The Use of Decision Making Under Deep Uncertainty in the IPCC Provisionally Accepted

Robert Lempert^1* Judy Lawrence² Robert Kopp³ Marjolijn Haasnoot⁴ Andy Reisinger⁵ Michael Grubb⁶ Roberto Pasqualino⁶

• ¹RAND Corporation, United States
• ²Victoria University of Wellington, New Zealand
• ³Rutgers University Camden, United States
• ⁴Deltares (Netherlands), Netherlands
• ⁵New Zealand Agricultural Greenhouse Gas Research Centre, New Zealand
• ⁶University College London, United Kingdom

The Intergovernmental Panel on Climate Change (IPCC) exists to provide policy-relevant assessments of the science related to climate change. As such, the IPCC has long grappled with characterizing and communicating uncertainty in its assessments. Decision Making under Deep Uncertainty (DMDU) is a set of concepts, methods, and tools to inform decisions when there exist substantial and significant limitations on what is and can be known about policy-relevant questions. Over the last twenty-five years, the IPCC has drawn increasingly on DMDU concepts to more effectively include policy-relevant, but lower-confidence scientific information in its assessments. This paper traces the history of the IPCC’s use of DMDU and explains the intersection with key IPCC concepts such as risk, scenarios, treatment of uncertainty, storylines and high-impact, low-likelihood outcomes, and both adaptation and climate resilient development pathways. The paper suggests how the IPCC might benefit from enhanced use of DMDU in its current (7th) assessment cycle.