Impact of flash droughts on global crop yields considering crop phenology and irrigation conditions

Flash droughts are characterized by rapid onset and intensification. Different from slow droughts, flash droughts rapidly reduce soil water content, leaving less time for preparation and mitigation, and have the potential to significantly influence agriculture production and threaten food security. However, assessments of the agricultural impacts of flash droughts, especially flash drought risk at different periods of crop growth and its associated impacts on crop yields, as well as their impacts between rain-fed and irrigated agriculture, and between surface water and groundwater irrigation scheme, are generally lacking. This study conducted comprehensive analysis of the flash drought impacts in global agricultural areas by integrating multiple datasets, including globally crop yields, crop phenology, rain-fed and irrigated systems, and soil moisture data. The results suggested proportion of flash droughts in agricultural areas were increased, along with the accelerated drought onset. In view of crop phenology, the first growing season from the start of season (SOS) to the maximum of season (MOS), in particular, was more vulnerable to flash droughts with more than 50% of flash droughts occuring in this period. The impact of flash droughts on the yield of rain-fed crops was approximately 5%–20% greater than that of irrigated crops. Specifically, rain-fed maize and wheat were mostly affected by medium-duration droughts, rain-fed rice by short-duration droughts, and rain-fed soybean by long-duration droughts. Regarding the irrigation water sources, the groundwater irrigated areas presented higher resilience than surface water irrigated areas in response to flash droughts. The results are promising to enhance the understanding of the flash drought impacts on crop yields, which also have implications for water management, drought adaption and strategies for cultivated areas globally in a warming climate.