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Hawaii Is Sinking Back into the Ocean; Now What?

Originally posted on SURFER | By Dashel Pierson | Last updated Mar 21, 2025 3:08 PM ET

The history of Hawaii, from a geological standpoint, is one of augmentation. Over a million years ago, thanks to some well-placed tectonic plates, and volcanic activity, the islands today known as Hawaii rose from the depths of the ocean, eventually becoming home to early Polynesian settlers, and later becoming America’s 50th state. Oh yeah, and a couple decades down the line, surfing’s mecca, too.

But now, according to a new study from the University of Hawaii, the islands are sinking back into the ocean. And in some places, it’s happening a lot quicker than previously estimated.

“Our findings highlight that subsidence is a major, yet often overlooked, factor in assessments of future flood exposure,” said Kyle Murray, lead author of the study and researcher with the Climate Resilience Collaborative (CRC) at the UH Mānoa School of Ocean and Earth Science and Technology (SOEST). “In rapidly subsiding areas, sea level rise impacts will be felt much sooner than previously estimated, which means that we must prepare for flooding on a shorter timeline.”

According to the research behind the study, they found that the average rate sinking on Oahu is fairly low at 0.6 millimeters per year – about the thickness of your standard sheet of printer paper. However, in certain areas, the subsidence levels are much higher…40 times higher. They found that some regions of Oahu are exceeding 40 millimeters per year, shocking the scientists.

“This rate of land subsidence is faster than the long-term rate of sea level rise in Hawai‘i (1.54 millimeters per year since 1905), which means those areas will experience chronic flooding sooner than anticipated,” said Phil Thompson, study co-author and director of the UH Sea Level Center in SOEST. “In places like the Mapunapuna industrial region, subsidence could increase flood exposure area by over 50% by 2050, while compressing flood preparedness timelines by up to 50 years.”

So, what to do? Well, for now, the data can help urban planners, and residents, prepare for the future.

“Our research provides critical data that can inform state and county decision-making, helping to improve flood exposure assessments, infrastructure resilience, and long-term urban planning,” said Chip Fletcher, co-author, director of CRC, and interim dean of SOEST. “This work directly serves the people of Hawai‘i by ensuring that local adaptation strategies are based on the best available science, ultimately helping to protect homes, businesses, and cultural areas.”

A million years from now, will future humans (if we still exist) speak about Hawaii like the lost city of Atlantis? Let’s hope not.

This article first appeared on SURFER and was syndicated with permission.

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