Dimitri Defrance , Benjamin Sultan, Mathieu Castet, Adjoua Moise Famien, Camille Noûs, Christian Baron

Food security is a crucial issue in the Sahel and could be endangered by climate change and demographic pressure during the 21st century. Indeed, people in rural areas mainly practice rainfed agriculture for subsistence during the monsoon rainfall season. Higher temperatures and changes in rainfall induced by global warming are threatening food production systems in this region while the population of this region is expected to increase approximately threefold until 2050 according to several demographic scenarios. However climate change is very uncertain, with monsoon rainfall that might either increase or decrease, according to different climate models and greenhouse gases emissions scenarios.
Our study quantifies the impact of climate change on food security by combining climate, crops yield and demographic evolution. Using 16 global climate models, we investigate the evolution of solar radiation, temperature and precipitation under two future climatic scenarios. We simulate yield for the main crops in West-Africa: maize, sorghum and millet. Finally, we estimate in terms of production in the future and is scaled by population changes in order to assess the number of available cereal production per capita in five countries in West Africa.
We found that, although uncertain, the evolution of the African monsoon is different between the countries with a rainfall increase in the Eastern Sahel for Niger and Nigeria and a decrease in the Western Sahel for Senegal under the Representative Concentration Pathway 8.5 scenario. With regard to the abundance of food for the inhabitants, all the scenarios in each country show that in 2050, local agricultural production will be below than 50 kilograms per capita, which corresponds to the basic threshold for feeding all the inhabitants of West Africa. The prospects for improving or adapting current agronomic techniques and/or expanding the cultivated areas do not allow to reach this threshold even by taking into account the [CO2] effect, which has a positive effect in drought situations. This would place additional pressures on resources in the region, with potentially strong impacts on crops import and regional migration.