Have IPCC SPMs shifted towards discussing more solutions in the past two decades?

The Intergovernmental Panel on Climate Change (IPCC) regularly publishes summaries for policymakers (SPMs) based on its assessments of climate change science following the principle of policy-neutrality. As the urgency of climate change grows, there have been calls for IPCC assessments to be more solution-oriented, which means to assess specific policy instruments. Yet, there is a scholarly debate regarding whether and how it is possible to discuss specific policy instruments while staying policy-neutral. To inform this debate we conduct a content analysis of all Working Group III SPMs published in the last two decades. Dividing SPM content into strategic, argumentative and practical knowledge on mitigation policy instruments, we find that there is limited coverage of practical knowledge with only small changes over time. This suggests that IPCC assessments have not become more solution-oriented while abiding by their policy-neutrality principle. On the other hand, we find that SPMs have shifted from emphasizing the cost-effectiveness of mitigation towards emphasizing projections of required emissions reductions. Part of these changes may be explained through the evolution of ideas in global climate negotiations. Regardless of whether it chooses to amend its policy-neutrality principle, we recommend that the IPCC still shift more to discussing solutions. For example, the IPCC could better support the growing ecosystem of national and local boundary organizations which can broker context-specific knowledge on policy instruments.