Climate change could make hail more destructive in some areas while mitigating risks in others.
On April 28, a severe hailstorm hit Springfield, Missouri, dropping chunks of ice the size of baseballs, some even larger than grapefruits. The giant hail smashed cars, destroyed homes and injured people and animals.
This type of destructive hail is increasingly making headlines. In a warming world, ice falling from the sky seems more likely to melt. But hailstones could instead become larger and more destructive in many regions of the worldalthough risks vary by region, researchers report May 27 in Nature.
“The study makes an interesting and timely contribution to understanding the impact of climate change on hail risks,” says climatologist Davide Faranda of the National Center for Scientific Research in Paris. “It combines physical reasoning with climate model projections.”
Hail forms when strong storm winds lift moisture into cold clouds. There, water droplets freeze around tiny particles and grow until they become too heavy for the winds to handle. To see how hailstones might change in a warmer world, researchers at Peking University built a computer simulation that estimates how hailstones grow inside clouds based on atmospheric conditions, such as temperature, humidity and wind. The team tested the computer model on more than 14,000 real hailstorms around the world between 2014 and 2021, then used it to explore how these storms would evolve under future climate conditions.
Large hailstones are expected to become more frequent, making hailstorms more damaging, the model suggests. This trend reflects two competing effects. Warmer air can hold more water vapor, giving hailstones more material to grow. At the same time, as the atmosphere warms, hailstones pass through a deeper layer of air that is hot enough to melt them before hitting the ground.
“Large hailstones also melt, but they can still reach the ground as large pieces of ice,” says Qinghong Zhang, a meteorologist at Peking University who led the research. “Smaller hailstones are affected more. They can melt completely and turn into raindrops.”
The danger, the team found, is not the same everywhere. Regions farther from the equator could be hit harder, while hail damage in tropical and subtropical regions could actually lessen. This is partly because by the end of this century, temperatures are expected to rise more sharply at higher latitudes. The additional warming can strengthen updrafts inside storm clouds, allowing hailstones to grow larger, says meteorologist Shiyi Zhang, also of Peking University.
“This is the first study to carry out a quantitative estimation of global hail risks,” Qinghong Zhang said. The overall conclusion is plausible and consistent with previous work, Faranda says. But he is less sure of the quantitative results and regional forecasts. “Hail is an extremely local phenomenon,” he explains. “Global climate models cannot explicitly resolve hailstorms. » This means that studies based on broader weather models always have uncertainties.
Qinghong Zhang acknowledges these uncertainties. Still, she said, the team tested its results against hailstorms recorded over the past decades in China and the United States. These controls suggest that the uncertainties are manageable.
For now, the study sends a clear warning: If temperatures continue to rise, larger, more damaging hail will likely become a greater threat in many areas, Shiyi Zhang says.