This chapter uses the story of the 1.5° target to discuss the relationship between science and politics at the Parties to the Climate Convention (COP). It presents the dominant framing of the climate problem and science's role in that framing, and examines the Copenhagen COP, the shift in climate governance and the history of the 2° long-term goal. The emergence of the 1.5° target and the resulting disagreements among scientists may be seen as a politicisation of this domain that led to a weakening of the sciences' role. The debate around the Paris COP has focused instead on the "easibility" of the 1.5° target. Since the official adoption of the 2° target in 2009, greenhouse gas emissions have risen further, making the goal increasingly inaccessible and yet in Paris an even more stringent target was being proposed. The result of a political and scientific co-construction, the 2° threshold benefited from a clear legitimacy.