Hailstones the size of golfballs are increasingly raining down on Europe as the climate warms, causing expensive damage to cars and buildings.
Very large hail, classified as hailstones that measure 5 centimetres or more in diameter, is one of the most costly forms of extreme weather, capable of smashing windows, denting cars and blowing holes through the roof of a building. 鈥淪ome of the largest loss events, in excess of $1 billion, have been associated with hailstorms that have this type of very large hail,鈥� says at the University of Albany in New York state.
Such hail is triggered by severe thunderstorms and is most commonly experienced in the Great Plains of the US and in South America, particularly in northern Argentina. But as the climate warms, new parts of the world are becoming vulnerable.
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To investigate, at the European Severe Storms Laboratory (ESSL) in Germany and his colleagues used a statistical model to generate a global database of very large hail events from 1950 to 2023. The team found that the frequency of such events has generally decreased in the southern hemisphere and increased in the northern hemisphere. Mendoza in Argentina, for example, which has previously been a very large hail hotspot, has experienced below-average numbers of these events since 2006, with the exception of 2015 and 2016.
In Europe, by contrast, the frequency of very large hail events has increased significantly in recent years. Northern Italy has endured the largest global increase, with a record number of hail reports in Italy between 2021 and 2023. In July 2023, a hailstone with a diameter of 19 cm was recorded in the town of Azzano Decimo in northern Italy, close to the global world record for the largest hailstone diameter of 20.3 cm, which was recorded in South Dakota in 2010.
Tang, who was not involved in the ESSL鈥檚 work, warns that changes to Europe鈥檚 climate, including more severe storms that hold more water, are likely to be driving the increasing trend for very large hail across the continent.
And the costs are adding up. In July 2017, Istanbul suffered two storms with very large hailstorms, which caused $300 million in insured losses. 鈥淚t is the size of hail that determines the damage,鈥� says at Newcastle University, UK. His research suggests small hailstones will become rarer across Europe as the climate warms, but that the risk of rare 鈥� but highly damaging 鈥� very large hail may be growing across the continent. 鈥淭his is some concern for the future,鈥� he says.
Even a small increase in the frequency of very large hail events could cause a sharp uptick in damages, without the introduction of protective measures such as parking cars in garages or under carports, or using more resilient building materials. Such measures can 鈥渕ake a massive difference鈥� to how vulnerable a city is to large hailstones, says Tang.
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