Issue 21.3: June/July 2018
Department

Heads Above Water

The University of Hawai‘i’s Sea Level Center monitors the rise and fall of Earth’s oceans—but mostly the rise
Story by Curt Sanburn. Photos by Elyse Butler.

On Saturday morning, January 13, a high-surf warning goes into effect for the Hawaiian Islands. A storm in the Gulf of Alaska is kicking up forty- to fifty-foot ocean swells that will hit the archipelago broadside, from the north. The warning stands until Sunday night. “Monster surf,” is all an O‘ahu newspaper headline needs to say.

So, early on that sunny Sunday, I head north from Honolulu. Just over the crest of O‘ahu’s central plateau, the view opens up to a panorama of the vast, slate-blue Pacific and the island’s North Shore, still several miles downslope. The entire coast, and its lineup of fabled surf spots—Hale‘iwa, Waimea, Pipeline, Sunset—is cloaked in sea-spray haze. Whitewater paves the nearshore shallows and reefs, while farther out lines of giant waves push landward, cresting and peeling left and right, adding to the froth.

At Pūpūkea, I meet up with photographer Rafael Bergstrom, 36, a tall bodysurfer with a 35-mm camera, a friendly manner and a master’s degree in natural resource management from the University of Hawai‘i. As a volunteer “citizen scientist,” Bergstrom plans to spend this Sunday morning surveying a two-mile stretch of coast and taking pictures of the giant surf’s impacts on the beach itself, on adjacent infrastructure and on the area’s string of paradisiacal if shack-like waterfront properties, most of them perched directly atop the beaches’ back-shore dunes.

Between summer’s “king tides” and winter’s huge surf, Hawai‘i saw several extraordinary oceanic events last year. Island scientists are at the forefront of measuring and predicting these phenomena. Photo: Rafael Bergstrom.

Bergstrom, who’s also a paid staffer with the O‘ahu chapter of the Surfrider Foundation, checks his iPhone: High tide will hit in two hours, so it’s coming up now. The latest surf forecast has dropped to between twenty-five and forty feet, “but still, it’s monster waves,” he says.

We walk along the coast toward Sunset Beach, threading our way through the growing crowds of Sunday surf spectators. The first dramatic scene is at Rockpiles beach, where the district’s busy coastal thoroughfare, Kamehameha Highway, bridges a sandy, low-lying gap in the beach dune. Yellow caution tape cordons off a lifeguard tower and a wet, debris-covered patch of shore. “No swimming,” reads a sign. Here the highway is directly exposed to the surf, and we watch spellbound as a spent wave kicks foaming run-up all across the steep, narrow beach. The rushing water overruns the crest and pours into the gap. With fearsome acceleration, it careens like a wild river smack into the busy highway’s concrete viaduct.

A road crew blocks one of the two traffic lanes, while a speedy front loader shovels sand off the pavement and into a dump truck. Bergstrom crouches and photographs it all.

Bergstrom calls himself a citizen scientist by virtue of his work with the Hawai‘i and Pacific Islands King Tides Project, part of a growing international network of volunteers who monitor the erosional and flooding effects of sea level rise (“SLR” in scientific parlance). The project is open to anyone willing to contribute digital photos plus metadata that show what’s happening on their coasts. Powered by a smartphone app and sponsored by the federally funded University of Hawai‘i Sea Grant College Program, the project has about three hundred active contributors in the Islands and signals a newfound public engagement as Hawai‘i stares climate change and SLR in the face.

“The effects have been getting crazier and crazier every year,” Bergstrom worries as we sit for a minute watching the waves at Rockpiles. “The damages that we’re seeing have to be cataloged, especially now that awareness of climate change is beginning to tick up. We need that visual documentation so that, over time, we can show where the coastline is, was and where it’s going, right before our eyes.”

Bergstrom and I trudge across the wet, heavy sand toward ‘Ehukai and Sunset, wary of run-up. Bergstrom points out how a few of the beachfront properties are shored up behind big, stone-and-mortar walls installed on the sand. Yards are studded with coconut trees, naupaka, false kamani, heliotrope, ironwood trees—salt-loving vegetation that holds the sand, until it doesn’t. Some root-balls are fully exposed but still grip at the gouged dunes while their trees totter.

A one-story house with a large seaside lānai looms above the beach on braced posts. Winter seas have scooped out nearly all of the sand from beneath the house. Daylight gleams through the house’s underside from the eroded gaps in its landward footing. Nearby, a man hammers at framing for a vinyl mesh blanket that drapes a dune’s vertical face, upon which a two-story house sits, about two feet back from the edge. Over the roaring surf, a woman at the house calls down to Bergstrom, asking him why he’s taking so many pictures. She sounds distressed when he tells her, and begins to rail against a government that won’t permit her family to place boulders on the (public) beach in an attempt to save the place. “There’s nothing wrong with people protecting their property!” she shouts.

