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One Hurricane Is Rare In Hawaii, And The State Might See Two This Week

Hawaii faces a rare threat this week, and a possible preview of climate change: Two hurricanes — Madeline and Lester – are expected to pass very close to the islands in quick succession. Data from the National Oceanic and Atmospheric Administration’s Office for Coastal Management shows that this likely hasn’t happened since at least 1949, when reliable weather record keeping began in the Central Pacific.

The threat coincides with President Obama’s Wednesday visit to Hawaii, where he will address a meeting of Pacific heads of state on environmental conservation. Neither hurricane is expected to affect the meeting on Oahu, but a potential meteorological disaster so close by will add an exclamation point to Obama’s message, which is expected to emphasize the urgent need to address climate change. Later on the trip, Obama is scheduled to visit remote Midway Atoll, near where he recently expanded what is now the largest marine protected area in the world, and attend the G20 summit in China, where he is reportedly going to enter the United States formally into the 2015 Paris accord on climate change.

Meanwhile, Hawaii’s Big Island — the most likely target of the storms — is preparing for Madeline and Lester. A hurricane warning is now in effect for the island, where public schools will close to serve as storm shelters should conditions warrant, and Hawaii Gov. David Ige signed an emergency proclamation on Tuesday, speeding up the flow of state aid, if needed.

If you haven’t heard much about Hawaii as a hurricane hot spot, you’re not alone. Ocean waters surrounding the islands, while warm, are generally not warm enough to support frequent hurricanes. For the storms that do form, a nearby semipermanent high-pressure center usually acts as an atmospheric deflector shield. However, ocean temperatures have been exceptionally high near Hawaii lately, leading to increased activity. That’s likely tied to the El Niño phenomenon, but some evidence suggests that climate change could also be resulting in more frequent hurricanes in the Central Pacific.

Although Tropical Storm Iselle made landfall on the Big Island in 2014 and Tropical Storm Darby did so just last month, no hurricane has hit there since 1949. Hurricane Madeline could be the first, forecast to pass “dangerously close” on Wednesday night, and Lester could be the second, expected to pass through the region on Saturday. Both are expected to be Category 1 storms on their closest approach to Hawaii. The Central Pacific Hurricane Center warns that Madeline alone could bring 5 to 15 inches of rainfall to windward-facing slopes of the Big Island.

If either Madeline or Lester makes landfall on the Big Island, the storm likely won’t survive to greatly affect other islands. As was already the case with Tropical Storm Darby this year and Iselle in 2014, the Big Island’s twin volcanic giants, Mauna Kea and Mauna Loa, would disrupt and shred the circulation.

Since 1949, just five storms of tropical storm strength or greater have made landfall on any island in Hawaii, including two in the past three years. Having two hurricanes hit in the span of just a few days would be exceedingly rare. (Iselle, in 2014, was at hurricane strength until just before landfall and was followed several days later by Hurricane Julio, which veered northward away from the islands.) In fact, only two hurricanes have made landfall anywhere in Hawaii since records began being kept, and they were 33 years apart. The most recent was Iniki in 1992, a Category 4 hurricane that made landfall on Kauai, causing about $3 billion in damages (adjusted for inflation) and interrupting the final days of filming of “Jurassic Park.”

In recent years, Hawaii’s hurricane threat appears to have grown, although whether that is a symptom of natural climate variability or human-caused climate change is a subject of scientific debate. Philip Klotzbach of the Tropical Meteorology Project at Colorado State University said that although Hawaii’s official hurricane records go back to 1949, the record is most reliable after about 1970, when satellites began to provide complete coverage of the most remote parts of the Pacific. Before that, it’s possible that the record missed a similar one-two punch like what may occur this week. Still, Klotzbach said that even with a relatively short record, “these two in potentially rapid succession is a bit surprising.” Klotzbach wrote in The Washington Post last year that 2015 was the most active Central Pacific hurricane season on record by far, boosted in part by record high ocean temperatures.1

Researchers such as Klotzbach have long known that El Niño — a natural phenomenon featuring warmer-than-usual water in the eastern tropical Pacific Ocean — tends to produce especially active hurricane seasons between Hawaii and Mexico. El Niño happens only every two to five years, but it’s connected to about 60 percent of Hawaii’s 17 hits or close brushes with tropical storms and hurricanes since 1949 (through Tropical Storm Darby). So it’s not surprising that after a very strong El Niño in 2015-16, there’s been an uptick in tropical cyclone activity near Hawaii.

But there’s growing evidence of a possible climate change signal, too. In a new review of the causes of the hyperactive 2015 season that has been submitted to the Journal of Climate, a research team led by Hiroyuki Murakami of Princeton University found that abnormally high ocean temperatures consistent with human-caused climate change played a “dominant role” in boosting the frequency of Pacific hurricanes, in addition to the natural effect from El Niño. Although the rarity of Hawaiian hurricanes makes any background climate change signal difficult to detect, the study concludes that “extreme years, like 2015, are likely to become more common in the near future.” A study published in 2013 led by Murakami predicted a two- to threefold increase in hurricanes near Hawaii, compared to averages in 1979 through 2003, by the late 21st century.

In an email, Murakami said that although his most recent results were based on the 2015 hurricane season, “they are also applicable to the 2016 summer season.” If climate change is already playing a role in boosting Hawaii’s hurricane threat, Obama’s climate message this week couldn’t have better timing.

Footnotes

  1. The Central Pacific is a subsection of the Northeast Pacific mentioned in Klotzbach’s tweet here.

Eric Holthaus is a meteorologist who writes about weather and climate. His articles have appeared in Slate, Vice, Quartz, the Wall Street Journal, and Rolling Stone.

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