Unlike previous years, this summer’s king tides — the highest of the year — captured our attention.
It could be because they were more than 9 inches higher than predicted in April and May, breaking a 112-year-old record.
It could be because the tides created some dramatic scenes: Fish swimming in flooded Mapunapuna, water flowing over city streets, concrete barriers shoved around.
It’s also likely that thanks to years of dire warnings, we have a new frame of reference for coastal flooding — it’s not just a seasonal nuisance anymore, but a harbinger of things to come. Climate change is on our minds, as it should be.
It is becoming harder and harder to ignore the evidence of persistent rising seas in a warming world, especially in the Pacific. Coastal erosion and sea-level rise already have shrunk or inundated low-lying islands in the Solomon Islands and elsewhere, forcing inhabitants to relocate or flee.
Fortunately, we’re not there yet; Hawaii’s fate hasn’t been sealed, and there’s still time to prepare. But how, and for what?
The answers should come into clearer focus by the end of the year, when the state releases a new study, the statewide Sea Level Rise Vulnerability Assessment and Adaptation Report. In advance of the report’s release, a series of public informational meetings were held across the islands, including two meetings this month in Hilo and Kailua-Kona, with the final one scheduled for Sept. 12 on Molokai.
The renewed efforts to prepare Hawaii for the long-term effects of climate change stem from Act 83, the Hawaii Climate Adaptation Initiative Act. The act, passed in 2014, created an interagency committee to prepare the technical report, which is expected to provide some guidance on how the state should plan for this vulnerability.
Sam Lemmo, administrator of the state Department of Land and Natural Resources’ Office of Conservation and Coastal Lands, said the report will model a 3.2-foot sea level rise, which these days sounds relatively modest.
“It’s not going to stop there, unless something miraculous happens,” he said. The latest science, he noted, suggests that “it is physically plausible that sea level could rise by as much as 6 feet.”
What effect rising seas will have on Hawaii will depend on location and geography. Hawaii island, for example, may better withstand coastal erosion and flooding than certain parts of Oahu, with its heavily urbanized shorelines.
A recent study by the University of Hawaii’s School of Ocean and Earth Science and Technology (SOEST), modeled the potential effects of a 3-foot sea level rise on Waikiki. The flooding caused by rising groundwater and other factors could threaten $5 billion of taxable real estate and flood nearly 30 miles of roadway, the study concluded. It could also inundate many cesspool sites, potentially releasing effluent and causing a public health hazard.
When could all this happen? In 10, 20, 50 years?
“No one really knows,” Lemmo said. There are too many variables. Even so, it should be self-evident that plans should be made to address this sort of thing, sooner rather than later.
Lemmo said the report will contain numerous recommendations for policymakers. Among them:
>> Incorporating sea-level-rise considerations at all levels of state and county land-use planning and zoning, based on the best available science and the vulnerabilities of each location.
>> Protecting our beaches, which are vital for our tourist economy. “They will be the first thing to go with sea level rise,” Lemmo said. To protect them could require a ban on development and allowing beaches to recess inland.
>> Possibly putting essential capital improvement projects, such as roads, sewers and airports, out of harm’s way. At some point, relocation might make more financial sense than continuous repairs.
The bottom line: For the long term, it seems that serious adaptive engineering, combined with a managed retreat from current shorelines, will be necessary. It will be difficult and expensive. Best to start now.
