Future crop water footprint scenarios across the African continent - Assessing the impacts of climate change and advanced management strategies on agriculture, production and water resources

Alarming projections of climate change, increasing aridity and decreasing water availability, coupled with continued population growth, changes in dietary patterns and expanding biofuel use represent some of the heaviest pressures on global agriculture. In addition, crop yields are generally projected to decrease under future climate conditions. All these factors heavily impact food production and constitute worrisome implications for food security. At the same time, to meet the projected demands from population and societal changes, global crop production needs to double globally by 2050, and the commonly preferred solution for achieving such increment is through boosting crop yields. But while western countries are closer to their crop yield potential, Africa still falls behind in crop yield gap closure. This work develops high-resolution, Water footprint (WF) scenarios of different crops across the African continent for 2010, 2040, 2070 and 2100, in order to assess the impacts of climate change on African agriculture. In addition, by including crop yield forecasts which project a high input, advanced management agriculture on the continent, it investigates if food security can be achieved by increasing production on the current harvested areas and how this will affect the water resources. Results show that advanced management practices bring crop yields to increase up to three folds, while the water use efficiency also improves - between 2010 and 2040, the average unitary WF decreases by 62% and 74%, in the case of maize and sorghum respectively, over the whole continent. As an example, in Mozambique it decreases by 78% between 2010 and 2040; nevertheless, in Egypt the unitary WF increases by 58%, in the case of maize. At the same time, in both countries, the total water use for maize increases from 2010 to 2040, respectively by 58% and 150%. These results show that, when the increment in agricultural production is taken into account, the total water volume needed rises - 30% and 25% average increment in volume, respectively for maize and sorghum, between 2010 and 2040 across Africa -, putting a strain on a natural resource already affected by climate change.