Attributing Compound Events to Anthropogenic Climate Change

Abstract Extreme event attribution answers the question of whether and by how much anthropogenic climate change has contributed to occurrence or magnitude an extreme weather event. It is also used link impacts change. Impacts, however, are often related multiple compounding drivers. Because typically focuses on univariate assessments, these assessments might only provide a partial answer influence high-impact We present theoretical extension classical for certain types compound events. Based synthetic data, we illustrate bivariate fraction attributable risk (FAR) differs from FAR depending extremeness as well trends in dependence between contributing variables. Overall, similar smaller than if trend second variable comparably weak both variables moderate high, typical situation temporally co-occurring heat waves droughts. If have similarly large weak, FARs larger likely more adequate quantification influence. Using model ensembles, apply framework two case studies, recent sequence hot dry years Western Cape region South Africa spatially droughts crop-producing regions Lesotho.