Constraining Flash Drought Projections Through Land-Atmosphere Coupling

The increasing drought onset speed is driving a global transition toward more frequent flash droughts, presenting unprecedented challenges for drought management and adaptation. However, projected changes in future flash drought characteristics show considerable divergence among climate models. Here, using models from the Coupled Model Intercomparison Project Phase 6 (CMIP6), we demonstrate that models capable of capturing the land-atmosphere coupling gradient between dry and wet soil conditions tend to project more pronounced global transition from slow to flash droughts in the future. This emergent relationship provides a robust constraint for future projections based on observed land-atmosphere coupling characteristics. Our analysis suggests that the societal and environmental risks posed by future flash droughts could be more severe than previously projected. Given the widespread impacts of flash droughts, this study not only enhances our understanding of uncertainties in drought projections, but also holds promise for supporting socio-economic planning and adaptation strategies through constrained projection.