[en] In a first part, the authors propose an overview of the history of the process of negotiations on climate, recall its framework and operation modalities (governance by the United Nations, operation of climate institutions), and outline geopolitical evolutions and significant landmarks (notably the Copenhagen conference). They also question the present credibility of negotiations on climate. Then, they focus on Europe as a major actor of this history, recall the different steps by which Europe gained a peculiar leadership status (Europe as an actor of international negotiations, relationship between climate and European building, evolution of the European ambition). Thirdly, by drawing some lessons from the 2012 Rio Conference, they give an overview of deadlocks, blocks and opportunities on the way to resolve the problem, not only within the United Nations framework but also at different scales. They notably discuss the evolution towards a large energy transition, and the position of Europe in front of commitments with respect to climate