Progress towards mitigating climate change has been hampered by the large uncertainties surrounding its impacts and solutions, and the different approaches to valuing the associated risks. A new article appearing in the journal Nature Climate Change shows how this needs not to be the case. Using the latest data and methods from climate and decision science, researchers at Italian research institutes have generated ways to design efficient climate policies using the current state of knowledge about climate science and economics.

The polarization in the public and political debate over climate change has been exacerbated by the uncertainties which characterize it. On the one hand, it has been interpreted as a reason for postponing emission reductions, while on the other hand, it has been used as a precautionary argument in favor of stringent mitigation.

In principle, climate policies should consider the uncertainty characterizing the future impacts of climate change and the cost of mitigating it. However, quantifying such uncertainties is a complex and difficult task, involving the collection and analysis of future multiple scenarios based on scientific data, model runs, and experts judgments.

How should this vast body of information be synthetized and aggregated in a set of policy recommendations in the face of these uncertainties and different views of coping with them?

This is the question that underpins the article “Selection of Climate Policies under the Uncertainties in the Fifth Assessment Report of the IPCC”, published online by the journal Nature Climate Change. It is the output of Italian scientific research on climate change authored by CMCC and FEEM researchers Laurent Drouet, Valentina Bosetti and Massimo Tavoni.

The authors have drawn on the vast amount of data and information collected in the three volumes of the Fifth Assessment Report on Climate Change of the IPCC, which represents today’s most exhaustive and updated source of scientific knowledge on climate change. The information considered relates to climate scenarios, future temperature projections, climate change impacts and mitigation costs. They transformed this wealth of data into climate policies using different criteria from decision sciences.

The analysis of these variables, the related uncertainties and risk assessment has produced a study that, rather than defining a single optimal climate policy, allows decision-makers and the public to translate their preferences with respect to deep uncertainty, risk, and time into climate policy recommendations. The article shows that uncertainty is indeed a crucial factor in determining climate policies. It also shows that the traditional methods to treat uncertainty are unsatisfactory, and that reframing the climate change debate in terms of analytic risk management allows us to create a bridge between the more precautious scientific approach and the efficiency-based policy perspective.

L. Drouet, V. Bosetti and M. Tavoni, “Selection of climate policies under the uncertainties in the Fifth Assessment Report of the IPCC”, Nature Climate Change, DOI: 10.1038/nclimate2721

** The research leading to these results has received funding from the Italian Ministry of Education, University and Research and the Italian Ministry of Environment, Land and Sea under the GEMINA project, from the EU FP7 under grant agreement no. 308329 (ADVANCE) and from the European Research Council 336703-RISICO at IEFE, Bocconi University.