Professor Mike Hulme (UEA): How do Climate Models Gain and Exercise Authority?

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, activity which powerfully shapes political narratives of climate change. Climate models are essential for the detection and attribution of anthropogenic climate change; and they offer access to the future by simulating the climatic consequences of the development pathways we have chosen and are choosing. Climate models have therefore acquired significant authority in the contemporary world: they exercise power and influence over the academy, over policy debates, over the human imagination.  The question I wish to answer in this lecture is ‘How do climate models gain and exercise this authority?’ There are two inter-related dimensions to this question which need examination: the source of climate models’ epistemic authority and the source of their social authority.  Epistemic authority comes from models using mathematical expressions of physical theory to represent reality. And yet climate models remain significant abstractions and simplifications of reality. Climate models’ social authority resides in the interactions between scientific practices and political interests which endow models with the status of trustworthy ‘witnesses’. To assist in this investigation, a four-fold typology of climate model reliability will be developed: coding precision; statistical accuracy; methodological quality; and social acceptability.