Which Policy Instruments Do Governments Use, and Which Ones Do Researchers Study?

Which Policy Instruments Do Governments Use, and Which Ones Do Researchers Study? A use case for the Energy and Climate Policy Ontology Silvia Weko1[https://orcid.org/0000-0002-8180-7046], Aksornchan Chaianong1 [https://orcid.org/0000-0003-3817-2062], Johan Lilliestam1[https://orcid.org/0000-0001-6913-5956], Ioannis Milioritsas1[https://orcid.org/0009-0004-5193-0862], Germán Bersalli1,2[https://orcid.org/0000-0001-9375-4677] 1 Sustainability Transition Policy Group, Friedrich-Alexander-Universität Erlangen-Nürnberg 2 Research Institute for Sustainability – Helmholz Institute Potsdam 1. Introduction The climate crisis has led to increased engagement from governments around the world to mitigate emissions. At the same time, academia has increasingly focused on how this can be done as quickly as possible, and lively debates have emerged on the effectiveness of different policies at reducing greenhouse gas emissions. Yet, academics are often constrained by a lack of cross-country, comparable and detailed information on policies. This raises the question whether the existing academic debate on policy instruments is skewed towards evaluating certain policies. We therefore examine which policy instruments governments actually use to lower greenhouse gas emissions, and which instruments tend to be studied. To do so, we first suggest a typology of potential policy instruments based on data on climate policy gathered by the Climate Policy Database and the Climate Policy Radar, complemented by a preliminary academic literature review and input from climate policy researchers. We then conduct a literature review using this typology to identify which of these possible instruments are most often researched. We compare which policy instruments are studied to the policy instruments that governments implement using data from the Climate Policy Database to compare categories such as economic, regulatory, information, and voluntary instruments. At the same time, the results will serve as a use case to validate the proposed Energy and Climate Policy Ontology (NFDI4Energy Measure 4.5). The research demonstrates the importance of systems to harmonize the collection and analysis of climate policy data, which are currently lacking. In addition, it reveals blind spots in the current academic research on how different instruments impact emissions and decarbonization, for example, on regulatory instruments, which may be due to a lack of cross-national and machine-readable data. 2. Research approach One of the key barriers to climate policy research is the lack of detailed and accurate data on policy instruments that is comparable across countries. Climate and sustainability transitions research also focuses primarily on certain world regions, particularly Europe and North America although in the past years there has been an increasing focus on China. We therefore propose to explore which policy instruments are explored by research versus which policy instruments exist. Weko et al. | Climate Policy in Practice (2025) "NFDI4Energy conference" 2.1 Developing a policy instrument typology In order to analyze which instruments are most often analyzed and which ones are implemented by governments, we need to develop a common language to talk about policy instruments. Our first step was to examine existing policy instrument typologies and develop an interoperable policy typology which could incorporate instruments from the following sources: Table 1. Sources of policy instruments. Open Energy Ontology https://openenergyplatform.org/ontology/ Climate Policy Database (note: this source gathers data from the following key datasets and more: Climate Action Tracker, COMMIT, ECOLEX, EU Climate Mitigation Policies and Measures, IEA, UNFCCC, Climate Change Laws of the World, OECD, RES Legal, WTO Environmental Database). https://climatepolicydatabase.org/methodology Climate Policy Radar https://www.climatepolicyradar.org/ Hafner et al. https://zenodo.org/records/3371375 Peñasco et al. https://doi.org/10.1038/s41558-020-00971-x In addition, we solicited informal feedback from other climate and energy researchers in individual conversations and at academic conferences. This results in a preliminary list of 93 public policy instruments. This preliminary list serves as a framework for the literature review, which also validates the definitions and scope of instruments in the typology. 2.2 Identifying and coding academic publications We then use the policy typology to categorize academic publications in Scopus that explore the impact of policy instruments on greenhouse gas emissions and decarbonization. This is done in a series of steps: • Including relevant general keywords: We filter by papers that have the key term “policy” in their abstract or title, and one or more of the following key terms: “policy instrument, climate policy, climate mitigation, energy transition, renewable energy, emissions reduction, energy policy”. • Including relevant policy instrument keywords: We analyze papers that include one or more of the policy instruments included in the typology. • Identifying out-of-scope keywords: We exclude papers whose primary focus is on public support or backlash, as our focus is on policy instruments’ effectiveness at reducing greenhouse gas emissions. • Identifying out-of-scope publication types: We include only published academic papers, and exclude papers that include the terms “meta analysis” or “literature review”. This search resulted in 2450 publications, which were then exported for coding. Coders must then determine whether or not articles are in scope. As our analysis focuses primarily on the environmental impacts of climate and energy policies, we exclude the following from the analysis: • Papers that focus on public or political acceptance/climate justice only: Articles exclusively assessing public acceptance, the political process before and during implementation, energy/climate justice, or distributional impacts—without evaluating the environmental effectiveness of an instrument—are excluded. • Papers that focus on cost and/or economic effects only: Articles assessing only the (macro) economic effects of an instrument (e.g., impacts on GDP, public debt) or its cost (e.g., for households, firms) without evaluating its effectiveness are excluded. Weko et al. | Climate Policy in Practice (2025) "NFDI4Energy conference" • Other focus: Articles that do not focus on the evaluation of climate policy instruments are excluded. • Articles not available/not available in English: Articles that are not accessible or not in English are excluded. 3. Next Steps Our team is currently coding these abstracts. We will test our hypotheses above by comparing data on our coded body of literature and the most recent version of the Climate Policy Database, which contains over 10,000 instruments. In addition, the validation of the climate policy typology with the literature review will enable us to further develop the proposed typology into an ontology which will be integrated with the Open Energy Ontology. Funding The authors would like to thank the German Federal Government, the German State Governments, and the Joint Science Conference for their funding and support as part of the NFDI4Energy consortium. Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 501865131.