Professor Gregor Leckebusch, from the University of Birmingham, comments: “We’re keen to better understand what causes these storm systems to be pulled in a sequence into certain parts of Europe, whether it’s northern France, Benelux, Germany or Scandinavia. We have some indications – there seem to be, on average, two peak periods of clustering activity in certain parts of Europe, but we still have lots to uncover.”
Clustering can have significant impacts for the insurance industry, including costly claims such as those incurred during the 1990 and 1999 seasons, which led to aggregate insurance losses exceeding EUR 20 billion in each year - the costliest on record from European windstorms.
Reinsurance is cover that an insurance company purchases from another insurance company to insulate itself from the risk of a major claims event. Researchers found storm clustering tends to increase later in the windstorm season, with more frequent occurrences observed between January and February - coinciding with the typical renewal period for reinsurance contracts in Europe, which traditionally occurs on 1 January.
The research partnership aims to improve understanding of how specific behaviours of storm clustering can impact reinsurers. While storm clustering is generally factored into established European windstorm models used by reinsurers, anticipating its impact remains a significant challenge. Experts also aim to understand further how the interplay of different meteorological factors determine how storms cluster within a European windstorm season and across the region.
Different regions within Europe experience varying windstorm behaviours at different times of the season. The changing nature of storm clusters presents several challenges for insurers:
- Clustered storms occurring in quick succession can lead to a flood of claims within a short period, making it difficult for insurers to attribute losses to specific events.
- One storm can weaken structures, making them more susceptible to damage from subsequent storms. This cumulative effect can result in significant loss amplification.
- Short intervals between storms in a cluster make it challenging to determine which storm caused specific damages, complicating resolution of claims.
Tim Fewtrell, Head of EMEA Catastrophe Analytics at Gallagher Re, comments: “How successive storms interact is very complex from an insurance claims point of view and when storms cluster in such short succession, separating the cause of loss in claims can be exceedingly difficult.
“We can see that ‘drier’ storms with high wind speeds, for example, may cause damage to roof tiles and other structural elements, whereas a subsequent ‘wetter’ storm could add additional water ingress claims.”
