Recurring and Co-Occurring Climate Extremes in Eastern Africa. A Normalcy?

Recurring and co-occurring extreme climate events exacerbate adverse effects on human livelihoods, regional and local economy, and the environment. Previous studies have extensively researched on the frequency, intensity, and duration of single climate extremes. However, recurring and co occurrence compound extremes remain scantly addressed in the East Africa Region. Here, we examine spatial variations of the precipitation and temperature extremes events from 1991 to 2022 (32 years) in East Africa, where agriculture is the main economic mainstay. We used high-resolution (0.25° x 0.25°) precipitation and temperature ERA5-reanalysis data. Three agriculturally relevant precipitation events: consecutive dry days (CDD), consecutive wet days (CWD), annual total precipitation that is wet-days annual amount (RR ≥ 1 mm)(PRCPTOT),  and three core temperature metrics: summer days with temperature > 25°C (SU25), extremely hot days with maximum temperature > 35°C (SU35) and diurnal temperature range (DTR) are examined. Our results show that the mean annual CDD ranges between 0 and 240 days in DR Congo, Uganda, Kenya, and the Ethiopian Highlands. The CWD annual averages were the longest, and the maximum was observed in some parts of DR Congo, Ethiopian, and Kenya highlands (365 days). However, minimum CWD events were experienced in the whole of Somalia and arid and semi-arid lands (ASALs) of Kenya, Southern Sudan, and Tanzania. The highest PRCPTOT was experienced in high altitudes and rainforest biomes. Mean annual SU25 were low, predominating in mountainous regions with less than 100 days. Most parts of Kenya show the annual DTR between 10 °C to 12 °C, and few areas with values between 8 °C to 10 °C and between 12 °C and 15 °C. Rwanda and Burundi had values between 8 °C and 10 °C while Tanzania experienced values between 8 °C to 10 °C and between 10 °C and 12 °C. These agriculturally relevant climate extremes threaten people’s livelihood, which is highly dependent on rainfed agriculture. Therefore, contextual-specific adaptation strategies are imperative in minimizing socioeconomic loss and damaging adverse effects in the agriculture and water sectors. Early warning systems should be enforced over East Africa to minimize compounded climate risks.

Keywords: Climate Extremes; East Africa region; ERA5; Precipitation; Temperature.