As sea levels rise, so does erosion. Hawaii offers lessons.

Beyond the Kikiaola Harbor on the western side of Kauai, the beach that surrounds this lush Hawaiian island becomes ragged and, in some places, nearly disappears.  

It does the same on Wailua Beach toward the east, with enough erosion that condominium owners have petitioned to bring in sandbags to protect their property from the approaching ocean. The state highway department is scrambling to protect the Kuhio Highway, the main artery around the northeastern side of this 600-square-mile island.

A bit farther north, Aliomanu Road shows how easily the ocean can smash exposed asphalt. 

Policymakers, residents, and advocacy groups have debated what to do about that roadway, which has at times partially crumbled into the sea. 

Still, this “garden isle”’ of Hawaii – the oldest, and arguably lushest, of the state’s island chain – does not have the dramatic scenes of erosion that have come from nearby Oahu, where at least one home has literally toppled into the ocean. Much of the coastline erosion here is happening incrementally, in this place and that, while many beaches still appear picture-perfect. Even as scientists predict increasing sea-level rise and erosion, many community members still question the immediate impact of climate change.

All of this makes Kauai emblematic of many coastal regions across the United States, from California to North Carolina. Yet Kauai’s success at bringing community groups together also makes the county an important model for those communities trying to figure out how to balance the needs of homeowners, infrastructure, beach preservation, and ecology in a world increasingly shaped by climate change.

“Kauai, in my opinion, is the county that the other counties should be looking to for guidance,” says Chris Conger, vice president of Sea Engineering Inc., a coastal and marine consulting company that works throughout the Pacific. “They are just so thoughtful and so practical, and so caring about their people and community and resources.”

Indeed, over the past decade, the island’s planning department, businesses, homeowners, and community groups have worked together – sometimes through yearslong policymaking exercises – to establish some of the most climate-aware building ordinances in the country.

This doesn’t mean that everyone on the island agrees with policy decisions. Advocates on all sides still argue for more dramatic action in different directions.  

But Kauai is one of the first municipalities in the country to connect building setback laws to scientists’ climate-based sea-level rise predictions. With the rest of Hawaii, it has become the first region in the country to legally mandate sea-level rise disclosures during real estate transfers. Kauai’s government has also revisited shoreline rules and zoning priorities, and together with civil society has started to reimagine the way that the island – with its growing year-round population – will develop over the 21st century.  

And because of all of that, even critics of the government will acknowledge that Kauai officials are working toward a sort of balance that will be necessary across the country to adapt to what the island’s director of planning, Ka’aina Hull, calls “the slow creep of climate change.”

Shifting coastlines

One key challenge for Kauai – as for other coastal areas – is that even without climate change, coastlines shift. 

Native Hawaiians knew this and moved their living structures with the land. But with Western development came a Western belief in permanence, scholars point out. Over the past century, residents and visitors settled near the oceans; built homes, roads, and factories; and basically expected that the landscape would remain static.

But it doesn’t. Especially not with climate change.

According to estimates by scholars at the University of Hawai‘i, warming oceans and rising sea levels will increase the rate of erosion on Kauai by more than 50% by 2050. It could mean the loss of most, if not all, of the island’s beaches by 2100.

“We see climate change in many forms here, and it is intensifying,” says Charles Fletcher, interim dean of the School of Ocean and Earth Science and Technology at the University of Hawai‘i at Mānoa and the former chair of the Honolulu Climate Change Commission. “One of the ways we see impact is in retreating shorelines. If you are a beach and the ocean is rising, you need to migrate; the shoreline needs to move landward. But right there are roads and homes and communities.”

For years, to protect their land, property owners would install some sort of sea wall, made out of concrete or sandbags or other materials, which kept waves from eroding the land. But the problem with sea walls is that they stop beaches from moving landward, essentially drowning them under the rising water, and they divert wave energy farther down the coast, coastal experts say, making erosion even worse on the next swath of land.  

