Compounding droughts and floods amplify socio-economic impacts

Abstract

In recent years, compound climate and weather extremes have received significant attention due to the heightened threat they pose to the environment, human societies, and the economy. This study investigates the impacts of compound drought-flood (CDF) extremes using data from two widely-used disaster databases: the emergency events database (EM-DAT) and its geocoded disasters (GDIS), along with the DesInventar database. The analysis covers the period from 1960 to 2018, consistent with GDIS’ temporal coverage. CDF events are defined as instances where drought and flood hazards occur concurrently or sequentially, with a flood taking place during a drought period or within four months of its end. Our findings for the global extratropics reveal that the economic losses and the number of affected people resulting from CDF events are up to eight times higher than those ascribed to isolated droughts or floods, with a confidence interval ranging from one to twelve. Similar qualitative results emerge from DesInventar and EM-DAT, albeit with some quantitative differences. Furthermore, impact ratios have increased in more recent decades compared to earlier periods, emphasizing the increasing impacts of the drought-flood compound events. These results highlight the amplified negative impacts when droughts and floods occur concomitantly or sequentially, underscoring the need for targeted policies to address their socioeconomic risks, particularly under changing climatic conditions.