This course examines current debates on the green transition, understood here primarily as radically reducing and eliminating carbon emissions. We will discuss other key planetary boundaries but concentrate on CO₂ reduction and elimination strategies to enable analytical focus. We start from the observation that, despite the urgency and necessity of a profound green transition, and despite the easy availability of technological solutions, in the European Union green policy announcements and targets have proliferated, while actual decarbonisation efforts have until recently been relatively late, uneven, slow and often weak. The challenges around implementation are significant, however. To take just one example: how is the EU Green New Deal to be financed? We will examine both these relative failures and relative successes from different angles. In each policy field that we will discuss, typically a form of either technological or doctrinal optimism or complacency risks leaving key policies open to failure. By recasting the green transition as a series of political economy problems, we can better understand those policy vulnerabilities, how they have played out, and how they might be avoided or overcome. By paying particular attention to distributive outcomes, institutional legacies, and political mobilisation, we aim to identify the crucial fault lines in current policy.