Improving hydrological climate impact assessments using multirealizations from a global climate model

Many flood risk assessments account for uncertainties in future anthropogenic emissions by considering multiple representative concentration pathways (RCPs). The imperfect knowledge and representation of the climate system is considered with global models (GCMs). Yet, uncertainty introduced incomplete natural variability also relevant but not always accounted for. A set realizations provides improved insights presented GCM. This study explores potential using a from single GCM-RCP combination instead realizations. We use (subsets of) 16 EC-Earth RCP8.5 focus on three locations along Rhine. to avoid interference additional sources uncertainty. find that projected changes river flows highly depend realization chosen. Individual ensemble members provide different annual mean flow, extreme flows, regime shift. By increasing number combining their maxima value analysis, projections flow extremes converge. conclude gives overconfident possibly erroneous projections. In science, this well studied; however, assessments, it still often neglected.