Future Changes in Precipitation Extremes Over East Africa Based on CMIP6 Projections

Abstract

This paper presents an analysis of precipitation extremes over the East African region. The study employs six extreme precipitation indices defined by the Expert Team on Climate Change Detection and Indices (ETCCDI) to evaluate possible climate change. Observed datasets and CMIP6 simulations and projections are employed to assess the changes during the two main rainfall seasons of March to May (MAM) and October to December (OND). The study evaluated the capability of CMIP6 simulations in reproducing the observed extreme events during the period 1995 – 2014. Our results show that the multi-model ensemble (herein referred to as MME) of CMIP6 models can depict the observed spatial distribution of precipitation extremes for both seasons, albeit with some noticeable exceptions in some indices. Overall, MME's assessment yields considerable confidence in CMIP6 to be employed for the projection of extreme events over the study area. Analysis of extreme estimations shows an increase (decrease) in CDD (CWD) during 2081 – 2100 relative to the baseline period in both seasons. Moreover, SDII, R95p, R20mm, and PRCPTOT demonstrate significant OND estimates compared to the MAM season. The spatial variation for extreme incidences shows likely intensification over Uganda and most parts of Kenya, while reduction is observed over the Tanzania region. The increase in projected extremes during two main rainfall seasons poses a significant threat to the sustainability of societal infrastructure and ecosystem wellbeing. The results from these analyses present an opportunity to understand the emergence of extreme events and the capability of model outputs from CMIP6 in estimating the projected changes. More studies are encouraged to examine the underlying physical features modulating the occurrence of extremes incidences projected for relevant policies.

Projected changes in extreme rainfall and temperature events and possible implications for Cameroon's socio‐economic sectors

“…For characterizing daily features of precipitation and temperature extreme events over Cameroon, we analysed seven extreme event indices defined by the Expert Team on Climate Change Detection and Indices (ETCCDI, Sillmann et al, 2013; Zhang et al, 2011). The choice of the seven indices is based on the objective of characterizing how extreme events currently affecting Cameroon's socio‐economic sectors will respond in a warmer world, and they have been widely used for this purpose in many previous studies (e.g., Akinsanola et al, 2020a, 2020b, 2020c; Ayugi et al, 2021, 2022; Chou et al, 2009; Dosio et al, 2021; Haensler et al, 2013; Sillmann et al, 2013). The indices' identity, their names, definition and units are summarized in Table 3.…”

Evaluation and projection of mean surface temperature using CMIP6 models over East Africa

“…It is interesting to note that while the region is expected to warm rapidly, projections on precipitation show an increase in rainfall over the study domain (Shongwe et al, 2011;Ongoma et al, 2018;Osima et al, 2018;Ayugi et al, 2021). The expected recovery in precipitation is likely to offset the impacts of warming, which could adversely impact agriculture due to the sharp increase in evapotranspiration and subsequent increase in drought and aridity.…”

Projected future daily characteristics of African precipitation based on global (CMIP5, CMIP6) and regional (CORDEX, CORDEX-CORE) climate models

“…Also, Ukkola et al ( 2020) noted an increase in meteorological drought duration over southern Africa, Guinea and the northern African coasts in the CMIP5 and CMIP6 ensembles. Ayugi et al (2021a) found an increase in CDD, along with an intensification of extreme precipitation over East Africa, while Moon and Ha (2020) noted a thermodynamically driven increase in precipitation rates over the monsoon regions.…”

“…More recently, CMIP6 simulations have been investigated in terms of mean precipitation change at continental scale (Almazroui et al 2020) and for southern Africa (Sian 2021), and by extreme events over East Africa (Ayugi et al 2021a). In addition, Moon and Ha (2020) and Ukkola et al (2020) investigated future characteristics of (global) monsoon precipitation and meteorological droughts, respectively.…”