Auditing methods of renewable energy diffusion in climate scenario ensembles

Climate change scenarios and ensembles are growing in number and applications. However, the wide range of modelling outputs, whilst attempting to giving voice to a more inclusive and equitable research community, can delay the implementation of policies for the decarbonisation. This may occur due to the diffusion of scenarios with inherent opacity in the modelling assumptions, with the risk of exposing climate economic modelling and integrated assessment models to erosion of accountability and lack of credibility. In the context of energy system electrification, although renewable energies are strongly emerging as a pillar for the low-carbon transition, the questions which remain open about timeliness of interventions, magnitude of investments, local diffusion of low-carbon technologies, and their diffusion rates across the sectors are delaying the strengths of governmental interventions. Among the key grey areas of the modelling, there are choices or background assumptions that scenario and ensembles render opaque or invisible. Examples include dataset choices, where bias may inadvertently crop in as data result from collection efforts in different locations, by bodies with different profiles and interests. Opacity could be amplified by the trend of providing highly detailed representations of bio-physical and socio-economic processes. In fact, whilst the use of geo-referential data adds an enormous value to the modelling exercise, especially when addressing the local availability of renewables, this has the drawback of increasing the challenges to the full inspection of models and interpretation of outputs.

Here, we propose an auditing approach to analyse scenario and scenario ensemble. The framework promotes an inspection of scenarios and of scenario ensemble, allowing to define their taxonomy and classification in a format useful to support decision-making in the promotion of policies and investments in renewable energy for climate change mitigation. Considering the design of scenario and ensembles, we provide a review of audit tools that can be used to assess their credibility and policy-relevance.  We will consider not only renewable energy diffusion, but its interplay with key decarbonisation technologies, such as carbon capture and storage and nuclear energy. We will provide a framework for classifying and inspect the credibility of the scenarios. We will use the scenarios submitted to the Sixth Assessment Report of the IPCC in addition to those developed by other public and private institutions, as a basis to assess the data input accessibility and availability as well as to stress-test the usefulness of the methodology. The discussion will highlight the potential for a combined use of quantitative and qualitative tools for auditing scenarios and ensembles. Additionally, we identify key areas for future methodological research, including new benchmarks and machine learning tools for analysis. Building a wide auditing infrastructure for climate change modelling is a key step towards achieving greater transparency and accountability. Achieving such a level of accountability, will be key for acccelerating the decarbonization pace and the diffusion of renewable energy.