Multi-model ensemble projections of soil moisture drought over North Africa and the Sahel region under 1.5, 2, and 3 °C global warming

Abstract : The intensification of soil moisture drought events is an expected consequence of anthropogenic global warming. However, the implication of 1.5-3 °C global warming on these events remains unknown over North Africa and the Sahel region, where soil moisture plays a crucial role in food security that largely depends on rainfed agriculture. Here, using a multi-model ensemble from the Inter-Sectoral Impact Model Intercomparison Project phase 2b, we estimate the changes in the spatiotemporal characteristics of soil moisture drought events under increased global mean temperature. A 3 °C global warming results in multi-year (up to 19 years) mega-drought events over North Africa compared to a maximum drought duration of 12 years under the 1.5 °C Paris Agreement target. These events are projected to transform from historically severe droughts into exceptional droughts and extend over an area that is 32% larger under 3 °C compared to that under 1.5 °C. Global warming also leads to a high intensification of Sahelian drought extremes, in particular, their duration (from 24 to 82 months between 1.5 and 3 °C) over the western parts and their severity everywhere. Even though the results highlight substantial uncertainties arising from climate forcing and impact models, the projections indicate a tendency toward unprecedented exacerbation of soil moisture droughts that could pose serious threats to food security of North African and Sahelian societies in the absence of effective mitigation and adaptation.