Anthropogenic Mediterranean warming essential driver for present and future Sahel rainfall

The long-lasting Sahel drought in the 1970s and 1980s caused enormous human and socio-economic losses, driving extensive research on its causes. Although changes in global and regional sea surface temperatures (SSTs) are thought to be dominant drivers of the severe Sahel drying trend, the mechanisms for the recent recovery trend are not fully clear yet, but are often assumed to be akin to the previous SST-Sahel drought linkage. Here we show, by analysing observational and multi-model data and conducting SST-sensitivity experiments with two state-of-the-art atmospheric models, that the SST key area causing the recent Sahel rainfall recovery is the Mediterranean Sea. Anthropogenic warming of this region has driven the shift from the tropical Atlantic and Indo-Pacific oceans, which historically were the main driver of Sahel drought. The wetting impact of Mediterranean Sea warming can become more dominant in a future warming climate and is key to understanding the uncertainty in future Sahel rainfall projections.