Plant and soil characteristics as key predictors for future agricultural drought

Drought is one of the most complex and multidimensional types of extreme events, with meteorological and agricultural droughts being two of the most widely studied types. Here, we analyze agricultural drought with a crop water stress index (CSI) that incorporates plant and soil characteristics and soil moisture. The new index is evaluated against other standardized meteorological drought indices, such as the standardized precipitation index and the standardized soil moisture index. The results show substantial differences between the standardized indices and the CSI. To study future drought patterns, we use multiple future scenarios simulated by the Max Planck Institute Earth System Model. In contrast to the standardized indices, the results of the CSI show an improvement in the future global mean drought conditions due to a greater increase in mean wet than dry conditions governed by soil moisture and precipitation, while both dry and wet extreme conditions increase in intensity. Nonetheless, the results suggest large cropland areas will be subject to intense drought conditions under the Shared Socioeconomic Pathways SSP-1.19 to SSP-5.85. Such drought assessment can only be supported by using more complex drought indices. Our results emphasize the importance of combining plant and soil information with standardized indices in the assessment of drought-driven crop stress under climate change aiding effective policy formulation.