Estimating impacts of North Atlantic tropical cyclones using an index of damage potential

An index of North Atlantic tropical cyclone (TC) damage potential due to winds and coastal surge is developed using seasonal climate variables of relative sea surface temperature and steering flow. These climate variables are proxies for the key damaging TC parameters of intensity, size, and forward speed that constitute an existing cyclone damage potential index. This climate-based approach has the advantage of sidestepping the need for data on individual TCs and explains 48 % of the variance in historical cyclone damage potential. The merit of the cyclone damage potential is in assessments relative to past events or past periods, and may be translated to actual damage using relationships between the damage potential index and specific exposure and vulnerability characteristics. Spread in the change in damage potential over the 21st century among climate simulations under representative concentration pathways 4.5, 6.0, and 8.5 is found to be less than the spread due to internal variability, as assessed using a climate model initial condition large ensemble. This study highlights the importance of accounting for internal climate variability in future climate impact assessments.