Tropical cyclone climatology change greatly exacerbates US extreme rainfall\u2013surge hazard

Avantika Gori,Ning Lin,Dazhi Xi,Kerry Emanuel

doi:10.1038/s41558-021-01272-7

Avantika Gori, Ning Lin + Show 2 more

Open Access

https://doi.org/10.1038/s41558-021-01272-7

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Abstract

Tropical cyclones (TCs) are drivers of extreme rainfall and surge, but the current and future TC rainfall–surge joint hazard has not been well quantified. Using a physics-based approach to simulate TC rainfall and storm tides, we show drastic increases in the joint hazard from historical to projected future (SSP5–8.5) conditions. The frequency of joint extreme events (exceeding both hazards’ historical 100-year levels) may increase by 7–36-fold in the southern US and 30–195-fold in the Northeast by 2100. This increase in joint hazard is induced by sea-level rise and TC climatology change; the relative contribution of TC climatology change is higher than that of sea-level rise for 96% of the coast, largely due to rainfall increases. Increasing storm intensity and decreasing translation speed are the main TC change factors that cause higher rainfall and storm tides and up to 25% increase in their dependence.

Highlights

Tropical cyclones (TCs) are drivers of extreme rainfall and surge, but the current and future TC rainfall–surge joint hazard has not been well quantified
It is unclear how future changes in TC climatology and sea-level rise (SLR) will alter the severity and spatial variation of extreme rainfall–surge hazard across the US Atlantic and Gulf coasts, what will be the relative contribution of storm climatology change and SLR to changes in the joint hazard and how changes in TC characteristics are related to changes in rainfall hazard, storm surge hazard and their dependence
We quantify the relative importance of the change of different climatological variables in driving the changes in joint extreme event return period (JRP) (Methods) and find that TC climatology changes drive larger increases in the joint hazard compared with SLR

Summary

Discussion

The results presented here demonstrate that TC climatology change and SLR may cause large increases in joint rainfall–surge hazard across the US East and Gulf coasts. The future JRP change calculated by holding TC frequency constant at the historical level is only slightly lower at each coastal location (up to 149-fold decrease in JRP; Supplementary Fig. 7), and the spatial trends (that is, higher JRP change in the north compared with the south) are unchanged. We find that the statistical dependence between extreme rainfall and storm tide increases in the future for portions of the coastline, resulting in a higher probability of multi-hazard extremes during future storm events This finding is important because many previous studies of future compound flooding have neglected potential increases in hazard dependence[8,9,10,41], which could underestimate compound flood risk. Received: 11 August 2021; Accepted: 20 December 2021; Published online: 3 February 2022

Methods

Findings

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