Thunderstorms, hail and tornadoes
Localised but extremely destructive
Losses from thunderstorms are rising
Losses from severe thunderstorms in North America in 2017 alone
After hurricanes, thunderstorms are the most significant severe weather risk for the insurance industry in the United States. A tornado or a violent hailstorm occurring in the centre of a major city can result in extremely high losses.
The situation in the areas to the east of the Rocky Mountains is unique in the world; these areas experience violent and frequent heavy storms, very often accompanied by multiple tornadoes.
Even when adjusted for the increase in value, aggregated losses point to an upward trend in recent decades. In 2017 alone, overall losses from severe convective storms in North America totalled more than US$ 25bn. Around three quarters of that total was covered by the insurance sector. In addition to property damage, a considerable amount was paid out for damage to vehicles.
Severe thunderstorms and climate change
Science has shown that the frequency of meteorological conditions causing the formation of extreme thunderstorms has increased, while substantial loss events have also been on the rise. Climate-model-based studies have identified increasing levels of moisture due to rising ocean temperatures and evaporation rates as the most important driver.
These are substantial indications that climate change is a contributing factor to the increase in (value-adjusted) losses from severe thunderstorms.
Normalised losses from heavy thunderstorms in North America are increasing
Just as in North America, normalised losses from thunderstorms have also increased in Europe
The intensity of thunderstorms in certain regions of Europe has also increased in recent years.
Severe thunderstorms can occur virtually anywhere. However, it is possible to identify areas that have a particularly high probability of thunderstorms and, as a result, a high probability of loss. In these regions, the loss potential can often run into the billions.
In Europe, as in North America, it has been demonstrated that severe thunderstorm hazards — in this case large hailstones and strong gusts — have increased in frequency in some regions, thereby contributing to rising loss potential. This is in addition to increased losses as a result of higher asset values and repair costs.
As increasing moisture levels have been demonstrated to be the main driver, the fact that higher ocean temperatures and evaporation rates lead to a more humid atmosphere indicates that climate change is a contributing factor.
Buildings and infrastructure are particularly prone to losses from violent hailstorms. Loss prevention measures are essential given the pattern of growing losses.