This lecture discusses the environmental impacts of mobility and transport, focusing on the factors affecting impact such as population growth, economic growth, and technology. It explores the external costs and benefits of transport in Switzerland, emphasizing the importance of reducing environmental impacts. The instructor presents various strategies to improve the 'T' in the IPAT equation, highlighting the need for sustainable practices and public intervention. Additionally, the lecture addresses the core responsibilities of authorities in mitigating environmental impacts and proposes actions to reduce these impacts through property rights and true cost assessments.