HONOLULU (HawaiiNewsNow) - The same July weekend large surf from Tropical Cyclone Fernanda swept across east shores, Hawaii also saw, for the third time in just a few months, another round of record-level high tides. These "king tides" over the summer sent water washing over seawalls, coming dangerously close to homes and making some roads virtually impassable.
"We found water bubbling up through a manhole cover in Ala Moana parking lot, we see Mapunapuna flooded by water, we found salt water coming out of storm drains and flooding gutters in Waikiki and portions of Kakaako," said Chip Fletcher, associate dean and professor of geology and geophysics at the University of Hawaii's School of Ocean and Earth Science and Technology.
The combination of the two events might be considered an anomaly today, but researchers say extreme weather like this could be the norm: Over the next 50 to 100 years, Hawaii could see tides that could make roads like Ala Moana Boulevard undriveable; oceans so warm that coral, which serves as a habitat for marine life, die off in vast stretches; and an alarming rise in frequency and intensity of destructive tropical cyclones.
All of these events pose a potentially unprecedented threat — one state officials are scrambling to prepare for — to just about every aspect of life in the islands, from critical infrastructure to the state's cultural resources to native flora and fauna to Hawaii's no. 1 industry: tourism.
"We would expect more impactful events, so if our projections are right, this is definitely very bad news for Hawaii," said Kevin Hamilton, UH atmospheric science researcher and former director of the International Pacific Research Center.
To put it another way, this summer's king tides — which swallowed up much of Waikiki Beach for hours at a time — were a glimpse of what Hawaii's future could be just a few decades from now.
"These king tides are an opportunity for us to see what our community looks like under a sea level that is 10 inches higher than present," said Fletcher, a preeminent climate change researcher in Hawaii who's been studying coastal effects for years.
King tides a glimpse of rising sea levels
King tides — an Australian term used to define a very high tide that could lead to flooding in a coastal community — are a result of several factors. Those include the Earth's proximity to the moon, the circulation of water (or what scientists call a mesoscale eddy) and a large swell event.
But 30 to 45 percent of it comes from long-term sea level rise, Fletcher said, which is ultimately caused by "anthropogenic climate change." In other words, an overall warming of the atmosphere and ocean caused by human activities.
The latest report from the Environmental Protection Agency estimates that the average U.S. temperature will rise by about 3 to 12 degrees by 2100 -- if humans continue emitting greenhouse gases into the atmosphere.
"Unless we make a very big change in the global economy, then I think we can bet on definitely warmer and less comfortable summers at sea level in Hawaii," Hamilton said.
And by the end of the century, conservative models put sea level rise on Oahu at 1.7 feet.
The worst case: Nearly 11 feet.
"The scientific community is in agreement that sea level rise has already started to accelerate and it's going to continue to accelerate, so as we move forward in the next few decades, the component of king tides that is due to sea level rise is going to increase in percentage," said Fletcher, adding that humans are warming the atmosphere at unprecedented rates and that more than 90 percent of that excess heat is stored in the ocean.
In Hawaii, special planning committees are already looking at how to prepare and adapt for the potential impacts stemmed by climate change. Sea level rise is something that they're well aware of and accept, but they're looking at how to work around a problem that will threaten critical infrastructure along shorelines on every island.
"We're in a very precarious situation," said Sam Lemmo, co-chair of the state commission charged with exploring climate change adaptation and mitigation. "Our state is completely surrounded by water. We are in the middle of the Pacific basin."
Lemmo, who's also the administrator of the state Office of Conservation and Coastal Lands, added that an extremely "tragic" situation is unfolding in his mind.
"We're really dealing with a very complex, wicked, giant problem," he said. "Even though the ship is sinking — if you want to call it the Titanic — people are going to fight to the bitter end."
Coral threat risks marine food chain
That excessive heating of the ocean also contributed to a mass global coral bleaching event from 2014 through 2017, which the National Oceanic and Atmospheric Administration deemed as the longest coral bleaching event to date, damaging two-thirds of the Great Barrier Reef off the coast of Australia.
The bleaching spread to Hawaii — home to 85 percent of coral under U.S. jurisdiction — and killed approximately half of all coral reefs.
Bleaching occurs when coral expel symbiotic algae — which provides the coral with their color — and when the algae flee, the coral turns translucent. But many fish species thrive on coral reefs, which serve as homes and nursery grounds.
"At some point in their life, 25 percent of all marine organisms pass through or spend time in a coral reef environment," Fletcher said. "When you bleach a reef repeatedly and kill that ecosystem, it has a ripple effect throughout the entire marine food chain."
Fletcher said this was a phenomenon largely caused by warming ocean temperatures, but it was also partly due to El Niño, a natural recurring warming in the equatorial Pacific Ocean that influences air and moisture movement around the globe.
Climate change could lead to more and stronger El Niños, which could not only mean more coral bleaching, but also extreme weather effects like intense rainfall, record-setting heat waves and massive surf, to name a few.
In 2015, a particularly strong El Niño year, Waimea Bay saw one the most prestigious big-wave surf competitions: the Quiksilver in Memory of Eddie Aikau Invitational. It took six years for organizers to give the contest a green light because that's how long it took for waves to reach the required face heights of 40 feet during the narrow three-month holding period.
Warmer water temps mean more cyclones
Perhaps one of the most unforgettable summers that year was the record-breaking number of tropical cyclones that raged through the Pacific and came eerily close to the state -- all thanks to a strong El Niño.
According to Kevin Hamilton, El Niño can lead to enhanced tropical cyclone formation because the storms typically get their energy from heat emitted from the top of the ocean.
A general rule of thumb, he says, is ocean temperatures higher than 80 degrees become more conducive to more storms and stronger storms.
Hawaii has been lucky in a sense that the tropical cyclones that came close to the islands in 2015 didn't actually make landfall, and much of that was because the waters in the Central Pacific tend to be a little cooler than in the East Pacific. That means there's a greater chance they'll fall apart the closer they get to the islands.
"Storms in the Eastern Pacific are forming in much warmer water, closer to the equator," Hamilton said. "Then they move northwest, and the further north they come, the more close to Hawaii they come, they're coming over colder and colder water."
But that could change in time as El Niños develop on top of an overall warming. If the waters warm 4 or 5 degrees by the end of the century, there could be an alarming rise in tropical systems forming in the Central Pacific by the end of the century, specifically a 60 percent increase in storms that could cause potentially catastrophic damage to Hawaii.
'The curve is swinging up'
Past events, no matter how destructive, can offer tools to help us better understand how to prepare for the future, Hamilton said, pointing to Hurricane Iniki in 1992 as an example. Iniki was one of the strongest hurricanes to make landfall in state history, responsible for six deaths and causing approximately $1.8 billion worth of damage.
"If hurricanes are going to become more common, not just once a century, but once every 10 or 20 years, then maybe we should be thinking about changing the infrastructure, whether we should protect our power grid, whether we should have so many houses that are not well grounded," Hamilton said.
There's no single approach on how to deal with and brace for the potentially damaging effects of climate change, but there's one thing researchers can all agree on: The reality is, these weather events are revealing measurable signs of climate change and, rather than looking at them in fear, they should be looked at as an opportunity to prepare now for what could be in store for the state in the next few decades.
"There are things actually happening now as we speak," Lemmo said. "I think the curve is swinging up. But that doesn't mean we don't have time."
This is part of an ongoing Hawaii News Now web series on climate change.