Editing IPCC:AR6/WGII/Chapter-9 (section)

=== 9.5.4 Central Africa ===

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==== 9.5.4.1 Temperature ====

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===== 9.5.4.1.1 Observations =====

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Mean annual temperature across central Africa has increased by 0.75°C–1.2°C since 1960 ( [[#Aloysius--2016|Aloysius et al., 2016]] ; [[#Gutiérrez--2021|Gutiérrez et al., 2021]] ). The number of hot days, heatwaves and heatwave days increased between 1979–2016 ( [[#Hu--2019|Hu et al., 2019]] ) and cold extremes have decreased (Figure 9.14; [[#Aguilar--2009|Aguilar et al., 2009]] ; [[#Seneviratne--2021|Seneviratne et al., 2021]] ). Uncertainties associated with the poor ground-based observation networks in the region and associated observational uncertainties ( [[#9.5.1.1|Section 9.5.1.1]] ) result in an assessment of ''medium confidence'' in an increase in the number of heat extremes over the region.

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===== 9.5.4.2 Projections =====

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At 1.5°C, 2°C and 3°C of global warming above pre-industrial levels, mean annual temperatures in central Africa are projected to be on average, 0.6°C, 1.1°C and 2.1°C warmer than the 1994–2005 average, respectively (Figure 9.16a). By the end of the century (2070–2099), warming of 2°C (RCP4.5 ) to 4°C (RCP8.5) is projected over the region ( [[#Aloysius--2016|Aloysius et al., 2016]] ; [[#Fotso-Nguemo--2017|Fotso-Nguemo et al., 2017]] ; [[#Diedhiou--2018|Diedhiou et al., 2018]] ; [[#Mba--2018|Mba et al., 2018]] ; [[#Tamoffo--2019|Tamoffo et al., 2019]] ) and the number of days with maximum temperature exceeding 35°C is projected to increase by 150 days or more at GWL 4.4°C ( [[#Gutiérrez--2021|Gutiérrez et al., 2021]] ; [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ). According to CMIP6 and CORDEX (Coordinated Regional Climate Downscaling Experiment) models, the annual average number of days with maximum temperature exceeding 35°C will increase between 14–27 days at GWL 2°C and 33–59 days at GWL 3°C above the 61–63 days for 1995–2014 ( [[#Gutiérrez--2021|Gutiérrez et al., 2021]] ; [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ) ( ''high confidence'' ). The number of heatwave days is projected to increase and extreme heatwave events may last longer than 180 days at GWL 4.1°C ( [[#Dosio--2017|Dosio, 2017]] ; [[#Weber--2018|Weber et al., 2018]] ; [[#Spinoni--2019|Spinoni et al., 2019]] ). Children born in 2020, under a 1.5°C-compatible scenario will be exposed to 6–8 times more heatwaves in their lifetimes compared to people born in 1960; this exposure increases to 7–9 times more heatwaves at GWL 2.4°C ( [[#Thiery--2021|Thiery et al., 2021]] ). The number of potentially lethal heat days per year is projected to increase from &lt;50 during 1995–2005 to 50–75 at GWL 1.6°C, 100–150 at GWL 2.5°C and 200–350 at GWL 4.4°C ( [[#Mora--2017|Mora et al., 2017]] ).

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==== 9.5.4.2 Precipitation ====

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===== 9.5.4.2.1 Observations =====

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The severe lack of station data over the region leads to large uncertainty in the estimation of observed rainfall trends and ''low confidence'' in changes in extreme rainfall (Figure 9.13b; [[#Creese--2018|Creese and Washington, 2018]] ; [[#Gutiérrez--2021|Gutiérrez et al., 2021]] ; [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ). There is some evidence of drying since the mid-20th century through decreased mean rainfall and increased precipitation deficits ( [[#Gutiérrez--2021|Gutiérrez et al., 2021]] ), as well as increases in meteorological, agricultural and ecological drought ( ''medium confidence'' ) ( [[#Seneviratne--2021|Seneviratne et al., 2021]] ). However, there is spatial heterogeneity in annual rainfall trends between 1983–2010 ranging from −10 to +39 mm per year ( [[#Maidment--2015|Maidment et al., 2015]] ), with a decline in mean seasonal April–June precipitation of −69 mm per year in most regions except in the northwest ( [[#Zhou--2014|Zhou et al., 2014]] ; [[#Hua--2016|Hua et al., 2016]] ; [[#Klotter--2018|Klotter et al., 2018]] ; [[#Hu--2019|Hu et al., 2019]] ). Southern and eastern central Africa were identified as drought hotspots between 1991–2010 ( [[#Spinoni--2014|Spinoni et al., 2014]] ).

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===== 9.5.4.2.2 Projections =====

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Under low emission scenarios and at GWL 1.5°C and GWL 2°C there is ''low confidence'' in projected mean rainfall change over the region (Figure 9.16c). At GWL 3°C and GWL 4.4°C, an increased mean annual rainfall of 10–25% is projected by regional climate models ( [[#Coppola--2014|Coppola et al., 2014]] ; [[#Pinto--2015|Pinto et al., 2015]] ) and the intensity of extreme precipitation will increase ( ''high confidence'' ) (Figure 9.16c, d; [[#Sylla--2015a|Sylla et al., 2015a]] ; [[#Diallo--2016|Diallo et al., 2016]] ; [[#Dosio--2019|Dosio et al., 2019]] ; [[#Gutiérrez--2021|Gutiérrez et al., 2021]] ; [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ; [[#Seneviratne--2021|Seneviratne et al., 2021]] ). This is projected to increase the likelihood of widespread flood occurrences before, during and after the mature monsoon season (Figure 9.14).

Convection-permitting simulations (4.5 km spatial resolution) simulate increased dry spell length not apparent at coarser resolutions, suggesting drying in addition to more intense extreme rainfall ( [[#Stratton--2018|Stratton et al., 2018]] ). Although reduced drought frequency is indicated in Figure 9.16e, the SPI metric does not account for the effect of increased temperature on drought (increased moisture deficit), and metrics that account for this indicate slightly increased drought frequency or no change ( [[#Spinoni--2020|Spinoni et al., 2020]] ). Therefore, there is ''low confidence'' in projected changes of drought frequency over the region (Figure 9.14).

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