Résumé -Depuis vingt-cinq ans, le changement climatique anthropogénique est appréhendé comme une question d'environnement global. Les sciences du climat jouent un rôle primordial dans la construction du problème, qui se veut résumé par la formule « science speaks truth to power », science et politique étant supposées séparées et étanches. Ce cadrage jusqu'ici dominant est aujourd'hui ébranlé par l'échec des négociations internationales : il est devenu manifeste que le consensus scientifique ne suffit pas à engendrer des décisions politiques globales significatives. À l'heure de la COP de Paris, alors que se discute la nécessité de changer de paradigme dans la négociation, cet article veut s'interroger sur l'évolution des relations entre science et politique dans le régime climatique, en revenant sur la vision du rôle de la science et en évoquant les critiques, propositions et perspectives qui se dessinent à propos des modèles d'expertise.Abstract -Relations between science and politics in the climate regime: In search of a new model of expertise? Over the past 25 years, anthropogenic climate change has been addressed as a global environmental problem, which must be resolved by reducing human greenhouse gas emissions through a global agreement negotiated under the auspices of the UN. The role of sciences in the construction of the problem is essential and is aptly summarized by the claim that "science speaks truth to power," with science and politics assumed to be hermetically separated. Although this "linear model" is in fact largely inadequate to account for the much more complex links between climate science and politics, notably within the IPCC, it has long been hegemonic, leading to debates focused on science rather than political responses. This dominant approach has been undermined by the failure of international negotiations: it is now clear that scientific consensus does not suffice to produce significant global political decisions. It is now evident that climate change is a geopolitical, economic, and development problem as much as an environmental one. As the Paris CoP approaches, in a phase of political uncertainties and discussions around the need for a change of paradigm in negotiations, our paper examines critically the evolving relationship between science and politics in the climate regime, revisiting the role of science and discussing emerging critiques, proposals, and perspectives on models of expertise.Natures Sciences Sociétés, 23, supplément, S6-S18 (2015)