The Maui News
DEC 30, 2017
The projected 3.2 feet of sea-level rise by 2100 could submerge or destroy 300 structures, 11 miles of coastal highway, 3,130 acres; cause $3.2 billion in economic losses on Maui; and threaten the tourism industry, a new report commissioned for the state Legislature said.
The 304-page "Sea Level Rise Vulnerability & Adaptation Report," presented to the Hawaii Climate Change Mitigation & Adaptional Commission, was developed under the leadership of the state Department of Land and Natural Resources Office of Conservation and Coastal Lands. It was mandated by the Legislature and is the first statewide assessment of Hawaii's vulnerability to sea-level rise, a news release Friday said.
The report was completed ahead of a Sunday deadline.
"Rapid warming of the atmosphere and oceans, caused by two centuries of unabated carbon emissions, is causing increasing rates of sea-level rise, unprecedented in human history, threatening natural environments and development on low-lying coasts," the executive summary of the report said.
State Office of Planning Director Leo Asuncion said that the report is intended to serve as a framework for identifying and managing climate change threats facing Hawaii.
The report utilizes the current best available science on climate change and sea-level rise and is considered a "living" report to be updated as more data become available. Much of the modeling for the report is based on a 3.2 feet of sea-level rise by 2100 as projected by the Intergovernmental Panel on Climate Change.
The 23-page section of the report focusing on Maui offers some alarming projections based on models.
"With 3.2 feet of sea-level rise, low-lying coastal areas around the island . . . would become chronically flooded within the mid- to latter-half of the this century," the report says. "This land will become submerged as a result of coastal erosion, coastal flooding from tides and waves or become new wetlands behind the shoreline from rising water tables and reduced drainage."
Waihee, Hana, Lahaina and Kihei are the major communities vulnerable to the effects of sea-level rise, the report says. The Waihe'e Coastal Dune and Wetlands Refuge would be permanently flooded, new wetlands would form in Hana and on Front Street and parts of Kihei would face chronic flooding with the 3.2 feet of sea-level rise.
Low-lying areas like Spreckelsville would face increased frequency and severity of flooding and make them impassable or uninhabitable, the report said.
The potential economic losses islandwide would range from $1.7 billion for 1.1 feet of sea-level rise to $3.2 billion for 3.2 feet of sea-level rise. There would be about 760 structures lost with 3.2 feet of sea-level rise, including hotels in West Maui, the report said.
"With 3.2 feet of sea-level rise, potential economic loss would occur in low-lying coastal areas islandwide, with the greatest loss in West Maui due to the concentration of high-value residential and commercial land and structures," the report said.
The beaches that visitors come to Maui to enjoy are threatened as well. With 3.2 feet of sea level rise, 16 miles of unprotected beachfront development will be exposed to erosion and flooding, the report said. The report is critical of seawalls and other beach armoring, saying that the structures will destroy more beach area.
Instead, "managed retreat" and beach nourishment "could help extend the life of beaches such as Kaanapali," the report said.
"Maui's famous beaches will increasingly be eroded and permanently lost if hard structures such as roads and seawalls impede their landward migration," the report said. "The flooding of hotels and transportation systems, along with the loss of beaches, would impact the tourism economy and thus impact the people whose livelihoods depend on it."
Some recommendations offered include recognizing the report's sea-level rise model in general and community plans, adopting "balanced retreat strategies," encouraging development outside the model's flood zones, implementing flood resiliency standards, requiring mandatory disclosure of vulnerable properties and embracing the model to expand special management areas along the coast.
"I think seeing it in black and white is surprising, but I think we have all observed what has been going on countywide, especially in West Maui and the north shore," Deputy Planning Director Michele Chouteau McLean said Friday. "To see the magnitude is striking."
She thinks the report will be "a catalyst for the counties and the state to devote more resources to addressing this problem."
Maui County was the first in state to adopt a shoreline setback formula that factors in erosion and paid for a study to see if there was beach quality sand off Kahana Bay, which there was, McLean said. The study provided an opportunity for beach nourishment.
She noted that the Lanai Planning Commission, which has jurisdiction over the SMA process, is in the final stages of amending its SMA boundaries.
"Certainly, these reports will be factors in determining SMA boundaries," she said.
The county also has been acquiring shoreline properties when they become available to keep them from development in a proactive measure and working with individual property owners where erosion is threatening structures to find "the most responsible way" to deal with their problems, she said.
As far as the plan's proposal to sacrifice some areas in a managed inland retreat, McLean pointed out that Mayor Alan Arakawa has said there will come a time when buildings will be lost to the sea. She added that some properties allow for relocating buildings while others are narrow shoreline parcels that do not allow that.
State Sen. J. Kalani English, whose district includes Hana, said that the report "provides critical data as we work to reinforce the state's resiliency and address the impact of climate change."
"How we strategize and develop legislation to strengthen our state begins with understanding the risks and recommendations," he said. "This is important information to consider as we continue to be a leader in climate change mitigation."
The report is available at climateadaptation.hawaii.gov/wp-content/uploads/2017/12/SLR-Report_Dec2017.pdf.
* Lee Imada can be reached at firstname.lastname@example.org.