The EU has undergone a deep transformation in the last 25 years. The goals adopted by the EU at the international level in climate negotiations have led to the internal adoption of goals by the EU member states. The book examines the changes experienced by the European Union that have gone on in parallel to its leadership in climate negotiations since 1992 and analyses whether combating climate change has contributed to the transformation of European policies.The book takes an in-depth look at the greenhouse gases (GHG) emissions reduction goals adopted by European states, the leadership of the EU in climate negotiations, the creation of the Energy Union, the commitment to a model of sustainable development, the promotion of a circular economy and the enhancement of cities, as relevant actors in the reduction of emissions and boosting of sound environmental practices.