Flash droughts arrive suddenly, within weeks, hitting communities that are often not prepared and causing lasting impact. They are an emerging concern for water and food security. The new study is the first to apply a systematic, quantitative approach to the global incidence of flash drought, mapping hotspots and regions of rapid increases in recent decades.
The study defined and tracked three critical measures of drought severity: speed of onset, duration and geographic extent. It analyzed 40 years of NASA's MERRA-2 climate data, from 1980 to 2019, drawn from weather observations, satellite imagery and modeled root-zone soil moisture, with the aim of improving prediction and disaster preparedness.
Land cover is also important to flash drought vulnerability. Savanna and grasslands are more susceptible to flash droughts than other ecotypes, particularly in humid and semi-humid climates, the study found.