周边土地所有权的差异，使我们能够识别外部性在多大程度上影响了用火决策。相较于所有蔓延风险均被内部化的情形，我们发现，当企业周围是产权薄弱的未出租政府土地时，企业会过度用火。相反，与科斯定理一致，企业对邻近私人特许经营地所面临风险的处理方式，与对其自有土地所面临风险的处理方式相似。政府制裁主要集中于蔓延至人口聚居区的火灾，也能起到遏制用火的作用，这与庇古式威慑相一致。
Abstract
Abstract Environmental externalities—uncompensated damages imposed on others—lie at the root of climate change, pollution, deforestation and biodiversity loss. Empirical evidence is limited, however, as to how externalities drive private decision making. We study one such behaviour, illegal tropical forest fires, using 15 years of daily satellite data covering over 107,000 fires across Indonesia. Weather-induced variation in fire spread risk and variation in who owns surrounding land allow us to identify how far externalities influence the decision to use fire. Relative to when all spread risks are internalized, we find that firms overuse fire when surrounded by unleased government lands where property rights are weak. In contrast, and consistent with the Coase Theorem, firms treat risks to nearby private concessions similarly to risks to their own land. Government sanctions, concentrated on fires spreading to populated areas, also deter fires, consistent with Pigouvian deterrence.