Efficient agricultural practices in Africa reduce crop water footprint despite climate change, but rely on blue water resources

Alarming projections of climate change, decline in crop yields, and increased food demand constitute daunting threats to African food production and sustainable water management. Here, we map this complex water-food nexus by combining gridded climate data and process-based crop modelling to quantify scenarios of crop water footprint under Representative Concentration Pathway 2.6 and Representative Concentration Pathway 6.0 for time horizons 2040, 2070 and 2100. We show that high-input agricultural management coupled with the expansion of irrigation infrastructure could generate an average reduction of water use intensity up to 64% for staple crops, but only 5% for cash crops, by 2040. Notwithstanding the positive effect of intensification, between 82 Km3 (2040) and 102 Km3 (2100) of additional blue water will be required to sustain the increased yields. Our scenarios are suited for identifying locations where crops are subject to high climate impacts and where crop production shows trade-offs between high-input management and irrigation demand. Efficient agricultural management and irrigation infrastructure expansion, could reduce crop water footprint by 2040 in Africa, but more blue water would be needed after 2040 to maintain increasing yields, according to model projections of water footprint for the 21st century