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Dec 14, 2023

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The question isn’t if the sea level is rising but how quickly

Bradley Romine talks about expected sea level rise over the next century during a public meeting Thursday night at the county Planning Department building. -- The Maui News / COLLEEN UECHI photo

Many scientific bodies agree that sea levels are rising, but the question has long been how quickly it will happen.

That’s up to the people, experts say.

On Maui and Hawaii island, where the sea is rising at a slightly faster rate than around other islands, the issue may come up sooner than later. And while a look at the latest maps shows Maui’s beaches aren’t on track to disappear tomorrow, or even within the next 10 years, the state wants to start preparing now.

“There’s one thing we know in terms of climate change,” said Samuel Lemmo, administrator of the Office of Conservation and Coastal Lands. “We know that sea level is rising, we know that it’s going to continue to rise and we know that it’s going to accelerate in the future.”

As Hawaii puts together its first statewide exam on the impacts of rising sea levels, residents on each island are having to ask: What’s actually at risk, and what needs to be done?

Samuel Lemmo answers questions from the public during a public meeting on sea level rise Thursday. -- The Maui News / COLLEEN UECHI photo

Coastal concerns

Climate change has long been a hot-button issue as scientists and politicians on both sides of the aisle debate its reality and severity.

But, in Hawaii, visible shoreline erosion has been hard for beachgoers and lawmakers to ignore. In 2014, growing concern prompted action at the state Legislature in the Hawaii Climate Adaptation Initiative that declared climate change “the paramount challenge of this century.” It called for a special committee under the state Department of Land and Natural Resources to put together a report on the impacts climate change could have on Hawaii’s economy, environment and way of life. The newly formed Interagency Climate Adaptation Committee chose to focus on rising sea levels, a specific topic with direct impact on the Hawaiian Islands.

Two years in the making, the state’s Sea Level Rise Vulnerability and Adaptation Report is due to the Legislature in December. While much work has been done, the data are still very preliminary and subject to change, committee co-Chairman Lemmo emphasized during a public meeting Thursday.

Both the bill and the report are timely, he added. Global temperatures in 2014 made it the hottest year since modern record keeping started in 1880, NASA and the National Oceanic and Atmospheric Administration concluded in separate studies. Then 2015 set the bar even higher, followed by 2016.

“So we’re writing this report at a time when global temperatures are breaking records left and right,” Lemmo said. “I don’t mean to scare anybody, but all this stuff is sort of interesting.”

When global temperatures go up, the ocean absorbs a lot of the heat, said Bradley Romine, a coastal geologist and coastal management specialist with the University of Hawaii’s Sea Grant College Program and the DLNR. As water gets warmer, it expands. This, combined with increasing runoff from glaciers and large ice sheets, contributes to sea level rise.

Globally, sea level rise has been accelerating over the past century and is expected to continue doing so, Romine said, referencing data from the United Nations’ Intergovernmental Panel on Climate Change. By the year 2030, the global mean sea level rise is predicted to be around 0.6 foot, then 1 foot by 2050, 2 feet by 2075 and 3.2 feet by 2100. That’s the “business as usual” scenario, or what would happen if no changes were made, Romine said.

“The question with that is the timing,” Romine said. “When do we see that 3 feet of sea level rise? A lot of that depends on how well we begin to reduce our greenhouse gas emissions as well as understanding the science a little better about how these major ice sheets are responding.”

Maui’s outlook

While 3.2 feet may sound like small potatoes to some, it could mean greater erosion of Maui’s beaches and greater flood risks for homes and hotels in low-lying areas. Statewide, 70 percent of beaches are eroding. On Maui, it’s 80 percent.

“Of course (with erosion) there’s a number of factors, natural and human,” Lemmo said. “The one caused by people is most notably just poor coastal development decisions over the past century — building way too close to shoreline and then building seawalls to protect structures. . . . The other issue is because of climate change and sea level rise.”

