The University of Hawaiʻi at Mānoa has identified a large-scale tropical disturbance called the Madden–Julian Oscillation (MJO) as a significant driver of the islands’ climate, including extreme events, such as the extraordinary rainfall Hawaiʻi experienced in March and April. This weather pattern travels eastward through the tropics every 30–60 days and, , significantly boosts rainfall during its active phases, particularly on windward slopes.

This research advances scientific knowledge of the processes that influence ±á²¹·É²¹¾±ʻ¾±â€™s climate and can help improve forecasts one to three months in advance.

“Understanding how the MJO affects ±á²¹·É²¹¾±ʻ¾±â€™s climate helps explain rainfall variability on timescales of weeks to months,” said Audrey Nash, lead author of the study and doctoral candidate in the in ¶«¾«Ó°Òµ ²Ñā²Ô´Ç²¹â€™s . “The MJO evolves slowly and can be monitored in real time. Understanding its influence can help scientists and forecasters better anticipate periods of heavy rainfall, drought conditions, and shifts in weather patterns across the islands.”

High-resolution data reveals the pattern

While the MJO was known to influence weather patterns across the tropics, its impact on Hawaiʻi had not previously been examined in detail at timescales of one to three months.

Nash and Giuseppe Torri, associate professor of atmospheric sciences, analyzed long-term, high-resolution atmospheric and rainfall datasets covering Hawaiʻi and the surrounding Pacific Ocean, including data from the Hawaiʻi Climate Data Portal. By compositing rainfall, temperature and atmospheric variables across different phases of the MJO, they identified consistent patterns showing how the MJO modulates rainfall and climate conditions across the Hawaiian Islands.

“We expected a small impact, but it was surprising how consistently rainfall across the islands responds to active and suppressed phases of the MJO,” said Nash.

Active phases of the MJO are also associated with cooler temperatures, higher humidity and stronger northeasterly winds across the islands. The authors note that these patterns appear to be linked to large-scale atmospheric responses to the MJO, including slow moving Rossby waves in the central North Pacific and strengthening of the local Hadley Circulation, a major feature of global atmospheric movement that cools the tropics and warms the poles.

“Improving our understanding of rainfall variability is critical for water management, agriculture, and hazard preparedness,” said Nash. “This work reflects the University of ±á²¹·É²¹¾±ʻ¾±â€™s mission to study the unique environmental systems that shape life in the islands and to provide science that benefits local communities.”

In 2025, Hawaiʻi experienced its second–driest year in more than a century, alongside persistently above average temperatures throughout the year—a stark reality detailed in the inaugural . Published by the , this first-of-its-kind report uses plain language, along with easy-to-interpret maps and figures, to summarize statewide rainfall, temperature, and drought conditions over the past year.

The report is designed to connect communities, resource managers, and policymakers with the climate data behind what many experienced firsthand, providing essential information to support climate preparedness and long-term planning across the islands.

This report reflects decades of effort to monitor Hawaiʻi’s climate and conduct high-level scientific research, paired with more than eight years of collaboration by a team of climate and data scientists to develop an expanding suite of high-quality climate maps and decision support tools. These maps are hosted on the Hawaiʻi Climate Data Portal (HCDP) and, for the first time, make it possible to summarize climate conditions consistently across the entire state.

“Throughout 2025, we heard people across the state talking about just how hot and dry the year felt,” said Ryan Longman, director of the Hawaiʻi Climate Data Portal. “Now we have the data to show what people were experiencing on the ground. We hope this type of reporting helps connect residents to their own lived experiences with Hawaiʻi’s climate and gives communities the information they need to plan for what’s ahead.”

The report is accompanied by a detailed, interactive website that allows users to explore the same climate information for individual islands and even for specific ahupuaÊ»a or watersheds. Together, the report and website provide a clear picture of what many residents across Hawaiʻi experienced firsthand in 2025.

Highlights from the report

• 2025 was the second driest year in Hawaiʻi’s 106-year record, with statewide rainfall averaging just 42 inches—about 20 inches below the 30-year average.
• Maui experienced its driest year on record, while Hawaiʻi Island recorded its second driest year.
• Rainfall was below average for 11 out of 12 months, and August ranked as the driest August in the past 35 years.
• Statewide, 2025 ranked as the sixth warmest year on record, averaging 0.8°F warmer than normal. For Maui and Kauaʻi, it was the third warmest year since 1990.
• Drought conditions were widespread and severe. By the end of the year, 65% of the state was classified as abnormally dry or worse, and all of Molokaʻi experienced dry conditions. The most intense drought occurred in February, when 56% of HawaiÊ»i was in severe drought or worse.

