Unraveling the unknowns of global tropical cyclone risk in the future

Tropical cyclones (TCs) are among the most devastating natural hazards putting populations and assets at risk. This risk is expected to increase further in a warming climate and with socio-economic development. It is, therefore, of great importance and the aim of our study to assess the drivers and uncertainties of global TC risk in the future. We use a large set of synthetic TCs downscaled from various general circulation models (GCMs) and different warming scenarios of the CMIP6 generation to simulate TC activity at the middle and end of this century. In parallel, we derive economic growth factors from different Shared Socioeconomic Pathways (SSPs) to approximate socio-economic development. We combine these future representations of hazard and exposure data with vulnerability functions to estimate the TC risk increase in the future, using an open-source probabilistic impact model (CLIMADA). Furthermore, we perform a systematic uncertainty and sensitivity analysis to understand which of the model input factors contribute most to the uncertainty in the future TC risk increase. First, we find a non-linear effect between climate change and socio-economic development that drives the total future risk. Second, we show that the choice of GCM affects the output uncertainty most among all varied input factors. However, we note that exposure and vulnerability data are notoriously sparse and that advances in future TC risk assessment also depend on a better representation of these components. Ultimately, unraveling these unknowns of global TC risk in the future may help focus future research efforts and enables better-informed adaptation decisions and mitigation strategies.