Catastrophic event of moderate to high frequency, distinct from major primary perils (major hurricane, major earthquake), whose accumulation produces increasingly significant annual losses.
Secondary perils designate a class of natural events of higher frequency and lower unit severity than the major primary perils, but whose recurrence and aggravation under climate change generate growing and increasingly unpredictable annual losses. They include primarily severe convective storms (hail, tornadoes, straight-line winds), pluvial and fluvial floods, wildfires, landslides, droughts and heatwaves. The term is relative: a hurricane is the primary peril, but the coastal flooding and landslides it induces are its secondary perils. Between 2012 and 2022, Swiss Re estimates that secondary perils accounted for 70% of global insured losses from natural catastrophes. This share reflects both better insurance penetration in areas with high wildfire or convective storm potential (North America, central Europe) and the climatic worsening of these events. Secondary perils pose a specific challenge to classical catastrophe models, designed for primary perils: their frequency is harder to model, their spatial distribution is less concentrated, and their non-stationary trend invalidates historical series. They are now at the center of reinsurance portfolio reviews.
The 2023 convective storm season in central Europe (Germany, Austria, northern Italy) produced nearly 8 billion euros in insured damage, exceeding the losses of several years of primary perils. No single event exceeded 1 billion euros, but the accumulation of dozens of hail events between April and September saturated annual aggregate excess-of-loss reinsurance programs.
secondary peril, risque secondaire, aléa secondaire, convective storm, wildfire, inondation pluviale