Increased U.S. coastal hurricane risk under climate change

Abstract

Several pathways for how climate change may influence the U.S. coastal hurricane risk have been proposed, but the physical mechanisms and possible connections between various pathways remain unclear. Here, future projections of hurricane activity (1980–2100), downscaled from multiple climate models using a synthetic hurricane model, show an enhanced hurricane frequency for the Gulf and lower East coast regions. The increase in coastal hurricane frequency is driven primarily by changes in steering flow, which can be attributed to the development of an upper-level cyclonic circulation over the western Atlantic. The latter is part of the baroclinic stationary Rossby waves forced mainly by increased diabatic heating in the eastern tropical Pacific, a robust signal across the multimodel ensemble. Last, these heating changes also play a key role in decreasing wind shear near the U.S. coast, further aggravating coastal hurricane risk enhanced by the physically connected steering flow changes.

A global increase in nearshore tropical cyclone intensification

“…4c). The meridional dipole-like response of VWS over the Central and North American region is mainly excited by enhanced heating over the tropical Pacific 47 , with a secondary contribution from anomalous diabatic cooling over the tropical North Atlantic (Supplementary Fig. 9a).…”

“…Previously, CMIP5 models did not have consensus regarding an El Niño-like warming pattern in the future 66 . Although the potential for enhanced future warming in the eastern Pacific has emerged more clearly in the CMIP6 multimodel ensemble, considerable inter-model spread remains 47,66 . Further work is needed to reduce uncertainty in model projections of the tropical ocean-atmosphere mean state.…”

“…The SWM 44 utilized in this study is the dry dynamical core of the NOAA/GFDL spectral model, with R30 horizontal resolution and 24 vertical sigma layers. Here, we perform five independent integrations using the SWM, following a previously used experimental design 47 . Our control experiment (CTRL) solves deviations in surface pressure, three-dimensional temperature, and wind from the zonally symmetric climate during the near-future period of 2015-2034.…”

On the Sensitivity of Coastal Hypoxia to Its External Physical Forcings

“…It remains therefore unclear to what extent the high winds and high precipitation associated with a typical cyclone could play significant counteracting roles in modulating overall Bay hypoxia. It is also notable that the ongoing increase in the frequency of cyclones (e.g., Balaguru et al., 2023) will make extreme precipitation events and/or extreme wind events more frequent in the Bay. However, such an increase in storm frequency is unlikely to alter the long‐term increasing trend of hypoxia dictated by warming temperatures (e.g., Frankel et al., 2022).…”

“…It is also notable that the ongoing increase in the frequency of cyclones (e.g., Balaguru et al, 2023) will make extreme precipitation events and/or extreme wind events more frequent in the Bay. However, such an increase in storm frequency is unlikely to alter the long-term increasing trend of hypoxia dictated by warming temperatures (e.g., Frankel et al, 2022).…”