For more than three decades, the European Union has been recognised as a world leader in the fight against global warming and climate change. Climate policy has become a dominant issue on the EU's environmental agenda and has gradually been integrated into other policy areas, most notably energy policy. In terms of climate and energy policy, the EU has developed the most advanced and comprehensive regulatory framework in the world, which includes both EU-wide policies and targets to be achieved by Member States. Taken together, these policies and targets serve to advance the energy transition – a process aimed at transforming Europe's energy sector from fossil fuel-based to zero-carbon, mainly through the use of renewable energy and energy efficiency measures. However, the process is uneven in the different Member States. This lecture will present the development of European climate and energy policy, in the context of global climate politics. It will also illustrate different trajectories for the development of renewable energy policies, comparing two different case studies: Poland and Germany. Finally, it will discuss the current challenges of further developing the energy transition in the context of Russia's invasion of Ukraine in 2022.