Global Patterns and Ecological Effects of Drought Intensification: A Multiscale Analysis

Abstract

This study delineates the criteria for identifying different types of droughts based on root zone soil moisture deficits, categorizing them into sudden, general, and creeping droughts. By employing an adapted version of the drought detection method proposed by Yuan et al., drought events were analyzed across 26 IPCC-SREX regions using historical soil moisture data. Our findings demonstrate that sudden droughts, which entail a rapid decline in soil moisture, predominantly occur in climatic hotspots and have shown an increasing trend over the past four decades, particularly in Central Europe and South Asia. The research also explores the seasonality of droughts, noting that flash droughts typically align with the growing season, while creep droughts often commence later in the year, potentially affecting vegetation growth in subsequent seasons. The ecological impact assessment, based on the Normalized Difference Vegetation Index (NDVI), reveals a lag in vegetation response to rapid water stress, with a marked decline in health by the end of the drought onset phase. These results underscore the varying ecological responses to drought intensification and contribute to a better understanding of their global patterns and impacts.