Compound climate extremes: attribution and risk assessment to different compound extreme events in Africa

Abstract

Detection and attribution of climate extremes in Africa has predominantly focused on univariate analysis of drought events and heat waves in different regions of the continent, although there have been unusual extreme events such as the Ethiopian heavy rainfall and flooding events in 2020, the 2022 flood in Nigeria and the 2020-2022 persistent drought event over Eastern Africa. Furthermore, the compounding of such type of extremes has not been investigated on the African continent so far.Decision makers and climate practitioners need context-specific and reliable information about the magnitude of climate risk for humans, socioeconomic and environmental sectors. Compound climate extremes (different combinations of heavy precipitation, floods, heat waves, droughts, and high discharge) are known for their large devastating impacts resulting from their concurrent or in-close-succession occurrence. Furthermore, the conventional univariate risk assessment can lead to under underestimated risk. Although risk analysis for compound extremes is a recent research topic globally, lack of such information is more acute for developing regions.Therefore, in this study, we conduct a detection and attribution study on the recent extreme events using a univariate analysis. In addition, we assess whether there was compounding of multiple extremes events using event coincidence analysis in different regions of the African continent. We use bivariate fraction of attributable risk method to take dependence between compounding events into account. We also assess sector-specific risks of compound climate extremes in the historical period and in the future using climate projections over Africa. Our risk analysis will be based on the recently proposed bottom-up approach and multi-criteria risk assessment, and follow procedures: prioritizing specific aspects of a sector of interest based on national and regional priorities, examining relevant climate and societal drivers, defining compound extremes, vulnerability assessment, preliminary analysis of risk assessment and refining the analysis for a detailed risk assessment.   Keywords: detection and attribution, risk and vulnerability assessment, compound climate extremes, heat waves, droughts, floods, climate change