The effects of climate change on hailstorms

Hailstorms are dangerous and costly phenomena that are expected to change in response to a warming climate. In this Review, we summarize current knowledge of climate change effects on hailstorms. As a result of anthropogenic warming, it is generally anticipated that low-level moisture and convective instability will increase, raising hailstorm likelihood and enabling the formation of larger hailstones; the melting height will rise, enhancing hail melt and increasing the average size of surviving hailstones; and vertical wind shear will decrease overall, with limited influence on the overall hailstorm activity, owing to a predominance of other factors. Given geographic differences and offsetting interactions in these projected environmental changes, there is spatial heterogeneity in hailstorm responses. Observations and modelling lead to the general expectation that hailstorm frequency will increase in Australia and Europe, but decrease in East Asia and North America, while hail severity will increase in most regions. However, these projected changes show marked spatial and temporal variability. Owing to a dearth of long-term observations, as well as incomplete process understanding and limited convection-permitting modelling studies, current and future climate change effects on hailstorms remain highly uncertain. Future studies should focus on detailed processes and account for non-stationarities in proxy relationships. Hailstorms are dangerous phenomena that are expected to change in response to a warming climate. This Review summarizes current knowledge of climate change effects on hailstorms, details the uncertainties and highlights future research directions. Key pointsEfforts to understand the effects of climate change on hail are complicated by the small scale and relative rarity of hailstorms, which make hail hard to observe and model.Climate change affects low-level moisture and convective instability, microphysical processes and vertical wind shear, all of which are relevant to hail formation and properties.A scarcity of hail observations and high-resolution modelling studies, and gaps in the understanding of physical processes, contribute to the current high uncertainty around the effects of climate change on hailstorms worldwide.General indications based on observations and modelling are of overall hailstorm frequency increasing in Australia, slightly increasing in Europe and decreasing in East Asia and the USA.In most regions, hailstorm severit