At Sunset Beach, Kamehameha Highway again kisses the sand for a few hundred yards. The twenty-year-old asphalt bike path on the roadway’s makai, or seaward, shoulder has been undercut and partly collapsed by the sea. This is new to Bergstrom, who guesses the damage occurred during the last big-surf event in December.

In terms of climate change and SLR, last year, 2017, was a wake-up call for Hawai‘i, especially on heavily developed O‘ahu with its million souls. All year long the Islands experienced episodic extreme high tides ranging up to a foot above official predictions. The excessive sea levels were promptly branded with the catchy if non-scientific term “king tides” and became one of the biggest local news stories of the year. Television news footage of submerged roadways, collapsing beachfront homes and a pondlike warehouse district became routine. On Sunday, August 20, a tide gauge in Honolulu Harbor registered the highest sea level ever recorded there.

University of Hawai‘i Sea Level Center director Phil Thompson says an occurrence known as nu‘a kai, or stacked sea, was responsible for last summer’s extreme high tides, seen here in Waikīkī. Photo: Rafael Bergstrom.

The term “sea level” is a built-in contradiction. It suggests a smooth, even layer of water wrapping the planet. But the sea’s “level” is anything but. Higher and lower patches of water splotch the latest computer simulations of the globe’s sea level, shifting with time—and passing storms, melting ice caps, earthquakes, prevailing winds and currents.

The University of Hawai‘i Sea Level Center (UHSLC) is dedicated to measuring, modeling and predicting these fluctuations in sea level. It manages and monitors eighty-four tide gauges positioned through-out the world’s oceans, which are part of a network of 568 such gauges that staff researchers access to collect, analyze and model data, and then make local predictions based on it.

Recently, UHSLC sequentially mapped “blobs” of high water moving across the Pacific during the past two years. Right now it’s working on seasonal forecasting for SLR, according to Director Phil Thompson, 36. “It’s real tricky and really hard,” he says of the center’s latest challenge, “but it turns out that here in Hawai‘i we’ve got some skills developing so we can look up-stream and see what’s headed our way.”

Thompson’s explanation for last summer’s extraordinary flooding events is a fascinating lesson in the inherent complexity of tracking global sea levels. He says they were the result of several oceanic effects that occurred more or less simultaneously, a process that he and others refer to as nu‘a kai, or stacked sea.

The center draws data from a global network of tidal gauges, which the center’s staff uses to make local predictions. Thompson checks a gauge on the Makai Research Pier in Waimānalo, O‘ahu.

First off, he says, there’s the altogether predictable annual highest astronomic tides, which occur when the sun, earth and moon align just so. Last year they were scheduled for late May, late June and late July, roughly when the Islands were hit with news-making ocean flooding. Add to that a warmer Pacific due to a seasonal El Niño event and global sea level rise caused by melting glaciers and warming oceans (water expands as it warms).

On top of all that, there are, in the Hawaiian Islands, big ocean eddies. “The tradewinds do some amazing things,” says Thompson, who got his PhD in physical oceanography and serves as an assistant professor at UH Mānoa. He describes how Hawai‘i’s trademark breezes, blowing a steady fifteen to twenty-five mph, stream over, around and between Hawai‘i’s massive volcanic islands. The Venturi effect causes the wind to funnel, compress and accelerate through the interisland sea channels, which leads to wind-speed differences on the leeward sides of the islands that swirl the ocean into eddies as large as the islands themselves. “We get these spinouts, these eddies that propagate all along the island chain. When they spin, they bulge upward at the centers.”

Of course, the UHSLC predicted the astronomical king tides, but the extreme sea levels were not forecast, Thompson admits. “We didn’t have the scientific knowledge to jump on all these other things that were going on at the same time. We simply weren’t scientifically prepared.” The high-water events last year probably won’t recur this year or next, he says, but warns that they’ll happen more and more frequently due to SLR.

Nu‘a kai comes about from a complicated combination of unseasonably warm ocean temperatures, global sea level rise, wind funnels and other factors. Photo: Rafael Bergstrom.

“People in Hawai‘i are coastal people,” he answers simply when I ask him what’s important to understand. “I see this, the whole project, as a critical conversation between the community and scientists, so that we can see how many lives are affected and how many people are involved in working on the problem. The cooperation going on between different agencies is phenomenal, so that instead of looking at a doomsday scenario, I like to think of it like we’re building a model for how to approach the problem.”

