News•May 8, 2013

Hawaii at Growing Risk of Hurricanes, Studies Show

Despite living in the middle of the tropical Pacific Ocean, Hawaiians haven’t had to worry much about hurricanes, thanks to prevailing ocean currents and weather patterns that typically deflect or weaken storms before they make landfall. But according to a new study, that may soon change in ways that could have far-reaching consequences for Hawaii’s military, transportation and energy infrastructure, as well as its tourism industry, the lifeblood of the islands. All would be extraordinarily vulnerable to sea level rise and storm surge-related flooding.

Damage to a structure in Kauai caused by Hurricane Iniki in 1992.
Credit: Wikimedia Commons via FEMA.

The new study, published in the journal Nature Climate Change, found that environmental conditions will become more favorable for tropical cyclones in and around the Hawaiian islands by 2075-2099. That’s due, in part, to a northwestward shift in the tropical cyclone track as well as increased ocean temperatures in the central tropical Pacific, which will help alter weather patterns.

Currently, tropical storms and hurricanes tend to curve out to sea well south and east of Hawaii after spinning up off the west coast of Mexico or in the Central Pacific. Hawaii has been affected by only eight named storms since 1979. The last big one was 1992’s Hurricane Iniki, which dealt a severe blow to the island of Kauai, but missed the more heavily populated and strategically important island of Oahu.

The possibility that future storms may threaten Hawaii has given pause not just to scientists, but policy makers as well.

Hypothetical scenarios of a hurricane reaching landfall near Honolulu have been presented to military officials and civilian policy makers in recent years, most recently at a 2012 workshop at the University of Hawaii. Those scenarios show potentially devastating consequences for Hawaii’s main port, military hub, energy facility, and tourism industry. Most of these facilities are located barely above sea level, making them vulnerable to storm surge as well as long-term sea level rise.

“Under direct-impact scenarios, there is the potential for much of Honolulu and most of Waikiki to be inundated,” said a 2012 study on potential storm-surge impacts on Hawaii, which was published in the journal Ocean Modeling. The study projected flooding up to several kilometers inland in the famous tourist destination of Waikiki Beach, much of which was built from drained marshlands.

Hawaii’s main oil refinery, located at Barbers Point, is situated in one of the lowest-lying areas on Oahu. “If you lose that, you essentially lose most of your energy,” said Chad Briggs, strategy director for Global Interconnections LLC, who helped lead the 2012 workshop while consulting for the U.S. Air Force, and has conducted scenario-planning exercises and research for the Department of Energy.

Briggs said a more diverse energy portfolio, which includes renewable energy sources, could improve Hawaii’s ability to withstand major storms without widespread energy disruptions.

The reef runway at Honolulu International Airport, on the island of Oahu.
Credit: Wikimedia Commons.

Another key at-risk facility is Honolulu International Airport, the island’s primary connection to the mainland and Asia. The airport features a 2-mile long runway built on an offshore reef, which a 2012 study predicted would be underwater if a strong hurricane made a direct hit on Honolulu.

Briggs said the main container port on Sand Island in Honolulu is also extremely vulnerable to flooding, which would disrupt food imports. “If you have a big storm surge you are going to lose that port,” Briggs said.

That could quickly cause food shortages, since Hawaii only has about a 3- to 5-day food stockpile, he said, relying as other areas do on “just-in-time delivery.”

The military, which could withstand a severe storm by sending its aircraft and ships away from the islands ahead of time, might be forced to aid island residents with food and gas deliveries as well as search and rescue operations while temporarily based on other islands due to damage at its normal bases, something they may not have trained for.

Briggs said a hurricane striking Honolulu head on isn’t really the worst-case scenario, either. Many more vulnerabilities can be brought to light by combining threats in unexpected ways, which more accurately represent real-world events. For example, he said scenario planning showed that Hawaii is especially susceptible to damage from a 1-2 punch of a tropical storm or hurricane followed in rapid succession by another storm, or by another very real threat to Hawaiians — a tsunami generated by a Pacific Rim earthquake.

While the new study, which was conducted by researchers based in Japan, Hawaii, and China using high-resolution computer models, projects a significant increase in the frequency of storms that may threaten Hawaii, the overall number of storms will still be lower than many other hurricane-prone regions of the U.S. For example, Florida was hit by four hurricanes during the 2004 hurricane season alone.