Increasing frequency and intensity of single, multiple and concurrent meteorological hazards in Europe from a high-resolution dataset (1961–2020)

Abstract By means of a very high (1.5 km) resolution dataset for Europe, we investigate the change between past (1961–1990) and present (1991–2020) periods in the frequency and intensity of meteorological hazards, namely hot (H) and cold (C) waves, droughts (dry (D)), extreme precipitation (wet (W)) and fire weather (F). We analyse not only the changes in hazards taken separately but also the combination of multiple (i.e. two or more hazards happening in the same month but not necessarily in the same year) and concurrent (i.e. happening in the same month and year) events. Europe has become prone to more frequent and intense multiple hazards; in particular, most (>75%) of the land has been subject to increased frequency and intensity of at least two hazards for most of the year, especially H D, H W and H D W combinations. Around 10% of land was subject to an increase in both frequency and intensity of four hazards (H C D W), especially in spring and autumn. Concurrent events have also become more frequent; in particular, the number of concurrent H D events has increased over most of Europe throughout the year, while the number of H F and H D F events has increased over the Mediterranean. Concurrent H W conditions have become more frequent, especially over northeastern Europe and the United Kingdom for most of the year. This led to the population cumulatively exposed to concurrent H D events in 1991–2020 being around 2.7 times larger than in 1961–1990 in November and 4.7 times larger in August, while that exposed to H W conditions in May in 1991–2020 was 7.3 times larger than in 1961–1990. These results highlight the increasing risk of multiple and concurrent extreme events, and advocate for preparedness and adequate adaptation strategies.