Optimal Environmental Targeting in the Amazon Rainforest

This paper sets out a data-driven approach for targeting environmental policies optimally in order to combat deforestation. We focus on the Amazon, the world's most extensive rainforest, where Brazil's federal government issued a `Priority List' of municipalities in 2008 { a blacklist to be targeted with more intense environmental monitoring and enforcement. First, we estimate the causal impact of the Priority List on deforestation (along with other relevant treatment effects) using `changes-in-changes' (Athey and Imbens, 2006), finding that it reduced deforestation by 43 percent and cut emissions by 49 million tons of carbon. Second, we develop a novel framework for computing targeted optimal blacklists that draws on our treatment effect estimates, assigning municipalities to a counterfactual list that minimizes total deforestation subject to realistic resource constraints. We show that the ex-post optimal list would result in carbon emissions