Study: Climate change increases hurricane threat

  • Flow depth for an Iniki-like hurricane that made landfall on Oahu. COURTESY PHOTO

HILO — A new study by researchers at the University of Hawaii at Manoa School of Ocean and Earth Science and Technology indicates that as the climate changes in the coming decades, the northward shift of hurricanes toward the Hawaiian Islands will increase chances of landfall, and storm surge will pose severe flood risks to population and infrastructure along coastlines and further inland.

By studying information from computer models for climate change, hurricane formation and intensity, storm surge, and waves, Ning Li, ocean wave model systems specialist and lead author of the study, and her co-authors estimated future vulnerability to the combined effects of sea-level rise and the closer proximity of hurricanes.

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Li acknowledged the focus of the study is urban Honolulu, but added, “I think the Big Island will be the first to taste it. In the last few years, there have been a few hurricanes that have (approached) the Big Island from the east, so I think we’ve already seen the signal.”

According to the study’s authors, climate change can potentially increase the severity of natural hazards through the end of the century, thereby reducing the reliability or safety of structures.

“With high tide and the projected sea-level rise, the … results from a direct landfall of an Iniki-like hurricane on the south shore of Oahu showed extensive inundation of downtown Honolulu and Waikiki,” Li said. “Other hurricanes passing near Oahu can also produce severe surge and high surf, causing coastal flooding.

“The findings of our study were not a surprise,” added Kwok Fai Cheung, senior author of the study and professor of ocean and resources engineering. “Our recent experience with increasing number of storms tracking closer to the islands — for example, Hurricane Guillermo in 2015, Hurricane Celia, Darby, and Lester in 2016, Hurricane Lane and Olivia in 2018 — has already confirmed the change of hurricane patterns. The damage caused by Hurricanes Lane and Olivia underscores the importance and urgency of coastal storm hazards mitigation. This research should draw attention from state and federal agencies.”

Jonathan Price, professor of geography at the University of Hawaii at Hilo, said the Big Island will face different impacts than Oahu.

“It’s a little bit apples and oranges,” he said, in reaction to the study. “We have significant agricultural interests, so that’s a different kind of potential damage. That was something that we saw with (Hurricane Michael) in the Florida panhandle.”

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Li stopped short of suggesting state or local governments should consider a moratorium on coastal development, but urged developers and urban planners to consult inundation maps developed in the course of the study.

“When you’re building something, there is definitely a risk. It’s about how much risk you are willing to take,” she said. “The inundation maps from this study will help assess the types of buildings and structures in the areas of Honolulu that would be exposed to increased flood risks.”