Editing IPCC:AR6/SRCCL/Chapter-1 (section)

==== 1.2.2.3 Uncertainties in decision-making ====

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Decision-makers develop and implement policy in the face of many uncertainties (Rosenzweig and Neofotis 2013 <sup>[[#fn:r528|528]]</sup> ; Anav et al. 2013 <sup>[[#fn:r529|529]]</sup> ; Ciais et al. 2013a <sup>[[#fn:r530|530]]</sup> ; Stocker et al. 2013b <sup>[[#fn:r531|531]]</sup> ) (Section 7.5). In context of climate change, the term ‘deep uncertainty’ is frequently used to denote situations in which either the analysis of a situation is inconclusive, or parties to a decision cannot agree on a number of criteria that would help to rank model results in terms of likelihood (e.g., Hallegatte and Mach 2016 <sup>[[#fn:r532|532]]</sup> ; Maier et al. 2016 <sup>[[#fn:r533|533]]</sup> ) (Sections 7.1 and 7.5, and Table SM.1.2 in Supplementary Material). However, existing uncertainty does not support societal and political inaction.

The many ways of dealing with uncertainty in decision-making can be summarised by two decision approaches: (economic) cost-benefit analysis, and the precautionary approach. A typical variant of cost-benefit analysis is the minimisation of negative consequences. This approach needs reliable probability estimates (Gleckler et al. 2016 <sup>[[#fn:r534|534]]</sup> ; Parker 2013 <sup>[[#fn:r535|535]]</sup> ) and tends to focus on the short term. The precautionary approach does not take account of probability estimates (cf. Raffensperger and Tickner 1999 <sup>[[#fn:r536|536]]</sup> ), but instead focuses on avoiding the worst outcome (Gardiner 2006 <sup>[[#fn:r537|537]]</sup> ).

Between these two extremes, various decision approaches seek to address uncertainties in a more reflective manner that avoids the limitations of cost-benefit analysis and the precautionary approach. Climate-informed decision analysis combines various approaches to explore options and the vulnerabilities and sensitivities of certain decisions. Such an approach includes stakeholder involvement (e.g., elicitation methods), and can be combined with, for example, analysis of climate or land-use change modelling (Hallegatte and Rentschler 2015 <sup>[[#fn:r538|538]]</sup> ; Luedeling and Shepherd 2016 <sup>[[#fn:r539|539]]</sup> ).

Flexibility is facilitated by political decisions that are not set in stone and can change over time (Walker et al. 2013 <sup>[[#fn:r540|540]]</sup> ; Hallegatte and Rentschler 2015 <sup>[[#fn:r541|541]]</sup> ). Generally, within the research community that investigates deep uncertainty, a paradigm is emerging that requires the development of a strategic vision of the long – or mid-term future, while committing to short-term actions and establishing a framework to guide future actions, including revisions and flexible adjustment of decisions (Haasnoot 2013 <sup>[[#fn:r542|542]]</sup> ) (Section 7.5).

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