Climate costs of tropical cyclone losses also depend on rain

It is well established that climate change will lead to changes in tropical cyclone (TC) characteristics and affiliated impacts to human communities. While a growing social science literature estimates losses from TCs, almost all have characterized TCs by wind speed alone. However, TC winds are commonly accompanied by intense rainfall, both of which will likely be impacted by climate change. We assess the impact of rain on current and future TC losses and estimate the bias in loss calculations from omitting rainfall. Using a TC Integrated Assessment Model utilizing 60 000 simulated TCs making landfall in South Korea, we find rain to be a significant loss determinant. For both the wind-only and wind + rain cases, socioeconomic change will cause a decrease in fatalities and a large increase in property losses due to a shrinking population and growing wealth. Regarding climate change, the wind-only case considerably underestimates the climate costs of TC losses compared to the wind + rain case, driven by notable increases in future rainfall in contrast with minor wind intensity changes. While the relative impacts of TC wind versus rain under climate change will no doubt be different across countries, our results highlight the importance of accounting for both wind and rainfall in research and policy, especially in mitigation and adaptation planning.