Economic assessment of tropical cyclone (TC) hazards over Vanuatu

Abstract The historical TC-related cost-intensity relationship is examined using documented costs of TCs that passed within 50 km of Vanuatu over the period 1972–2023. These are used to estimate the cost of TCs (i.e., for ~ 72% of TCs that passed within 50 km of Vanuatu) that have missing cost records. These estimates, combined with the reported records, create a database of historical TC costs for Vanuatu which was absent until now. It is shown that the mean cost per TC, over the historical period is VT 6.39 billion (USD 56.02 million) or 5.3% of GDP (scaled to the 2023 GDP value). The cost, however, is quite sensitive to TC intensity: it is directly related to almost the seventh power of the maximum windspeed (in kilometres per hour: km hr − 1 ). Estimates of the mean cost per TC and annual average cost under a warming climate are also presented. Estimates using the above power law show that by late-century (2090), the mean expected cost per TC could increase to 5.2–5.6% of GDP (an increase of VT 0.97–1.59 billion) under a low emissions scenario or 8.3–11.5% of GDP (an increase by VT 5.45–10.06 billion) under a high emissions scenario. Projections using models further show that TC frequency could decrease in future. Combining the above changes in cost per TC with the projected decrease in TC frequency in future, the annual average cost by late-century (under a high emissions scenario) could increase to VT 13–18.6 billion yr − 1 in comparison to the historical annual total cost of VT 8.34 billion yr − 1 .