Global Projections of Flash Drought in a Warming Climate

<p>As global population continues to rise, the associated demand for agriculture is expected to significantly increase over the next several decades. Furthermore, projected increases in climate variability due to global climate change will impact the cropland expansion and agricultural intensification required to meet the demand in the coming decades. Flash drought presents a unique challenge within the realm of weather and climate extremes. Given their rapid development, drought mitigation strategies are challenging to implement during flash drought because these events often develop with limited warning, while leading to wide-ranging impacts across the land surface. As such, this study seeks to address two key questions on flash drought: 1) What are the trends in flash drought frequency across the globe in a warming climate and 2) how does the risk to cropland from flash drought change in the future? These questions are addressed by identifying flash drought events from six CMIP6 models using the standardized evaporative stress ratio (SESR) and soil moisture. Historical simulations capture the period spanning 1850-2014, while three scenarios are used to project flash drought development under different socioeconomic pathways and radiative forcing levels for the years 2015-2100 (SSP126, SSP245, and SSP585). We find that flash drought occurrence is expected to increase globally among all scenarios, with the sharpest increases seen in scenarios with higher radiative forcing and greater fossil fuel usage. Regionally, the largest projected increases in flash drought occurrence are in Europe and the Amazon. Flash drought risk over cropland is expected to increase globally, with the largest increases projected across North America (change in annual risk from 32% in 2015 to 49% in 2100) and Europe (32% to 53%) in the most extreme SSP585 scenario. Following conservative and medium scenarios compared to high end scenarios indicates a notable reduction in annual flash drought risk over cropland.</p>