Every individual possesses a narrative regarding severe weather events, encompassing instances of narrowly avoiding torrential downpours or enduring hailstorms that render vehicles irreparable.
Despite their relative infrequency, hailstorms are responsible for considerable destruction.
Two recent scientific investigations offer insights into the potential transformations of hail phenomena in response to global warming.
Within our investigation, which was disseminated today in the esteemed journal Nature Climate Change, we elucidate that conditions conducive to hail formation may migrate towards the planet’s poles as the Earth’s temperature escalates, and potentially shift away from summer towards winter seasonality.
These climatic shifts could precipitate an increase in hailstorms across regions such as Northern Europe, Canada, the southeastern expanse of Australia, and New Zealand’s South Island.
Concurrently, another groundbreaking study, spearheaded by Shiyi Zhang at Peking University, indicates that hail might also evolve to become more destructive.
Hail events incur substantial financial burdens.
In Australia during 2025, hailstorms that affected New South Wales and Queensland resulted in AU$1.9 billion in insurance claims. Furthermore, in recent years, severe storms have generated immense economic losses worldwide.
The economic impact of severe weather events is on an upward trajectory. A significant factor contributing to this rise is the increasing vulnerability of populations and infrastructure to storms, driven by population growth and urban expansion.
However, a pertinent question arises: is climate change also a contributing factor?
The genesis of hail requires a thunderstorm, which in turn necessitates an updraft.
Updrafts are formed by the ascent of buoyant air within a localized area. This rising air carries water vapor, which subsequently condenses to form clouds composed of minute water droplets.
Within the confines of a storm, these droplets collide. If temperatures are sufficiently low, liquid water droplets can freeze onto ice particles, progressively enlarging them into hailstones.
For hailstones to pose a threat at ground level, a robust updraft must sustain them in the atmosphere long enough for significant growth, and these hailstones must subsequently withstand melting as they descend toward the Earth’s surface.
Wind shear, defined as variations in wind speed and direction with altitude, augments storm intensity by displacing falling rain and hail from the updraft, thereby preventing inhibition and enabling the updraft to intensify.
Buoyancy and wind shear collectively constitute the fundamental atmospheric “ingredients” essential for hail formation.
How might anthropogenic climate change influence hailstorms?
Global warming is leading to a warmer atmosphere and an increase in atmospheric moisture. This moisture serves as the primary fuel for storm development, and a warmer atmosphere is more conducive to generating powerful updrafts capable of supporting larger hailstones.
Conversely, a warmer atmosphere also accelerates the melting of falling hailstones, which could potentially result in smaller hail or complete dissolution before reaching the ground. Consequently, these two opposing effects are at play.
Based on prior research, the prevailing expectation regarding the impact of climate change on hail is a reduction in frequency, but with larger hailstones when events do occur. This hypothesis is predicated on the notion that increased melting would lead to smaller hail reaching the ground less often, while more potent updrafts would facilitate the formation of larger hailstones.
Nevertheless, these climatic alterations exhibit regional variability, contingent upon the intricate equilibrium between the modified hailstorm ingredients.
Global climate models typically lack the resolution to delineate individual storm events, let alone specific hailstones—akin to viewing a low-resolution image that captures the broad outlines but omits fine details.
Therefore, rather than directly analyzing hail, our study focused on examining the alterations in the constituent elements of hailstorms.
Given the persistent uncertainty surrounding the precise interrelationships between these elements and the propensity for hail, we employed several established “proxy” relationships, including one that we previously formulated for Australia, accounting for the diverse weather regimes present in that continent.
We applied three distinct proxies to the output data from eight climate models to explore a spectrum of plausible future warming scenarios.
Firstly, the proxies and models concur that under warming scenarios, hail-conducive conditions are migrating towards the poles—experiencing a decline in mid-latitudes of the Southern Hemisphere, and an increase in mid-to-high latitudes, particularly in the Northern Hemisphere.
Our projections indicate a greater frequency of hail-prone conditions in Northern Europe, Canada, the northwestern United States, southeastern Australia, and the South Island of New Zealand. Conversely, we anticipate a diminished frequency of hail-prone conditions in Northern Australia, much of Africa, Southern India, and southeastern China.
Secondly, our findings indicate a decrease in hail-prone conditions during summer months and an increase during winter.
This suggests that winter cereal crops, such as wheat, may face escalating risks, while the risk could diminish for summer crops like maize. Should climate change precipitate a migration of arable regions towards the poles, these crops may subsequently be exposed to heightened hail frequency in those newly established zones.
Thirdly, the various proxies do not consistently align, particularly within tropical regions, where some indicate an increase and others a decrease in hail risk.
These discrepancies underscore the inherent complexities in quantifying changes within hail environments and their direct correlation to the occurrence of hail events.
What are the implications for the severity of hail when it does manifest?
Zhang and his collaborators adopted a methodology distinct from ours. They applied a sophisticated model simulating hailstone formation and melting to climate projections, with the objective of assessing potential hail sizes and the resultant changes in potential damage.
Their novel global simulations generally forecast an increase in large hailstones and a decrease in smaller ones.
This outcome aligns with previous theoretical considerations – a warmer atmosphere has the capacity to melt smaller hailstones more readily while fostering the development of larger hail through more vigorous updrafts.
Echoing our findings, their study also reveals regional disparities in these projected changes.
Both investigations point towards an escalating risk of hail damage coupled with an increased frequency and potential for severe hail in the mid-to-high latitude regions of the Northern Hemisphere and southeastern South America.
In the subtropical zones of Africa and Northern South America, both studies foresee a reduction in hail risk.
Within the southeastern United States, mid-northern Africa, southern India, and northeastern Australia, our projections indicate a decrease in frequency, whereas Zhang and his colleagues anticipate an increase in damage potential.
These two scientific endeavors collectively suggest an intensification of risk from hail damage in a warming global climate, notwithstanding the ongoing ambiguity concerning the precise geographical distribution of these impacts.
The magnitude of this escalating risk is directly proportional to the extent of global warming experienced.
Swift and decisive reduction of greenhouse gas emissions represents the most efficacious strategy for mitigating the most detrimental consequences of climate change.
