| Summary: | The West African Monsoon (WAM) brings precipitation in summer for around 80 million people from Senegal to Chad. Variability of the monsoon circulation has large impacts on Sahelian societies. However, future changes in Sahel precipitation are uncertain because of large differences between projections of various climate models. We show that uncertainty in Sahel precipitation change is associated with uncertainty at simulating future changes in surface air temperature over the northern Hemisphere, towards the end of the 21 st century. We use a storyline approach, a statistical method, to construct scenarios of changes in Sahel precipitation, whose differences only depend on effects and uncertainty at simulating selected remote drivers of Sahel precipitation change. We select two remote drivers, the warming of the Atlantic Ocean and of the Euro-Mediterranean area. We show that uncertainty in changes in Atlantic Ocean and Euro-Mediterranean surface air temperature explains up to 50% of Sahel precipitation change uncertainty. We suggest that reducing uncertainty in the future warming of the North Atlantic and the Euro-Mediterranean areas would then allow reducing uncertainty in future changes in Sahel precipitation.
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