Changes in the severity of compound hot-dry-windy events over global land areas

Abstract

Hot-dry-windy events (HDWEs), characterized by concurrent high temperature, low humidity, and strong wind speeds, are associated with reduced crop yields, accelerated spread of wildfire, increased human health risks, and dust storms across various regions. A comprehensive understanding of global HDWE severity is crucial for mitigating these detrimental consequences. However, current assessments of HDWE show notable regional constraints due to the lack of a universal definition for its severity. In this study, we introduce a standardized hot-dry-windy index (SHDWI) using multi-source datasets to assess spatial and temporal changes in the severity of HDWEs across the globe. Influenced by significantly rising temperatures, intensified wind speeds, and declining humidity, a notable decreasing trend (-0.09/decade, p < 0.01) in SHDWI indicates a rise in warm-season HDWE severity on average across the global land areas, particularly in South America, North Africa, western Europe, and southeastern Asia. Geospatially, Europe, Africa, South America, and Asia have experienced substantial increases in HDWE severity and expanded areas affected by strong HDWEs between 1980–1998 and 1999–2017. Notably, HDWE severity is predominated by temperature in the south of 30°N but by humidity in the north of 30°N. The standardized index proposed in this study would be beneficial for a worldwide assessment of future HDWE risks under climate change.