Fig. 3: Characteristics of Day Zero Drought (DZD) events in terms of waiting time and duration, based on CESM2-LE simulations under the SSP3-7.0 scenario.

The central spatial map shows the spatial distribution of the ensemble-mean waiting time (a) and duration (b) of DZD events, respectively, following the Time of First Emergence (ToFE) at each grid point of DZD-prone regions across the globe. c represents the spatial distribution of the frequency (%) of extreme DZD events, defined as those where the event duration exceeds the waiting time, indicating prolonged water scarcity impact and short recovery period. The accompanying inset circular diagram of c illustrates the distribution of these events, with the color scale indicating the proportion (percentages) of grid cells experiencing such conditions. This visualization highlights where and how frequently extreme DZD conditions with long duration and short waiting time emerge. The surrounding paired panels depict the Probability Density Function (PDF) of waiting time and duration for DZD events across seven DZD-prone regions. Colored lines represent the PDF of each ensemble of 100 CESM2-LE, while the black line is the ensemble mean of the respective PDF. The vertical dashed lines mark the ensemble mean (black), 90th percentile (blue), and 99th percentile (green) for each region. The red dashed line represents the monthly scale of the compound extreme event, which is 48 months. The period considered for each grid point started from the month after each decade of their respective ToFE and continued until 2100.