Tropical cyclones: those making landfall at right angles to the coast – which are more dangerous – are likely to become more frequent in the event of high emissions

The angle at which waves strike the coast affects the marine surge. Simulated using 14 climate models, it has changed little to date but will change significantly by 2099 under the highest-emission scenario.

The angle at which a tropical cyclone makes landfall strongly influences the height of the sea surge, but its evolution with warming remained unknown. Cong Gao and Ning Lin analysed the proportion of landings almost perpendicular to the coast, a priori the most penalizing for submersion.

A signal still drowned in variability

Between 1980 and 2024, this proportion increases slightly on a global scale, without the trend being statistically significant or in any ocean basin. The PepC-Global trajectory model, fed by reanalyses, correctly reproduces the angles observed. Forced by the outputs of 14 models from the CMIP6 project, it found the same modest increase over the historical period, which suggests a climate-related component that is not yet detectable.

In a high-emission scenario, on the other hand, the share of perpendicular arrivals increases significantly until 2099, with the most marked changes on the east coast of the North Pacific. No overall trend appears in an intermediate scenario. The authors emphasize that the increase comes from a local change in angles and not from a geographical shift in landings, and argue for integrating this dimension into the coastal risk assessment.