The goal of the Paris Agreement to keep global warming well below 2°C can only be reached if countries commit to and adopt ambitious climate change mitigation action. However, we often witness a gap between both aspects. While many countries are not able to keep up with their promises, others even outperform their international commitments regarding climate change mitigation.

The following questions are addressed:

• To which degree and under which conditions do countries translate their international commitments regarding CC mitigation into their domestic policies (i.e. policy objectives and instruments)?
• What drives countries to under- or outperform?

This project aims to quantify and qualify the gap between international promises and national implementation. To this end, we advance an interdisciplinary theory that involves political actors from the international, national, and subnational level and the harmonization of policies between those levels. To measure this harmonization of climate change mitigation (the dependent variable), we create a vertical policy harmonization index, which reflects the divergence between international commitments and national implementation. Explaining the gap, we probe relevant macro-economic and political factors. Further, the project examines normative questions linked to vertical policy harmonization, like democratic legitimacy at both levels of decision-making, the relative success of autocracies in international bargaining agreements, and the type of bargaining strategies most beneficial to protecting the global climate.

We combine several research methods including policy network analysis, expert interviews, econometric analysis, and forecasting political negotiation outcomes. We use both qualitative and quantitative data collection methods. In addition, a computer scientist will develop, maintain, and store large-scale datasets.

Our results will provide normative guidance on the set-up of institutions and specific advice for actors striving to reduce the gap between international commitments and domestic policy adoption. The results also provide a basis for a more realistic prediction of the level of the ambition gap. We partner with several NGOs to involve external and practical expertise in almost all research tasks and to disseminate the results to UNFCCC delegates, national governments, and other decision-makers.