These examples are part of the publication
Keune, J., Di Giuseppe, F., Barnard, C., Damasio da Costa, E. and Wetterhall, F.: ERA5–Drought: Global drought indices based on ECMWF reanalysis. Scientific Data 12, 616 (2025). https://doi.org/10.1038/s41597-025-04896-y
The ERA5–Drought dataset offers insights for a range of applications. For example, users can analyse time series of drought occurrence and severity for specific locations or undertake more intricate analyses, such as exploring the impact of drought on regions and local communities. In the examples that follow, we demonstrate how such tasks can be accomplished with ease using the ERA5–Drought dataset. To do so, we focus on two additional drought-affected regions: Catalonia (Spain) and Kenya.
Climatology of annual drought events over Catalonia, Spain.
(a) Time series of the area of Catalonia in moderate/severe/extreme drought (in %, indicated in light/medium/dark brown colours) based on the SPEI-12 for each calendar year between 1940–2023 using the ERA5–Drought dataset.
(b–e) Maps of four of the most extensive annual drought events over Catalonia, i.e., 1945, 1950, 2017, 2023. Near-normal values are masked white.
The figure above shows a time series and maps of annual drought events over Catalonia from 1940–2023. The time series shows the area experiencing moderate/severe/extreme drought using the SPEI for each calendar year available from the record; colors indicate the intensity of the drought. The recent drought event in 2023 stands out as one of the most extreme annual droughts: around 82% of the region is in drought conditions (see dark-, medium- and light brown bars ). Moreover, around 50% of the region is experiencing extreme drought conditions at the end of 2023. However, a few more years stand out and indicate similar drought conditions: 1945, 1950, and 2017. In all cases, more than 80% of the region experiences dry anomalies, although the spatial patterns vary (see panels b–e). In addition, the multi-annual drought event in 2004–2007 stands out.
Prolonged droughts can have far-reaching impacts that affect society. Especially highly-vulnerable societies are predicted to experience more frequent and more intense water shortages induced by drought. These water shortages do not only affect the availability of drinking water but can further cause crop failure and food insecurity and, in the worst case, induce famine and cause deaths. Here, we associate registered water- and food insecurity events with the occurrence and intensity of meteorological droughts to illustrate the usability of this data set beyond environmental science. To do so, we use impact data from the Emergency Events Database (EM-DAT, Delforge et al., 2023), which records the occurrence of natural disaster worldwide and compiles their socio-economic impacts from reports and articles published by press agencies, UN-, non-governmental, and other research organizations, among others. Drought events in EM-DAT are registered if 10 or more fatalities were reported, 100 or more people were affected, a state of emergency was declared, or a call for international assistance was issued.
Droughts and their impacts in Kenya.
Time series of the area of Kenya in drought (brown bars, same as previous figure but using the SPI-12 for each calendar year) based on ERA5–Drought, and related impacts (orange symbols and orange bars) based on EM-DAT registered drought events.
Symbols indicate associated disasters at the country level, i.e., food shortage, crop failure & food shortage, and famine. EM-DAT events of unknown start date and end date are plotted over the full event years; symbols in the center of the event. Data is restricted to 1960--2023 due to the availability of EM-DAT data.
While the database is constantly growing, it is not considered to be exhaustive — yet, it enables us to estimate the impact of droughts on society. Here, we focus on Kenya and demonstrate the co-occurrence of meteorological drought, expressed as the SPI-12, with food insecurity as reported in EM-DAT. Figure above shows the area of Kenya affected by droughts as brown bars, the registered impacts as orange symbols (i.e., famine, crop failure & food shortage, and food shortage as orange triangles, stars, and circles, respectively) and the number of people affected as orange bars. This analysis shows that all reported impacts occurred during or shortly after meteorological droughts. During the multi-annual drought in 2000–2001, for example, up to 35% of the country experienced severe to extreme precipitation deficits, affecting more than 1 million people up until 2003 and ultimately contributing to food shortage and deaths associated with the drought impacts. In addition, the repercussions of this multi-annual drought event and additional consecutive, years with (slightly) less than normal rainfall may have further contributed to the famines reported in 2007 and 2011. The recent drought over Kenyain 2021–2022/2023 shows the largest precipitation deficits recorded since 1960: around 35% of the country suffered extreme drought conditions in 2021, and precipitation continued in 2022, resulting in 70% of the country being affected by drought by the end of 2022 and beyond. While food shortages have already been registered in EM-DAT as an impact of the recent drought, the total impacts of this drought may extend beyond what has been recorded so far.