Seite - 75 - in Loss and Damage from Climate Change - Concepts, Methods and Policy Options

3 ObservedandProjected Impacts fromExtremeWeatherEvents… 75 warning and evacuation, andvulnerability has substantially declined (Mechler and Bouwer2015;BouwerandJonkman2018),monetarylossescanonlybesubstantially prevented from improved protection, such as through flood prevention, improved buildingconstruction,andalternativeagriculturalpractices.Therearehoweververy few longitudinal studies that haveassessed these effects over sufficiently longperi- odsover time, toestablish the long-termseffects, compared to increasingexposure. Thestudies indicatingsubstantial reductions inmonetary losseshaveconsideredthe most recent decades (Jongman et al. 2015;Kreibich et al. 2017), andwhile efforts mayhavebeen successful at improving the current situation, they canhardlymake upforsubstantialdevelopment invulnerableareas thathasbeentakenplaceover the last100years. Finally, for attributing changes in extreme weather impacts, in the context of LossandDamage, any remaining trendafternormalisationandafter accounting for vulnerabilityreductionwouldneedtobedemonstratedtohavearelationwithchanges inextremeweatherhazards.Andthischangeinextremeweatherhazardinturnshould beattributedtoanthropogenicclimatechange.Table3.3summarisestheresultsfrom thereviewof lossnormalisationstudies (Table3.2),aswellas theobservedchanges in weather extremes (Table 3.1). While for several weather extremes, increasing occurrencehasbeenobserved,andoftenalsoattributedtoanthropogenicgreenhouse gas forcing (Table 3.1), these changes are not reflected in loss records, or at least cannot be recognised.Nosubstantial evidence is present for long-term increases in normalised losses from these types of extreme weather, based on quantified loss records. And while a few studies show that losses from convective weather may have increased, in particular losses fromhail and thunderstorm events (Changnon 2001; Changnon 2009a;Kunz et al. 2009; Sander et al. 2013), these are yet to be linked to structural changes in theoccurrenceof convectiveweather events, related togreenhousegas forcing (IPCC2012,2013). Table3.3 Comparisonofchanges inextremeweatherhazards (regardlessofhumancontribution) andobservedchange in losses Type Increase inextremeweather hazard? Increase inobserved losses? Heatwave Very likely Unknown Heavyprecipitation Likely Unknown Riverfloods Limited/mediumevidence No increase Drought Lowconfidence Unknown Tropical cyclones Lowconfidence No increase Extra-tropical cyclones Likelypolewardshift No increase Extremesea-levels Likely Unknown Wildfires Unknown Noincrease Convectiveweather Unknown Possible increase?