A new study that examined rising sea levels and shoreline changes found that the current rates of erosion of Hawaii’s beaches will double by midcentury and steadily worsen by the end of the century, threatening thousands of homes, many miles of roadway and other assets.
Meanwhile, a bill in the state Legislature was approved by a joint Senate panel Monday that would set aside part of the transient accommodations tax to help fund beach replenishment.
Senate President Donna Mercado Kim said she’s hoping $3 million to $5 million can be set aside each year for what would be a new beach restoration and conservation special fund.
"It is one of the most important things that we need to focus in on, because we are known for our beautiful beaches, our sand, our environment," Kim said, "and if that should go, that would be so detrimental to the economy and to the environment."
A research team with the University of Hawaii and the state Department of Land and Natural Resources conducted the new coastal erosion study, published this week in the journal Natural Hazards.
Ten beaches on Kauai, Oahu and Maui were examined for the study. If these beaches were to follow historical trends, an average 20 to 40 feet of shoreline loss would be expected by 2050 and 2100, respectively.
But the researchers found that sea level rise boosted the erosion rate by an average 16 to 20 feet by 2050 and an average of nearly 60 feet by 2100.
"This means that the average amount of shoreline recession roughly doubles by 2050 with increased sea level rise, compared to historical extrapolation alone. By 2100 it is nearly 2.5 times the historical extrapolation," said Tiffany Anderson, lead author and postdoctoral researcher at the UH-Manoa School of Ocean and Earth Science and Technology.
Current research suggests that the global sea level will rise about 3 feet by the time the 21st century comes to a close.
Many beaches are already eroding, but the study found that more than 90 percent of Hawaii’s shorelines will be retreating by 2050.
More than 13 miles of the state’s beaches has been lost to erosion in the past century, and chronic erosion is already happening at 70 percent of beaches on Oahu, Kauai and Maui, according to a study by the U.S. Geological Survey.
"The erosion rate is going to be horrendous," said Sam Lemmo, administrator of the state Office of Conservation and Coastal Lands. "We have to adjust or adapt to those rapid changes that are going to be occurring because of rapid sea level rise. We need to have a total package, not just like throw sand on the beach."
The construction of sea walls and buildings that are too close to the shore may be contributing to the problem, officials said. If the bill passes, the department could devote more resources to addressing erosion through planning, establishing shoreline setbacks and ordinances that would guide future development, Lemmo said.
The Tax Foundation of Hawaii opposed the bill, arguing that earmarks decrease government accountability and should be avoided.
But Kim (D, Kalihi Valley-Moanalua-Halawa) argued that having dedicated funds under House Bill 444 would allow the state to move quickly and avoid having to come back for legislative approval and waiting until it costs more to fix problems.
"It’s too much at stake," Lemmo said. "It’s half of our economy."
A 2008 economic impact analysis of the potential complete erosion of Waikiki Beach suggested the economic impact on hotel revenues alone could be as much as $661.2 million annually, with hotel industry job losses of 6,352 and lost visitor expenditures reaching nearly $2 billion.
Coastal scientists have said it appears there will be a time in the following decades when Waikiki Beach will have to undergo constant sand replenishment in order for it to even exist.
As part of the new study, researchers developed a model to help government officials assess future erosion hazards under higher sea levels caused by the climate crisis, said Chip Fletcher, associate dean at the School of Ocean and Earth Science and Technology and co-author of the paper.
To further improve the estimates of climate impacts, the researchers said their the next step will be to combine the new model with assessments of increased flooding by waves.
Matthew Barbee and Neil Frazer with UH and Bradley Romine with DLNR also contributed to the paper. The research was sponsored by DLNR and the U.S. Geological Survey Pacific Islands Climate Science Center.
More than 220 people are expected to attend a conference at the Hawai‘i Convention Center this week that will focus on sea level rise and other natural disasters.
"The Rising Pacific: Currents of Change and Solutions for Resilience" will be held Tuesday, Wednesday and Thursday, and will feature speeches, panel sessions and professional development training courses.
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The Associated Press contributed to this report.
