Seite - 272 - in Loss and Damage from Climate Change - Concepts, Methods and Policy Options

272 A.Lopezet al. andonlythen(ifnecessary)appraisingtheirappropriatenessagainstadetailedsetof climate projections. In this context, the evaluationof climate risks is just one com- ponent of the estimationsof all the environmental and social stressors andchanges in socio-economic conditions that can induce system failures. Therefore the deci- sionmaker is encouraged to thinkbroadly about the interactions of other risks and prioritieswith the adaptation problemand look for strategies that have co-benefits with other areas such as development andDRR.This approachwas adopted in the Thames 2100Estuary project (Haigh and Fisher 2010) and includes, for instance, community-basedadaptationapproaches. Due to the complex, diverse, and context-dependent nature of CCA, it is cur- rently recognised that there isnosingleapproach toadaptationplanning,withsome evidencesuggesting that the linksbetweenadaptationplanningand implementation arestrengthenedwhenboth, thescience-drivenandthepolicy-drivenapproachesare combined (Mimuraet al. 2014). Thetopicofdecision-makingunderuncertaintyhasreceivedsignificantattention inthecontextofCCA(DessaiandHulme2007;Gilboa2009;Lempert2002;Lempert andCollins 2007; Ranger et al. 2010a, b; and seeMcDermott 2016 andHeal and Milner 2014 for overviews).Despite the fact that in somecases reliable and robust projectionsarenotpossible(insomecaseseventhesignofchangeisnotknown),there are now several decision-making tools that, recognising the inherent uncertainties, areused todeveloppublicpolicy,particularly in thecontextofadaptationandflood riskmanagement.SeeAppendix1 foranoverviewof someof themain tools. Examples include adaptivemanagement and scenario planning.Adaptiveman- agement allows for continuousmodification of a policy or a strategy to take into account new learning about future trends and impacts. This involves a highdegree of learning, experimentingandevaluation throughout the lifetimeof the strategyor policy.Scenarioplanningprovidesdecisionmakerswith a rangeofdifferent, plau- sible future scenarios. Policies and strategies can be tested against those scenarios to assess how theymayperform.For adaptationdecision-making these approaches have been developed into options analysis (Haigh and Fisher 2010; Ranger et al. 2010a, b; Dittrich et al. 2016) and portfolio analysis (Watkiss and Hunt 2016; Dittrichet al. 2016). RealoptionsanalysiswasusedintheThames2100Estuaryproject,withextensive sensitivity testingof sea level riseassumptions (i.e. incorporatingsomeelementsof robustness-basedanalyses) (Reeder andRanger2010).Gersonius et al. (2013) also applied the real options analysis to urbandrainage infrastructure inWestGarforth, England.