“A beach that is trying to migrate landward running up against a sea wall will erode away and drown, essentially,” Dr. Fletcher says. “And we have lost beaches, miles and miles of coastline that used to have beautiful white beaches on them. Now we just have sea walls with the water lapping right up against the wall.”

This is a particular issue in Hawaii, Dr. Fletcher and others say, because beaches are owned by everyone and form an essential part of local culture. The Hawaii Constitution enshrines the public’s right of access to all beaches and shorelines in the state, below the “upper reaches of the wash of the waves.” There are no private beaches even for the fanciest of oceanfront homes.  

“That’s extremely important to Hawaii, just the identity of who we are,” says Mr. Hull, the planning director. “It’s why we have coastal advocates. ... It’s where our communities go; it’s where they go on the weekend, where they fish, where they die. There are cultural practices still adhered to in many of these areas.”

A sea wall might protect the property behind it, he says. “But that beach is gone forever.”

Mitigation strategies

In 2020, the state of Hawaii outlawed most sea wall construction, realizing that this climate mitigation effort caused a domino effect of other problems. But that decision left some homeowners – and communities – in a perilous situation.

If individuals didn’t try to protect their properties from the sea, they could lose their homes. The ocean could also inundate property cesspools, a situation that could bring about another sort of environmental damage. 

Much of the state’s road network is by the coast, as are military bases, and government officials have long argued that there needs to be some protection of this infrastructure, if temporarily.  

But Kauai already has experience with “temporary” sea walls, many of which were built by homeowners years, if not decades, ago. The litigation necessary to force their removal, government officials say, is significant. 

This convinces some environmental advocates, such as Gordon LaBedz, chair of the Kauai chapter of the Surfrider Foundation, a nonprofit environmental organization focused on protecting oceans and beaches, that the inevitable response to climate-sped erosion is to shift people away from the coast and to have the government move roads inland. Any other decision, he points out, means the end of Kauai’s beaches.

“Beaches are the lifeblood of Hawaii,” he says. “If we lose our beaches, we lose the lifeblood of our economy.”

“A very long journey together”

But moving inland through “managed retreat,” as it has become known, is not the only solution, says Mr. Conger, the coastal consulting executive. On Waikiki Beach in Honolulu, for instance, hotel companies do regular beach restoration, replacing sand to combat erosion. He also suggests that some shoreline stabilization techniques, such as groins that extend perpendicular from the shore and help control sand movement, could provide shorter-term fixes.

“We’re all walking a very long journey together,” he says. “It’s not going to be one step. We’re promoting smaller steps with more time to adapt and manage and change, and others are saying, ‘Let’s just take the giant steps now.’ I don’t think we have to take the step to 2100 today; let’s take a smaller step and plan.” 

For Kauai planner Mr. Hull, this has meant “yes, and.” While the Kauai government still works to protect some roadways, he and his department have also started to look for property on Kauai that could be offered as an exchange for people who might want to give up their ocean plots, he says. Recently, the county government purchased 400 acres on the western side of the island, with the idea of using a section of it to allow for these sorts of land swaps. Mr. Hull says he is also exploring agricultural zoning ordinances on the island and would like to start conversations about whether it might be possible to loosen some of the restrictions on farmland development.  

But, he says, if there is any lesson from Kauai, it’s that none of these steps can happen without a huge amount of community engagement and conversation. After all, coastal erosion is not the only climate change impact here. Kauai has already seen the effects of super-charged storms and intense rainfall, both connected to climate change. In 2018, for instance, the northern part of the island saw some 50 inches of rain in 24 hours – an unprecedented deluge that caused both landslides and flooding. 

Sea-level rise has also caused inland flooding on many of the Hawaiian Islands when storm surges pushed seawater back through drainage pipes. Making changes anywhere requires balancing all sorts of interests, from tourists and hoteliers to community activists and homeowners. 

“Kauai has taught us a lot,” says Stefanie Sekich, senior manager of the Coast & Climate Initiative of the Surfrider Foundation. “The biggest lesson, especially in an island state, is to stop building in harm’s way. The second biggest lesson learned: Work with the community.”