Climate change scenarios have been a crucial component of the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) in understanding possible climate outcomes, impacts, and risks, and mitigation pathways. Drawing upon lessons learned from AR6 Working Groups experience, a new paper published on Nature Climate Action presents insights into the role of scenarios, including recommendations and opportunities for the upcoming IPCC assessment cycle.

The paper “Scenarios in IPCC assessments: lessons from AR6 and opportunities for AR7” published in Nature npj Climate Action presents lessons learned from the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC), which has been characterised by an unprecedented level of coordination and integration across Working Groups. However, their utilization within the assessment and the associated timelines posed coordination challenges that can be used to improve and make the work on the Seventh Assessment Report much easier and more effective.

The first author of the study is Anna Pirani, a senior research associate on climate risk and transformative adaptation strategies with CMCC. She is an executive editor of the IPCC Special Report on Global Warming of 1.5°C and the AR6 Working Group I 2021 Climate Report on the physical science basis of climate change, and an author of the IPCC AR6 Synthesis Report.

Abstract

Scenarios have been an important integrating element in the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) in the understanding of possible climate outcomes, impacts and risks, and mitigation futures. Integration supports a consistent, coherent assessment, new insights and the opportunity to address policy-relevant questions that would not be possible otherwise, for example, which impacts are unavoidable, which are reversible, what is a consistent remaining carbon budget to keep temperatures below a level and what would be a consistent route of action to achieve that goal. The AR6 builds on community frameworks that are developed to support a coherent use of scenarios across the assessment, yet their use in the assessment and the related timelines presented coordination challenges. From lessons within each Working Group (WG) assessment and the cross-WG experience, we present insights into the role of scenarios in future assessments, including the enhanced integration of impacts into scenarios, near-term information and community coordination efforts. Recommendations and opportunities are discussed for how scenarios can support strengthened consistency and policy relevance in the next IPCC assessment cycle.

For more information:

Pirani, A., Fuglestvedt, J.S., Byers, E. et al. Scenarios in IPCC assessments: lessons from AR6 and opportunities for AR7. npj Clim. Action 3, 1 (2024). https://doi.org/10.1038/s44168-023-00082-1