Potential impacts of climate change on extreme precipitation over four African coastal cities

This study examines the impacts of climate change on characteristics of extreme precipitationevents overfour African coastal cities (Cape Town, Maputo, Lagos and Port Said) under two future climate scenarios (RCP4.5 and RCP8.5). Fourteen indices were used to characterise extreme precipitationand 16 multi-model simulation datasets from the Coordinated Regional Climate Downscaling Experiment (CORDEX) were analysed. The capability of the models to reproduce past characteristics of extreme precipitation overthe cities was evaluated against four satellite datasets after quantifying the observation uncertainties overthe cities. The models give realistic simulation of extreme precipitationcharacteristics overthe cities, and in most cases, the magnitudes of the simulation biases are within the observation uncertainties. For both the RCP4.5 and RCP8.5 scenarios, the models project a decrease in wet days and an increase in dry spells overthe four cities in the future. More intense daily precipitationis projected overMaputo, Lagos and Port Said. The intensity and frequency of extreme precipitationevents are projected to increase overLagos, but decrease overthe other cities. A decrease in annual precipitationis projected overCape Town, Maputo and Port Said, whilst an increase is projected overLagos, where the water surplus from the more extreme precipitationevents exceeds the deficit from the less wet days. A decrease in the number of widespread extreme events is indicated overall the cities. Wet-day percentile and all-day percentile methods signal opposite future changes in the extreme precipitationthresholds overthe cities (except overLagos). The results of this study may have application in managing the vulnerabilities of these coastal cities to extreme precipitationevents under climate change.