Seite - 67 - in Loss and Damage from Climate Change - Concepts, Methods and Policy Options

3 ObservedandProjected Impacts fromExtremeWeatherEvents… 67 Thischapterbuildsonpreviousmajorreviewsofchangesinpastextremeweather eventsandtheirimpacts,includingtherelevantsummariescontainedinIPCCreports, suchas theSpecialReportonManaging theRisksofExtremeEventsandDisasters toAdvanceClimateChangeAdaptation (IPCCSREX; IPCC2012), aswell as the FifthAssessmentReport(IPCC2013,2014),andextendsthesewithrecentpublished studies. In addition, it provides a discussion of expectations of future losses under projected climate change. The discussion is complementary to other chapters that focus on the attribution of anthropogenic climate change (chapter by James et al. 2018), anddecisionmaking in the context ofLoss andDamage (chapter byLopez et al. 2018) aswell as on riskmanagement in the chapter byBotzen et al. (2018). The following topicsarecovered • Observedchanges inweather extremesand their relationwithanthropogenic cli- matechange; • Observedchangesinimpactsfromextremeweather,andtheirrelationtochanging weather extremes; • Observedchanges in exposure andvulnerability, leading to altered impacts from extremeweather; • Possiblechanges in thefuture in termsofextremeweather impactsandlossesand damages,basedonprojections fromquantitative impact studies. 3.2 ObservedChanges inWeatherExtremes The occurrence ofweather extremes has been studied extensively, both in natural hazard research for thepurposeofhazardprobability estimationanddesignofpro- tection, aswell as inclimatechange research.At thesame time,uncertainties in the attribution of extremes (such aswindstorms) to anthropogenic climate change are largerthanforslow-onsetprocesses(suchasannualaveragetemperaturechangeand sea-level rise) (IPCC2013). This is partly because of the rare nature of extremes, which are often analysed at return periods of 100 years ormore, and also because theyoftenoccuratspatialscalesthataresmallerthanslow-onsetevents.Forinstance, tropical cyclonesoccurover smaller areas thanmajor heat-waveordrought events. However,overrecentyearstheattentiontoextremeweathereventshasincreased,and possibilities toanalyseandmodel theoccurrenceand intensityof theseeventshave improved. For a number of extremeweather events, there is considerable evidence that thesehaveincreasedinfrequencyandforsomethatanthropogenicemissionsof greenhousegasesareamajorcauseof this increase. Table 3.1 provides an overview of past changes in weather extremes and the role of anthropogenic forcing, as assessed by the IPCC in the SREX (IPCC2012) and theWorking Group I volume of the Fifth Assessment Report (IPCC 2013). From this table it canbe concluded that the detectionof changes and attribution to anthropogenic emissions has been established for extremes related to temperature andsea-level rise.