2 How Climate Models Gain and Exercise Authority

Numerical climate models have become central to the unfolding story of climate change. Climate models underpin the knowledge claims and risk assessments of the Intergovernmental Panel on Climate Change (IPCC), claims and assessments which powerfully shape political narratives of climate change (Manuel-Navarette 2010) and animate new social movements (Jamison 2010). Climate models seem essential for the detection and attribution of anthropogenic climate change, heavily informing iconic expert judgements such as: “Most of the observed increase in global average temperatures since the mid-20^th century is very likely due to the observed increase in anthropogenic greenhouse has concentrations” (IPCC 2007a: 10; emphasis in the original). Climate models are also being deployed to attribute extreme weather events, such as individual heat waves or flooding episodes, to human influences (Pall et al. 2011). And numerical climate models offer novel access to the distant future by simulating the climatic consequences and their impacts of different development pathways being chosen around the world: “Anthropogenic warming could lead to some impacts that are abrupt and irreversible” (IPCC 2007b: 53). By anticipating the future in this way, climate models have become a prosthetic to human moral and ethical deliberation about long-term decision-making.