Future data collection to expand

Looking ahead, the establishment of the Hawaiʻi Mesonet is expected to further improve the quality and detail of future reports by expanding on-the-ground climate observations. This report marks the first in a new annual series, to be released at the start of each year and refined and expanded over time as Hawaiʻi’s climate data and monitoring networks continue to grow.

The report also announced the launch of monthly climate update summaries, expected later this spring, which will send the latest information on rainfall, temperature and drought directly to subscribers’ inboxes, with a focus on the parts of the island chain that matter most to the individual subscribers.

“The goal of the monthly climate summaries is to provide an early signal of emerging rainfall and drought conditions,” said Longman. “By delivering site-specific information at the scales people actually work at, these updates can support more proactive planning and decision-making.”

The report was compiled by the Hawaiʻi Climate Data Portal and Hawaiʻi Mesonet teams. Funding was provided by the National Science Foundation, the State of Hawaiʻi Commission on Water Resource Management, and the U.S. Geological Survey Pacific Islands Climate Adaptation Science Center.

A new tool developed by University of Hawaiʻi researchers allows anyone in the state to generate custom, site-specific climate reports to support decisions related to drought, wildfire and land management—a major step forward in Hawaiʻi’s climate resilience efforts.

The was unveiled at a May 2025 meeting of the Hawaiʻi Climate Data Portal (HCDP) User Group, which drew lawmakers, emergency managers and wildfire officials. The new system lets users select or draw an area of interest, enter basic details and receive a tailored climate portfolio by email. It is free to use and portfolios are generated and delivered in less than an hour.

“We used to generate these portfolios one at a time, but the demand for them was so great that we decided to automate the entire process,” said Ryan Longman, lead researcher on the HCDP project and the ¶«¾«Ó°Òµ consortium director of the .

The tool is part of the larger project, which is working to transform how the state tracks weather, drought and wildfire risk using advanced climate modeling, real-time data systems and artificial intelligence. Change Hawaiʻi is part of the Established Program to Stimulate Competitive Research or .

Real-time dashboard

At the meeting, researchers also rolled out a newly developed, open-source dashboard for the Hawaiʻi Mesonet—a growing network of 110 weather monitoring stations statewide, 66 of which are now operational. Each station collects 21 environmental variables and generates more than a million data points daily that feed into predictive models for wildfire and drought.

• Read more about the dashboard on ¶«¾«Ó°Òµ News

“This dashboard puts real-time data at the fingertips of the people who need it most,” said Tom Giambelluca, Hawaiʻi Mesonet project lead, Change Hawaiʻi co-principal investigator and former director of the at ¶«¾«Ó°Òµ. “High-quality data has never been easier to access, and future applications with the data are limitless.”

Wildfire system

The team has developed daily wildfire probability maps and forecasts statewide through the use of optimized machine learning models for more accurate fire behavior forecasting and drought assessment. The user-friendly, real-time data is accessed through the HCDP, which is publicly available. Read more on ¶«¾«Ó°Òµ News.

The goal is to provide early warning to fire managers, emergency responders and landowners so they can deploy resources, issue public advisories and reduce risks through more informed planning. This wildfire system can identify critical wildfire ignition factors, including relative humidity, temperature, rainfall, normalized difference vegetation index (components of wildfire fuel) and land cover.

Future efforts will leverage robust cyberinfrastructure, advanced data visualization, and innovative AI and machine learning applications, including computer vision and edge AI systems, to create a more resilient Hawaiʻi.

A recent round of federal funding cuts included the termination of a $3 million grant from the Office of Naval Research to the University of Hawaiʻi at ²ÑÄå²Ô´Ç²¹. The grant, awarded to Chip Fletcher, interim dean of the (SOEST), supported the (CRC), which provided data and high-resolution modeling of sea level rise impacts, heat exposure and precipitation extremes—critical tools that inform decisions made by state and county agencies, urban planners, infrastructure designers, and emergency managers.

“The loss of federal funding for Hawaiʻi’s climate and sea level rise research will have devastating consequences for the state’s ability to plan, adapt and protect its people and resources,” said Fletcher.

“The models we develop and their supporting databases underpin key pieces of Hawaiʻi’s climate legislation and coastal permitting regulations, including assessments of flood risk, groundwater inundation, coastal erosion, coastal construction setbacks and public safety. Without sustained federal investment, Hawaiʻi will lose its capacity to provide accurate climate projections tailored to island topography, severely hampering our preparedness for compound hazards such as king tides, rain-at-high-tide flooding and storm-driven flooding.”

CRC employed 15 people, including graduate students, climate researchers, policy experts and geospatial analysts. To prepare for and adapt to the growing threats related to climate change in Hawaiʻi and the Pacific region, this team gathered data and developed new modeling tools that reduce vulnerabilities to community and infrastructure on the island of Oʻahu.

