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Hawaii’s state climatologist says the islands are likely to experience a growing number of hurricanes and other tropical cyclones as the world heats up from climate change in the coming decades.
Ironically, according to Pao-Shin Chu, most global models suggest there will be fewer hurricanes in a warmer world, albeit packing stronger and more dangerous winds and rain.
But in our corner of the Pacific, he said, research points to the likelihood of more hurricanes as tropical cyclones that previously passed to the south shift pole-ward in search of warmer waters at higher latitudes.
The information is found in a new college textbook Chu wrote with Hiroyuki Murakami of the Geophysical Fluid Dynamics Laboratory of the National Oceanic and Atmospheric Administration.
“Climate Variability and Tropical Cyclone Activity” was published by Cambridge University Press.
“As Earth warms, we anticipate extreme events becoming more frequent or more intense, meaning increasing hurricane rainfall, flooding and destructive winds, heat waves, drought and wildfires,” Chu said.
A veteran professor of meteorology at the University of Hawaii at Manoa, Chu said the northern Central Pacific is not considered a hurricane-prone region, but it likely will grow increasingly vulnerable as climate change takes hold and more storms churn into our waters.
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Chu noted that recent hurricanes Lane in 2018 and Douglas in 2020 came close to making landfall on Oahu.
“We’re going to really have to pay attention,” the professor said. “All it takes is one catastrophic event to make a difference. If a major hurricane makes landfall on Oahu, we could have a huge problem.”
In the textbook, Chu and Murakami examine the global climate modes and long-term circulation patterns that affect the various ocean basins found across the Pacific and the Atlantic oceans and tie them all together.
Chu said he spent the past three years reading the latest scientific papers on the topic, many of them discussing how climate change will affect tropical cyclone activity.
Globally, while some models do suggest there will be an increasing number of hurricanes, a majority of the studies indicate there will be fewer storms but they will be more powerful and intense with stronger winds and more rainfall, as tropical circulation becomes weaker to create conditions that are less likely to support hurricane formation.
Tropical cyclones will increasingly amass their power from warmer oceans, and, with more evaporated moisture in the air from the hotter seas, the storms will generate increasing amounts of precipitation, he said.
For Hawaii, years with the El Nino weather pattern generally will result in more hurricanes in the Central Pacific, he said, while fewer hurricanes will be seen in years with La Nina conditions, El Nino’s opposite.
El Nino and La Nina are associated with abnormal water temperatures in the equatorial Central and Eastern Pacific and can affect weather patterns across the globe.
Earlier this month the Central Pacific Hurricane Center predicted that Hawaii would experience a below-average hurricane season for the third year in a row. Each of the past two summers featured La Nina conditions, and more of the same is expected this summer.
But Hawaii can’t always count on a La Nina summer. A study published in 2020 said the number of cyclones threatening the islands could double as the climate warms up.
The study’s modeling suggested the “vertical wind shear” that normally tears apart tropical cyclones approaching the islands is likely to weaken with warm ocean temperatures near Hawaii fueling tropical cyclone genesis.
What’s more, the impacts of land-falling tropical cyclones is likely to be much more severe due to higher rainfall and increasing sea level, with flood risk and storm surge intensified in coastal areas, according to the research.
“Hawaii will be more vulnerable to hurricane risk,” Chu said.
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