Speaker: Detlef van Vuuren, PBL Netherlands Environmental Assessment Agency and Copernicus Institute of Sustainable Development, Utrecht University, the Netherlands
Discussant: Evelina Trutnevyte, Renewable Energy Systems group, University of Geneva, Switzerland
Moderator: Johannes Emmerling, RFF‐CMCC European Institute on Economics and the Environment (EIEE), Centro Euro‐Mediterraneo sui Cambiamenti Climatici, Italy
The costs of climate policy are uncertain and depend on a wide range of factors, including uncertainties in socio-economic and technology development but also in the climate system. In the presentation, Detlef van Vuuren will illustrate the role of different uncertainties based on a metamodel from climate and integrated assessment models. Calibrating the meta-model to the model-based literature range allows it to go beyond the parametric uncertainty of individual models. The resulting median estimates for the cumulative abatement costs (at 5% discount rate) for 2 °C and 1.5 °C targets are around US$15 trillion and US$30 trillion, but estimates vary over a wide range (US$10–100 trillion for the 1.5 °C target). Interestingly, the sources determining this uncertainty depend on the climate target stringency. Climate system uncertainty dominates at high warming levels, but uncertainty in emissions reductions costs dominates for the Paris Agreement targets. In fact, costs differences between different socio-economic development paths can be larger than the difference in median estimates for the 2 °C and 1.5 °C targets. Developing simple metamodels in addition to more complex process-based models may help to explore implications of scenario uncertainty and identify research priorities.