Crop yield sensitivity of global major agricultural countries to droughts and the projected changes in the future

Livestock production can have many environmental impacts, one of which is the use of water. When livestock are fed on crops that have been cultivated with irrigation, the water footprint can be staggeringly high. The UN Food and Agriculture Organization estimates about 69% of all water withdrawals worldwide are used for agriculture, and on average 37% of the cereals produced in the world are used for animal feed. However, the environmental impact of water withdrawals for feed crops depends on where and when the water is used. Water withdrawals from places where water use is already unsustainable can be especially harmful, in particular at times of extreme water scarcity i.e. during droughts. Our analysis on the impacts of livestock production on the aquatic environment has begun with in-depth analysis of the places and times when water resources for agriculture are most scarce. This paper, published in Science of the Total Environment, sets out our methodology and results for identifying where drought impacts on agriculture are most critical. It paves the way for the next step, which will be to identify hotspots where production of feed crops is most harmful for scarce water resources.

Yield loss risk tends to grow faster when experiencing a shift in drought severity from moderate to severe than that from extreme to the exceptional category, demonstrating the non-linear response of yield to the increase in drought severity. Sensitivity analysis shows that temperature plays an important role in determining drought impacts, through reducing or amplifying drought-driven yield loss risk. Compared to present conditions, an ensemble of 11 crop models simulated an increase in yield loss risk by 9%–12%, 5.6%–6.3%, 18.1%–19.4% and 15.1%–16.1 for wheat, maize, rice and soybeans by the end of 21st century, respectively, without considering the benefits of CO₂ fertilization and adaptations. This study highlights the non-linear response of yield loss risk to the increase in drought severity. This implies that adaptations should be more targeted, considering not only the crop type and region but also the specific drought severity of interest.