Record-breaking European meteorological droughts in 1921-2024

Pan-European summer drought of 2022 affected different sectors as agriculture, energy, ecosystems, and population health, with both large-scale and local remarkable impacts. In the last decades, similar extreme droughts hit Europe, to the point that in some areas as the Mediterranean Region such events are becoming the new normal. This study moves from two questions: can we find comparable events as we move back in time? Has Europe ever experienced a period with more frequent and/or severe droughts? To provide the answers, we constructed a new database of meteorological drought events from 1921 to 2014. As input, we used the E-OBS gridded daily precipitation and temperature data, we computed the Standardized Precipitation Index (SPI) and the Standardized Precipitation-Evapotranspiration Index (SPEI) at multiple accumulation scales, and we set a multi-parameter system (including duration, severity, intensity, extent, and peak) to assign a 0-100 score to droughts at country scale. The single events are therefore classified into five big categories to provide decadal statistics and investigate the trends of mega-droughts over the last one hundred years. For the events occurred after 1950, we also estimated population and land-use exposure. According to our analyses, no other summer drought in 1921-2023 exceeded that of 2022, confirming its exceptional features, in particular regarding intensity and extent. Our findings show that - in the last two decades - the meteorological drought severity actually increased through most of Europe, if compared with the second half of the 20th century. However, they also show that Europe already experienced a period of comparable drought hazard from the late 1930s to the late 1940s, including long multi-country droughts never recorded again. Being aware that high-quality climatic data are sparser as we go backwards in time, the results presented here suggest that recent extreme droughts might not be record-breaking – in particular regarding duration - if we extend the analyses to a hundred years ago.