High-impact river floods are often caused by extreme precipitation. Flood protection relies on reliable estimates of the return values. Observational time series are too short for a precise calculation. Here, 100-year return values of daily precipitation are estimated on a global grid based on a large set of model-generated precipitation events from ensemble weather prediction. The statistical uncertainties in the return values can be substantially reduced compared to observational estimates.

Hydrological hazards affect people and ecosystems, but extremes are not fully understood due to limited observations. A large climate ensemble and simple hydrological model are used to assess unprecedented but plausible floods and droughts. The chain gives extreme flows outside the observed range: summer 2022 ~ 28 % lower and autumn 2023 ~ 42 % higher. Spatial dependence and temporal persistence are analysed. Planning for such events could help water supply resilience and flood risk management.

After the 1783 Laki eruption, excess mortality in Iceland was one-sixth of the population, traditionally explained by famine due to livestock loss. Since 1970, it has been suggested that 1) fluorine poisoning may have contributed to mortality in Iceland and 2) air pollution might have caused excess deaths in both Iceland and Europe. Reviewing contemporary Icelandic demographic data, air pollution simulations, and medical records on fluorosis, we show that evidence for both hypotheses is weak.

Extreme rainfall is the leading weather-related source of damages in Europe, but it is still difficult to predict on long timescales. A recent example of this was the devastating floods in the Italian region of Emiglia Romagna in May 2023. We present perspectives based on large-scale dynamical information that allows us to better understand and predict such events.