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

===== 9.5.3.2.1 Observations =====

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Negative trends in rainfall accompanied by increased rainfall variability were observed between 1960s–1980s over west Africa ( [[#Nicholson--2018|Nicholson et al., 2018]] ; [[#Thomas--2018|Thomas and Nigam, 2018]] ), caused by a combination of anthropogenic aerosols and GHGs emitted between the 1950s and1980s ( [[#Booth--2012|Booth et al., 2012]] ; [[#Wang--2016|Wang et al., 2016]] ; [[#Giannini--2019|Giannini and Kaplan, 2019]] ; [[#Douville--2021|Douville et al., 2021]] ). Declining rainfall trends ended by 1990 due to the growing influence of GHGs and reduced cooling effect of aerosol emissions, with a trend to wetter conditions emerging in the mid-1990s accompanied by more intense, but fewer precipitation events ( [[#Sanogo--2015|Sanogo et al., 2015]] ; [[#Sylla--2016|Sylla et al., 2016]] ; [[#Kennedy--2017|Kennedy et al., 2017]] ; [[#Barry--2018|Barry et al., 2018]] ; [[#Bichet--2018a|Bichet and Diedhiou, 2018a]] ; 2018b; [[#Thomas--2018|Thomas and Nigam, 2018]] ). A shift to a later onset and end of the west African monsoon is also reported in west Africa and Sahel ( ''low confidence'' ) ( [[#Chen--2021|Chen et al., 2021]] ; [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ). Between 1981–2014 the Gulf of Guinea and the Sahel have experienced more intense precipitation events ( [[#Panthou--2014|Panthou et al., 2014]] ; [[#Bichet--2018a|Bichet and Diedhiou, 2018a]] ; [[#Panthou--2018|Panthou et al., 2018]] ) and the frequency of mesoscale storms has tripled ( [[#Taylor--2017|Taylor et al., 2017]] ; [[#Callo-Concha--2018|Callo-Concha, 2018]] ). Extreme heavy precipitation indices show increasing trends from 1981–2010 ( [[#Barry--2018|Barry et al., 2018]] ), increasing high flow events in large Sahelian rivers as well as small to mesoscale catchments leading to pluvial and riverine flooding ( [[#Douville--2021|Douville et al., 2021]] ). Meteorological, agricultural and hydrological drought in the region has increased in frequency since the 1950s ( ''medium confidence'' ) ( [[#Seneviratne--2021|Seneviratne et al., 2021]] ).

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