Specifically, the CRC team has been modeling the impacts of sea level rise including flooding, coastal erosion, drainage failure, wave impacts at higher sea level and groundwater pollution with higher sea level.

Data guides land management, policies

Various state laws and policies rely on CRC data and models: construction setbacks on Maui, Kauaʻi, and Honolulu; mandatory disclosure of sea level rise impacts in real estate transactions; Special Management Area designations on Maui and Oʻahu; Kauai County sea level rise constraint district; and the required analysis of sea level rise impacts in state Environmental Policy Act, including environmental impact statements and environmental assessment permits.

“The loss of these data systems will undermine the scientific foundation of climate resilience policies, stall progress on community adaptation, and increase the vulnerability of coastal populations, public infrastructure, and cultural heritage,” Fletcher emphasized. “Maintaining federal support is not just about sustaining science—it is about safeguarding Hawaiʻi’s future.”

—By Marcie Grabowski

A new study from the University of Hawaiʻi at ²ÑÄå²Ô´Ç²¹ revealed that a lesser-known Pacific climate pattern can bring heavier spring rains—and a higher risk of flooding—to parts of Hawaiʻi, while also playing a key role in worsening droughts during dry phases. An example of this happened in the spring (March–May) of 2018, in which this climate pattern contributed to an extensively rainy season.

Most people know about El Niño-Southern Oscillation (ENSO), which is known to have a significant impact on climate across the Pacific, including Hawaiʻi, and adjacent continents. However, new research led by ¶«¾«Ó°Òµ ²ÑÄå²Ô´Ç²¹ atmospheric scientists revealed that the Pacific Meridional Mode (PMM), another climate pattern that operates in the eastern Pacific Ocean, plays a major role in the variability of rainfall in Hawaiʻi. Their study was published in the .

They determined that in spring, a “positive” PMM state precipitates extensive rainfall across the state, specifically, greater rainfall throughout the islands occurs as cold fronts move through. Additionally, whether the positive state occurs in winter or spring, the result is that the leeward sides of the Hawaiian Islands experience an increase in extreme rainfall events, suggesting a heightened risk of floods. Their analysis also showed that a “negative” state of the PMM corresponded with reduced daily rainfall over windward sides of the islands, potentially exacerbating drought occurrences.

Population growth, increased demand for water

As the state of Hawaiʻi experiences population growth, the demand increases for water for drinking, food production, agriculture, recreation, construction, medical uses and more.

“This uncertainty in interannual rainfall, together with the increasing demand for water, requires us to better understand the relationship between rainfall and climate variability. We aim for our research to empower our communities with climate and weather information,” said Pao-Shin Chu, study co-author, professor of in the ¶«¾«Ó°Òµ ²ÑÄå²Ô´Ç²¹ (SOEST), and Hawaiʻi State Climatologist.

During the positive state of the PMM, weaker trade winds in the northeast Pacific Ocean between Hawaiʻi and Baja California occur along with increased sea surface temperatures. During the “negative state,” stronger trade winds and cooler surface temperatures prevail.

Chu and lead author Bo-Yi Lu, who was an atmospheric sciences doctoral student in SOEST at the time of this research, performed diagnostic analyses using a combination of actual weather and sea surface observations, and weather model-generated data to determine how these patterns affect rainfall variation.

“Our study suggests that although El Niño emerges as the primary driver of winter rainfall variability in Hawaiʻi, the Pacific Meridional Mode has a pivotal role in spring rainfall, particularly for Maui and the Island of Hawaiʻi,” said Chu.

“Importantly, our analysis disentangles the respective roles of ENSO and the PMM in driving rainfall variability across seasons and types of weather disturbance in Hawaiʻi,” said Lu. “These findings not only deepen our understanding of regional climate dynamics but also offer valuable insights for water resource management and disaster preparedness in Hawaiʻi and beyond.”

—By Marcie Grabowski

A new real-time dashboard launched by the University of Hawaiʻi at ²ÑÄå²Ô´Ç²¹ offers public access to live weather data from nearly 70 monitoring stations across the state, marking a major milestone in the Hawaiʻi Mesonet project. The launch coincides with Wildfire Awareness Month and represents a pivotal moment in the effort to make climate data available to the public.

Hawaiʻi’s diverse geography and microclimates present unique challenges that require precise monitoring to accurately capture weather events. Annual rainfall in parts of Maui, for example, can vary by more than 140 inches within a single mile. The Hawaiʻi Mesonet’s data has the potential to inform planning and decision-making in emergency management, agriculture, water resource, conservation and many other sectors.

