Ottmar Edenhofer, is Deputy Director and Chief Economist at the Potsdam Institute for Climate Impact Research (PIK), Professor of the Economics of Climate Change of the Technical University Berlin and Co-Chair of Working Group III of the Intergovernmental Panel on Climate Change (IPCC). Moreover, he is director of the Mercator Research Institute on Global Commons and Climate Change (MCC).
Large-scale scientific assessments are needed to inform public policy adequately due to the complexity of social challenges, such as climate change. Yet, how can assessments of policy options be policy-relevant without being policy-prescriptive? This is particular relevant for the assessments carried out by the Intergovernmental Panel on Climate Change (IPCC) where hundreds of scientific experts review and evaluate the existing scientific knowledge, and integrate it across disciplines to make it policy-relevant. Can scientists—in their capacity as scientists—legitimately speak to power when their advice inevitably relies on both facts and values? The predominant technocratic and decisionist responses to this question misleadingly assume that facts and values can be neatly separated. Building on John Dewey’s philosophy, the “pragmatic-enlightened model” (PEM) of assessment-making refines existing pragmatic models. According to the PEM, policy objectives and their means can only be evaluated in light of the practical implications of the means. Learning about the side effects and synergies of the best means may require a revaluation of the policy objectives. Following the PEM, assessments would—based on a thorough problem analysis—explore alternative policy pathways, including their diverse practical consequences, overlaps and trade-offs, in cooperation with stakeholders. This may facilitate a learning process between scientists and decision makers about costs, risks and benefits of different options. To some extent, the IPCC Working Group III (AR5) has tried to conduct such a laborious interdisciplinary cartography of multiple objectives, multi-functional policy means and their many implications. Yet, besides overcoming research gaps and methodological problems in policy analysis, the cartography approach would require more willingness by decision makers, but also scientists, to openly and critically evaluate policies.