Seite - 268 - in Loss and Damage from Climate Change - Concepts, Methods and Policy Options

268 A.Lopezet al. judgment is required toestimate theuncertaintyof theprojected impacts (Boset al. 2015; IPCC2014a, b). Secondly, the applicability of the approach depends on the climatevariableand the location; forexampleDahindenetal. (2017) showthat it is oftennotpossible tofindanaloguesintemperatureandprecipitationsimultaneously. The abovediscussion refers specifically to the estimationof thehazard component of risk.Asalreadymentioned, the risk is, however, theprobabilityofoccurrenceof the hazardmultiplied by the impacts if these events occur. In the IPCCAR5 ‘cli- mate change impacts’ refer to “the effect on lives, livelihoods, health, ecosystems, economies, societies, cultures, services, and infrastructure due to the interactionof climatechangesorhazardousclimateeventsoccurringwithinaspecific timeperiod and thevulnerabilityof anexposedsocietyor system”(IPCC2014a). Therefore, the study of ‘climate change impacts’ requires impactsmodels that combineprojectionsof climatechangewith socio-economic scenarios.To this end, the Inter-Sectorial ImpactModel IntercomparisonProject (ISI-MIP) aims to study the impacts of climate change onfloodhazard, food andwater availability, health, ecosystems and coastal infrastructure, together with their interactions and uncer- tainties in order to provide a comprehensive picture of climate change risks (see Schellnhuber et al. (2014)and references therein). Whenconsidering the risk, includingexposure andvulnerability, at shorter time scales, inmanycases thecurrentnatural variabilityof theclimate systemandother non-climatic drivers of risks will have a higher impact than the climatic changes drivenbychanges inatmosphericconcentrationsofgreenhousegases.Forexample, in the near term, changes in exposure such as urbanization and building housing developments onflood-prone areas could increase significantly the riskofflooding anddamage to theaforementioned infrastructure, independentlyof climatechange. Over longer timescales, it is expected that anthropogenicclimatechangewill often playamoresignificant role (Oppenheimeret al. 2014). Theabovediscussionabout theestimationof theclimatehazardiscloselyrelated to,andbasedonsimilardiscussionsinthecontextofCCA.However,L&Dalsobrings somethingdistinctlyunique to thediscussion: embedded in thepolitical concept of L&D,atleastaccordingtosome,istheelementofburdensharingandcompensation, whichcouldrequire theestimationof theattributablefractionof lossesanddamages to human induced climate change. From the physical sciences point of view, and focusingon thequestionofattributionof theclimatehazardorphysical impact, it is clearthatestimationsofchangesinitslikelihooddonot,apriori,haveanyinformation aboutwhether or not the changingprobability canbeattributed3 tohuman induced climate change.Approaches that attempt to quantify the attributable component of thechanges in theprobabilityofoccurrenceofmeteorological hazards relyheavily onclimatemodels tocompare the likelihoodof theweather eventwithandwithout the influenceofanthropogenicemissionsofgreenhousegases.However, as already 3Asdefinedby the IPCC,detectionof climatechange is theprocessofdemonstrating that climate haschangedinsomedefinedstatisticalsense,withoutprovidingareasonforthatchange.Attribution of causes of climate change is the process of establishing themost likely causes for the detected change,eithernaturaloranthropogenic,withsomedefinedlevelofconfidence(source:IPCC2012).