Maui’s rising sea level rate is just above that of Oahu and Kauai, which each experience around 1.4 millimeters, or 0.06 inches, of sea level rise a year, according to the state’s climate adaptation website. Maui sees about 2 millimeters, or 0.08 inches annually, while Hawaii island sees 3 millimeters, or 0.12 inches a year.

This is likely because Hawaii island is very large and still growing, while sinking under its own weight, Romine said.

“Maui, because of its close proximity to the Big Island, is probably being dragged down to a certain degree,” he said.

While that’s a factor in Maui possibly losing some of its coastline, “it’s happening on geologic time frames” that are beyond human control. On the other hand, the concern with sea level rise “is that it’s happening on human time frames,” Romine said.

As part of its study, the committee took a look at what 3.2 feet of higher sea level could mean for each island. Pointing to maps of Kihei and Kaanapali, Tetra Tech oceanographer Kitty Courtney showed blue patches, representing water, encroaching on beaches and properties along the South and West Maui shorelines. (Tetra Tech is a global consulting, engineering, program and construction management firm.)

Researchers added up the property and structure values of the impacted areas and found that with 3.2 feet of sea level rise, the estimated costs to Maui island would total around $3.2 billion, impacting 640 residential and 50 commercial structures, Courtney said. However, the data are preliminary and don’t include damages to roads and utilities.

Courtney acknowledged that the “economic part of this is not going to be a complete picture.”

“We can only do what we have right now, which is property values,” Courtney said. “But I think what we do have is a really strong picture of is the actual exposure.”

She added that the researchers are required to revisit their results every five years, and that other scientific groups regularly publish new information.

“This just needs to serve as our baseline,” Courtney said. “We’re trying to get something down now that we can start with.”

Turning data into plans

Lemmo emphasized that the state’s report is not a plan or policy. It’s simply a study that the department hopes can be used to plan for Hawaii’s future.

But residents are concerned that the report didn’t paint a complete picture of the economic impacts of sea level rise. They pointed out that the loss of a hotel goes beyond property value, undercutting both jobs and tourism. They also wanted more analysis on the economic losses from eroded beaches and cultural sites.

Maui Planning Commission Member Wayne Hedani hopes to see a follow-up study on the impacts to airports, roads, sewage treatment plants and other infrastructure.

But, “it’s a good start and it could be very helpful planning tool for the state,” Hedani said after Thursday’s meeting.

Some predictions may be decades away, but Hedani considers them “right around the corner.”

“Because the planning process takes so long, and making adjustments to critical infrastructure takes such a long time, I think it’s important to integrate what they’re saying with our future plans — community plans, the Maui Island Plan,” Hedani said.

Kai Nishiki, a community organizer for Malama Olowalu, also hopes to see a more comprehensive study in the future.

“To me it’s shocking to think about the coastal inundation that will happen to us,” Nishiki said. “I do think it’s expected, and that a lot of people have been aware of this issue, and that it’s just taken a long time for people to really come to terms with what that actually means.”

Nishiki said that Maui needs to focus on coastal retreat, prioritize the realignment of Honoapiilani Highway and put “a moratorium on all coastal development until we have a plan in place with these inundation maps.”

Maui County targets three main areas in response to sea level rise: coastal sand dunes, erosion updates and post-disaster reconstruction, according to the state’s climate website.

For the county, this has meant restoring and protecting sand dunes, which help prevent erosion, filter pollution from runoff and provide natural habitats. It’s also meant updating county erosion rate maps that help planners decide where to draw setbacks along the coast. And, it’s meant holding community meetings to discuss how the county can improve its reconstruction methods following a natural disaster. The goal, planners said, is to cut down on “harmful short-term solutions.”

Lemmo just hopes the state report will spark more action.

“The major fear I have . . . is that we’re going to go through this whole process and we’re not going to do anything about it,” he said.

* Colleen Uechi can be reached at cuechi@mauinews.com.

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