Drought impact assessments for crop production need to be crop-specific

By an additional 83 million people to the world’s population every day, the global population is expected to reach about 9.8 billion by 2050. Feeding these billions is one of the challenges of this century, and extreme events like droughts bring more complexity to the challenge of global food security. Previous agricultural drought studies on the regional or national scale revealed that drought affects specific crops differently; however, these studies are limited to a few major crops or specific regions. Here we analyse for the first time, to our knowledge, crop responses to drought for 25 rainfed crops on a global scale and differentiate crop responses to aridity and drought for thirty years (1986-2016). We use actual and potential crop evapotranspiration calculated by the Global Crop Water Model (GCWM) and develop the two indicators of Crop Drought Index (CDI) and Aridity Index (AI) to investigate the effect of water stress on crop production worldwide. We show crops’ behaviours in extreme drought events differ in time and space. Years with the most severe drought events also differed for the specific crops. To interpret the impacts of drought and aridity on individual crops in specific locations, and avoid any misperception on their potential damages, we map crop-specific AI and crop-specific CDI of all 25 crops during the study period. We compare the spatio-temporal variation of CDI against a global map of AI for each crop to reflect different impacts of long-term water stress experience (aridity) against extreme events (drought). We learn different crops have different responses to aridity and drought. Our findings are of critical importance for drought-resilient agricultural plans and may help to guide the implementation of food security and food aid strategies.