Storylines of Sahel precipitation change: roles of the North Atlantic
and Euro-Mediterranean temperature
Abstract
Future changes in Sahel precipitation are uncertain because of large
differences among projections from various models. In order to explore
this uncertainty, we use a storyline approach which seeks to identify
alternative plausible evolutions of Sahel precipitation and their
driving factors. By analysing projections from the CMIP6 climate models,
we show that changes in North Atlantic and in Euro-Mediterranean
temperatures explain up to 50% of the central Sahel precipitation
change uncertainty. We then construct several storylines of Sahel
precipitation change based on future plausible changes in North Atlantic
and Euro-Mediterranean temperatures. In one storyline, an amplified
warming of both the North Atlantic and the Euro-Mediterranean areas
promotes a northward shift of the West African monsoon, increasing
precipitation over the central Sahel, while, in another storyline, a
moderate warming in both regions is associated with a small change in
precipitation over the central Sahel and a decrease in precipitation
over the western Sahel, at the end of the 21st century. These results
indicate that reducing uncertainty in future changes in Sahel
precipitation could be achieved by reducing uncertainty in the future
warming of the North Atlantic and the Euro-Mediterranean areas.