Negative trends in rainfall accompanied by increased rainfall variability were observed between 1960s-1980s over west Africa , caused by a combination of anthropogenic aerosols and GHGs emitted between the 1950s and1980s . 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 . A shift to a later onset and end of the west African monsoon is also reported in west Africa and Sahel  . Between 1981-2014
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