The scientist and new father seems to thrive in the impressive if dizzying world of acronyms: In addition to SLR and his UHSLC, there’s the IOC (UNESCO’s Intergovernmental Oceanographic Commission) and the IPCC (the UN’s Intergovernmental Panel on Climate Change). Thompson serves on a NASA (National Aeronautics and Space Administration) sea level change team; he has a project funded by USGS (United States Geological Survey) and a “small piece” of a project run by NOAA (National Oceanographic and Atmospheric Administration). Furthermore, UHSLC is an integral part of UNESCO’s GLOSS (Global Sea Level Observing System), which distributes its international sea-level data “products” under the umbrella of the GOOS (Global Ocean Observing System).

To dramatically close out last year’s flooding events, on December 30 the state Climate Commission and the Department of Land and Natural Resources’ Office of Conservation and Coastal Lands (DLNR-OCCL) issued the “Hawai‘i Sea Level Rise Vulnerability and Adaptation Report,” which evaluates the effects in the Islands of a 3.2-foot rise in sea level, which according to the latest science appears more and more likely within this century. The 300-page report estimates that 6,500 structures, 38 miles of road and 550 cultural sites will be chronically flooded; 20,000 people displaced; and property losses totaling at least $19 billion.

The report recommends statewide “vulnerability zones” consistent with the report’s island-by-island mapping of Sea Level Rise Exposure Areas (SLR-XA), totaling about 26,000 acres. Planning for infrastructure and other developments in these areas, the authors assert, should be carried out accordingly. The report also suggests limiting permits for shoreline armoring or hardening; that is, the seawalls and rock revetments that have been shown to exacerbate beach erosion and loss.

To make sure the report’s message got out, the state produced an unusually blunt, half-hour documentary that aired repeatedly in early January on prime time local TV stations. In a front-page news story that ran the day the report came out, the Honolulu Star-Advertiser plainly noted, “While the report serves as a framework for identifying and managing climate change threats facing the state, it paints a pretty dire picture for the Hawaiian Isles’ future.”

“Looking at the data, yeah, it’s definitely unnerving,” says coastal scientist Brad Romine when I read him that quote. “But that’s out of necessity, because Hawai‘i’s so vulnerable. Of course, we’re not alone in this—it’s a global problem—but I think the state, out here in the middle of the Pacific, is definitely taking an aggressive, cutting-edge approach to modeling and understanding what sea level rise will mean for our coasts.”

Romine earned his PhD studying beach processes and historic changes to Hawai‘i’s coasts, and contributed to the state’s report. As a Sea Grant extension agent coordinating its Center for Coastal and Climate Science and Resilience, and working with the DLNR-OCCL, he is a liaison among the data-driven conclusions of scientists (including Thompson), policy makers and the local community.

“Other states have done modeling,” Romine points out. “The USGS is doing some sophisticated work in California, and NOAA has modeled still-water sea-level-rise flooding nationwide. But Hawai‘i has such a complex shoreline dynamic—so much wave action, so many precious beaches, a complex coastal geology with so many preexisting erosion problems—that the UH Coastal Geology Group, which had a big hand in the report, pushed the modeling further than ever. Maybe it will be an exemplar for other coastal states and other Pacific Islands to follow.”

Thompson confers with Brad Romine and Maya Walton, both of the University of Hawai‘i Sea Grant Program.

Back on the North Shore, Bergstrom tells me that he attended a “managed retreat” work-shop sponsored by the state’s Office of Planning a few days before. It’s an arresting term, meaning so exactly what it says: to retreat from coastal, flood-prone areas in a way that is planned and executed so as to minimize as much as possible impacts on landowners and everyone else who loves the shore. The goal, according to the symposium’s organizers, was to begin exploring the feasibility of a managed-retreat framework for the state.

About one hundred invited attendees listened to guests from New Jersey and Ventura County, California, outline two separate cases of managed retreat, one involving the state of New Jersey and its purchase of properties (from willing sellers) flooded by Hurricane Sandy, properties that now act as publicly owned buffer zones for future floods. The other had Ventura County deciding to move a parking lot and bike path at popular Surfer’s Point farther inland, rather than hard-armoring the shore.

Bergstrom reports that the workshop brought together scientists, property owners, planners, insurance companies, realtors, the city, the state and the feds to begin to understand and explore what our options might be for moving away from the coastline as sea level rise events eventually become the norm.

“It’s not gonna be an easy conversation in the years to come,” he says, “but I believe there’s nothing else we can do but move away from the water and free up beaches so they can migrate with rising sea levels. We’ve got to liberate our beaches to save them.” HH