This course explores the application of economic tools to environmental challenges, such as climate change, pollution, resource conservation, and biodiversity. It examines the origins and consequences of environmental externalities and evaluates responses by public and private actors. The course draws on theoretical and scientific foundations, as well as recent empirical work. Topics include core concepts such as externalities and public goods; policy instruments such as cap-and-trade markets, taxes, subsidies, and regulation; methods for valuing damages; and behavioural responses by consumers and firms.