Researchers from the University of Valladolid in Spain traced the roots of the extraordinary hailstorm that struck Girona, a Catalan city, during the summer of 2022. The disaster left a 1.5-year-old girl among its victims and injured 67 people as hailstones measured up to 12 centimeters. The event caused extensive damage, with ice crusts harming hundreds of buildings and vehicles and also taking a toll on crops. The findings were published in the scientific journal Geophysical Research Letters (GRL).
Experts identified abnormally warm sea surface temperatures as a key driver, noting that ocean waters were more than 3 °C hotter than typical seasonal values. This marine heat played a crucial role in energizing the atmosphere and setting the stage for extreme weather.
The research team showed that the atmospheric convective energy reached unprecedented levels in the region. With moisture drawn from the warm ocean, a powerful updraft formed, giving rise to a supercell—a storm cloud characterized by strong, persistent vertical currents that can sustain severe hail and fierce winds.
To deepen their analysis, scientists compiled a dataset of more than 280 documented supercells spanning from 2011 to 2022. This broad record helped them compare the 2022 Girona event with other extreme hail episodes and to understand the conditions that make such storms more likely.
The researchers concluded that climate warming not only lined up the conditions for Spain’s largest hail event on record but also increased the likelihood of similar disasters in the future. The study emphasizes how rising temperatures at the surface and in the lower atmosphere translate into more intense convective storms capable of producing large hail and substantial damage.
Forecasters and scientists have long noted shifts in the climate system that influence stratospheric and tropospheric dynamics. The Girona hailstorm is presented as a clear example of how elevated ocean temperatures and atmospheric energy interact to generate extreme weather, underscoring the need for ongoing monitoring and improved predictive models to reduce risk and inform preparedness plans. [Geophysical Research Letters]