Can IPCC models be used in cat modelling?

The Intergovernmental Panel on Climate Change (IPCC) predicts that while tropical cyclones (TCs) may becomeless frequent in the future, they are likely to be more severe, with 1.5°C–4°C of global warming causing a 10%–20% increase in the proportion of very intense TCs (those falling into Saffir–Simpson categories 4–5). While IPCC projections are expected to be relevant at global and continental scales, there is thought to be a disconnect between projection and reality when applied at a smaller scale. This is important for insurers and reinsurers that operate at national and regional levels, or that have major peak exposures falling below the IPCC projections’ intended geographic resolution.

To show whether there is a disconnect between IPCC global projections and their regional relevance, we analysed North Atlantic hurricanes – a major source of risk for the insurance market. The IPCC has already projected an increase in the proportion of Category 4–5 TCs at a global scale. Similarly, a 2013 paper, ‘Recent intense hurricane response to global climate change’, detected a 25%–30% increase in the proportion of Category 4–5 TCs in the North Atlantic per 1°C of observed global warming between 1975 and 2010.

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