12. The 2°C Target Reconsidered

While the 2°C target has become an important reference point in the international climate-policy arena, as stated for example in the Copenhagen Accord in 2009, its scientific underpinning and its legitimacy is heavily debated in the scientific community. In this chapter, outstanding experts in the field, representing opposing viewpoints within the scientific community, present their view on the 2°C target. While Mike Hulme casts doubt on the usefulness of the very idea of a specific temperature target as guidance for mitigation policy, Claus Leggewie and Dirk Messner claim that the 2°C target has an important instrumental value in the discourse surrounding climate-related risks. We discuss both contributions and argue that climate stabilisation goals provide a useful framework for a consistent discussion of climate policy choices. We point out that the 2°C objective has two major merits: first, as a global climate stabilisation goal it provides a useful framework around which to structure the global climate policy debate. Second, we consider it an appropriate climate policy goal enabling currently available scientific knowledge to be combined with some explicit value judgements. Nevertheless, further research and public debate are required to reduce uncertainties and substantiate this conjecture.