Advanced mathematics often plays an important role in risk evaluation, for example in relation to climate change. How can mathematics related classroom discussions enhance critical citizenship when societal issues are accompanied by advanced mathematics? In a master course in mathematics didactics, a figure from IPCC was discussed. The figure shows developments of the average global temperature changes. In this paper, we analyse the classroom discussion in accordance with Skovsmose's six reflection steps, with focus on societal aspects. The students reflect critically on the data used to support the figure, on characteristics of the models, on the models' significance in society and on their own participation in the classroom discussion. We discuss the results in a broader educational and societal context.