Estimations of potential evapotranspiration from CMIP6 multi-model ensemble over Africa

Potential evapotranspiration (PET) plays a pivotal role in resource management and drought assessment. However, future PET estimates remain underexplored in the African region. This study employs twenty General Circulation Models (GCMs) to estimate past (1979-2014) and future PET changes across near -term (2021-2040), mid-term (2061-2080), and long-term (2081-2100) periods, considering four Shared Socioeconomic Pathways (SSPs) including SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5. The research assesses the impact of various climatic factors on PET across Africa and its sub -regions using the Penman -Monteith model. The analysis reveals that Penman -Monteith estimates for PET during 1979-2014 exhibit an increase of 0.68 mm per year (mm/a) across Africa. Notably, the Northern region (NAF), Sahara (SAH), Southern region (SAF), and Eastern region (EAF) experience higher PET changes of 1.78 mm/a, 1.75 mm/a, 1.09 mm/a, and 0.12 mm/a, respectively. Conversely, the Western region (WAF) and Central region (CAF) exhibit negative trends of -0.03 mm/a, and0.28 mm/a. Future PET in whole Africa is projected to increase by 0.05 mm/a in SSP1-2.6 and SSP2-4.5, and 0.07 mm/a in higher emissions for 2021-2040, by 0.02 mm/an under SSP1-2.6, 0.07 in SSP2-4.5, 0.09 mm/a, and 0.16 mm/a, in SSP3-7.0 and SSP5-8.5 for 2061-2080, and by -0.01 mm/a in SSP1-2.6, 0.05 mm/a SSP2-4.5, 0.10 mm/a SSP3-7.0, and 0.18 mm/a SSP5-8.5 for 2081-2100. Furthermore, higher emissions are anticipated to drive PET increases in various regions during 2081-2100, with NAF, SAH, and SAF projected to rise by 0.17 mm/a, 0.16 mm/a, and 0.23 mm/a, respectively. WAF, CAF, and EAF are expected to experience increases of 0.20 mm/a, 0.19 mm/a, and 0.15 mm/a, respectively. Contribution analysis indicates that solar radiation played a major factor in PET over Africa as well as in WAF, CAF, and EAF. Maximum temperatures were pivotal in NAF, SAH, and SAF. In future periods (2021-2040, 2061-2080, and 2081-2100), maximum temperatures take precedence to Africa's PET, and at varying percentages to different sub -regions. The findings underscore the significance of PET estimation, particularly in the context of drought evaluation locally and regionally.