biostudies-literatureKreibich HAustrian Science Fund FWFEuropean Research CouncilDutch Research Council (NWO)80-86https://www.ebi.ac.uk/biostudies/studies/S-EPMC9352573biostudies-literatureUnknown608(7921)Risk management has reduced vulnerability to floods and droughts globally^1,2, yet their impacts are still increasing³. An improved understanding of the causes of changing impacts is therefore needed, but has been hampered by a lack of empirical data^4,5. On the basis of a global dataset of 45 pairs of events that occurred within the same area, we show that risk management generally reduces the impacts of floods and droughts but faces difficulties in reducing the impacts of unprecedented events of a magnitude not previously experienced. If the second event was much more hazardous than the first, its impact was almost always higher. This is because management was not designed to deal with such extreme events: for example, they exceeded the design levels of levNatureThe challenge of unprecedented floods and droughts in risk management.PMC9352573948601I 4776016.161.324771678Grima JOAbeshu GWLLasat MCKhoi DNDelus CKieboom NGuzman DARiegel JNhi PTTSteinhausen MWagener TGain AKSazonov AWendt DEZambrano-Bigiarini MCarlson HSorensen JFrancois DVorogushyn SWang YBiancamaria SBalkhi LSharma SYang LHuning LSErfurt MLavado-Casimiro WDi Baldassarre GAznar BAlvarez-Garreton CKoutroulis ABuytaert WNgo-Duc TFreer JLi HYNguyen HQSairam NStahl KTran TVTFrolova NSchroter KSadik MSStoelzle MBos-Burgering LMazzoleni MCouasnon AQuintana-Segui Pde Ruiter MCAghaKouchak Avan Vliet MTHWickham EMcKenzie AMens MWard PJRazavi SCoxon GMendiondo EMBarendrecht MHMejia AKreibich HArguello Souza FASavelli EDaliakopoulos IGrillakis MMacdonald DTang QBloschl GEsposito GKharlamov MAgafonova SVan Loon AFMard JKireeva MTian FIonita MThao Nguyen Huynh TBudiyono YTokarczyk TVan Huijgevoort MHJTovar CAksoy HFrappart FCavus YMobini SRidolfi EMohor GSSzalinska WNagavciuc VMathew-Richards HPetrucci OBradley CCapewell LfalseThe challenge of unprecedented floods and droughts in risk management.Risk management has reduced vulnerability to floods and droughts globally^1,2, yet their impacts are still increasing³. An improved understanding of the causes of changing impacts is therefore needed, but has been hampered by a lack of empirical data^4,5. On the basis of a global dataset of 45 pairs of events that occurred within the same area, we show that risk management generally reduces the impacts of floods and droughts but faces difficulties in reducing the impacts of unprecedented events of a magnitude not previously experienced. If the second event was much more hazardous than the first, its impact was almost always higher. This is because management was not designed to deal with such extreme events: for example, they exceeded the design levels of lev2022-01-01T00:00:00Z2022 Aug2025-04-21T22:26:17.255Z2025-02-19T02:25:00.167ZS-EPMC93525733592250110.1038/s41586-022-04917-5