This lecture explores the concept of environmental impact and efficiency, focusing on the IPAT formula and the Kaya decomposition. It discusses relative and absolute decoupling, the history of IPAT, and its limitations. The instructor analyzes CO2 emissions from various sectors, such as aviation and motor fuel consumption, and highlights the rebound effect. The lecture concludes with a discussion on green growth, the challenges of achieving absolute decoupling, and potential projects for further analysis.