Projected changes in mean rainfall and temperature over East Africa based on CMIP5 models

Abstract

This study presents potential future variations of mean rainfall and temperature over East Africa (EA) based on five models that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and representative concentration pathways (RCPs): 4.5 and 8.5. In this study, climate simulations of two timeframes, a baseline period (1961–1990) and projection period (2071–2100), are compared. The models reproduce EA's bimodal rainfall pattern but overestimate and underestimate seasonal rainfall of October–December (OND) and March–May (MAM), respectively. Rainfall is projected to increase under the two scenarios. Larger increases in rainfall will occur during the OND season than during the MAM season and in RCP8.5 than in RCP4.5. During the last half of the 21st century, EA is likely to warm by 1.7–2.8 and 2.2–5.4 °C under the RCP4.5 and RCP8.5 scenarios, respectively, relative to the baseline period. Scenario uncertainty is projected to exceed model uncertainty from the middle to the end of the 21st century. The central parts of Kenya and the Lake Victoria Basin will witness the highest increases in seasonal rainfall. The probability density functions (PDFs) of future seasonal rainfall show a positive shift and a statistically insignificant increase in variance relative to the baseline. Thus, EA is likely to experience an increase in extreme rainfall events. Understanding the future climate variability in EA is important for planning purposes but these results are based on relatively course resolution models prone to bias and therefore should be used with caution. There is a need for further research on climate projections over EA, including determining the causes of the poor performance of global models in reproducing rainfall climatology and trends over the region.

Quantile Mapping Bias Correction on Rossby Centre Regional Climate Models for Precipitation Analysis over Kenya, East Africa

“…These results agree with recent reports over broader study domains that have shown decreasing trends in rainfall patterns towards the end of 20th century [45,47,48,57]. Further, these studies demonstrate continued declining annual rainfall trends for different future scenarios over the study domain [63][64][65]. On the contrary, the observed increment patterns during the OND season concur with studies that have reported overestimations of OND, also referred to as 'short rains' over the study region [65][66][67].…”

“…Further, these studies demonstrate continued declining annual rainfall trends for different future scenarios over the study domain [63][64][65]. On the contrary, the observed increment patterns during the OND season concur with studies that have reported overestimations of OND, also referred to as 'short rains' over the study region [65][66][67]. Yang et al [57] highlighted the aspect of challenges associated with simulations of atmosphere-ocean-monsoon interaction over the East Africa region as the primary cause of observed bias in models during OND and MAM projections.…”

Quantile Mapping Bias Correction on Rossby Centre Regional Climate Models for Precipitation Analysis over Kenya, East Africa

“…These results agree with recent reports over broader study domains that have showed decreasing trends in rainfall patterns towards the end of twentieth century (Yang et al, 2015;Ayugi et al, 2018;Mumo et al, 2019). Further, these studies demonstrate a continued declining annual rainfall trends for different future scenarios over the study domain (Rowell et al, 2015;Tierney et al, 2015;Ongoma et al, 2018). On the contrary, the observed increment patterns during OND season concur with studies that have reported overestimations of OND, also referred as 'short rains' over the study region (Shongwe et al, 2011;Liebmann et al, 2014;Ongoma et al, 2018).…”

“…Further, these studies demonstrate a continued declining annual rainfall trends for different future scenarios over the study domain (Rowell et al, 2015;Tierney et al, 2015;Ongoma et al, 2018). On the contrary, the observed increment patterns during OND season concur with studies that have reported overestimations of OND, also referred as 'short rains' over the study region (Shongwe et al, 2011;Liebmann et al, 2014;Ongoma et al, 2018). Yang et al (2015) highlighted the aspect of challenges associated with simulations of atmosphere-oceanmonsoon interaction over East Africa region as the major cause of observed bias in models during OND and MAM projections.…”

Characterization of Historical Trends of Droughts and Pluvial Scenarios over Kenya, East Africa

“…Furthermore, approximately 450,000 deaths were reported in Ethiopia during the [1984][1985] drought while Kenya witnessed a wide spread drought in 2005, affecting 2.5 million people in the northern region [32,34]. This trend is likely to increase with intensification of extreme climate events towards the end of the 21st century [13,35,36]. Moreover, global predictions based on Palmer Drought Severity Index (PDSI) shows that desiccation will become more severe and widespread over EA region with reduced precipitation and increased evaporation [13].…”