Developed by an interdisciplinary team of scientists at ¶«¾«Ó°Òµ ²ÑÄå²Ô´Ç²¹ and the Hawaiʻi Department of Land and Natural Resources, the project aims to deploy 100 high-tech weather stations to provide critical data for forecasting, disaster response and improving climate resilience. The dashboard is expected to play a critical role in supporting wildfire and flood early warning systems, particularly as climate-related disasters are expected to become more frequent and severe.

• Access the dashboard

The dashboard allows users to view current weather conditions at stations spanning the Hawaiian Islands, including temperature, rainfall, wind, humidity, solar radiation and soil moisture. The real-time data is updated every 15 minutes, creating one of the most comprehensive and timely weather data resources available in the state.

“This dashboard represents years of effort to build a system that’s tailored to Hawaiʻi’s unique needs,” said Tom Giambelluca, Hawaiʻi Mesonet project lead, long-time professor in the , and former director of the ¶«¾«Ó°Òµ (WRRC) “It’s not just about data—it’s about giving our communities the tools to adapt and respond.”

The launch comes as federal agencies such as the National Weather Service and NOAA face data removal and staffing cuts under the Trump administration. With gaps in data availability growing, the Hawaiʻi Mesonet system is poised to become a key source of reliable, localized weather intelligence.

Data from the system is stored in Hawaiʻi Climate Data Portal (HCDP), which is available to the public and is used to create recently launched new wildfire risk maps and other climate maps. The HCDP pulls data from multiple sources, including the Hawaiʻi Mesonet and as well as other federal datasets.

“The real concern is that most of these federal datasets will no longer be available in the near future—making the Hawaiʻi Mesonet and the HCDP the sole resource for real time weather and climate information in the state,” Pacific Islands Climate Adaptation Science Center University Consortium Director Ryan Longman said. “A big uncertainty is how the state will fill critical funding gaps left by the federal government to support these important efforts.”

For more information, visit the Hawaiʻi Mesonet website.

A team of five students, including University of Hawaiʻi at ²ÑÄå²Ô´Ç²¹ graduate student Cameron Richardson, won one of three top prizes of $10,000 at an international pitch competition focused on approaches for removing carbon dioxide from the atmosphere.

The student group, which also includes three students from Dalhousie University and one from Acadia University, represented Canada and the U.S. in the during the in Larvik, Norway.

“The competition provided an invaluable professional development opportunity for our entire team, and allowed me to make meaningful international connections in the carbon dioxide removal sector, an industry I am considering working in after my graduate research,” said Richardson.

Equlantic Aquatic Monitoring Inc., the new startup founded by the student group, aims to improve monitoring of carbon dioxide removal in marine environments. The students were chosen from a pool of more than 100 other teams as finalists to make their pitch in Larvik, Norway.

Innovations in monitoring carbon dioxide removal

In an effort to combat rising levels of CO₂, researchers and industry leaders are looking for ways to actively reduce carbon levels in the atmosphere. Among the approaches is marine carbon dioxide removal, wherein carbon from the atmosphere is transformed and sequestered in the deep sea. Along with innovations that prompt carbon sequestration, scientists are developing new ways to assess and monitor the effectiveness of these approaches.

The Equlantic team designed a sensor package that measures ocean-based water quality, specifically the marine carbonate system. Their design, called the Auto-Spec Carbon Analyzer, integrates commercially-available sensors that measure pH, temperature, salinity and carbonate.

“Our device, now patent pending in Canada, can reduce uncertainty in our understanding of the carbonate system in areas undergoing various stages of marine carbon dioxide removal,” said Richardson. “The device also autonomously collects water samples, which can be processed in the laboratory with traditional methods afterward for validation of the autonomous sensor measurements.”

As finalists in the competition, they made a seven-minute presentation to an audience of carbon-management leaders. Equlantic feels optimistic about the market potential for the project. They are now trying to make this concept a reality, having secured additional funding to develop a prototype this coming summer.

See the entire story on the .

Scientists at the University of Hawaiʻi have developed new wildfire risk maps to better predict fire danger across the state. Unlike the current Red Flag Warning system, which relies on weather from a limited number of stations, these maps provide a daily, high-resolution look at the most current fire ignition risks statewide.

“This new mapping system gives us a clearer, more detailed picture of wildfire risks across Hawaiʻi. By providing daily updates and a long-term dataset, we hope to improve preparedness and help protect communities from future fires,” said Professor Sayed Bateni of ¶«¾«Ó°Òµ ²ÑÄå²Ô´Ç²¹â€™s (WRRC) and .

Publicly available on the Hawaiʻi Climate Data Portal (HCDP), the maps are easy to access and available to communities and emergency responders to alert them to the risk of potential wildfires. Users are able to zoom in to a particular area to assess the current fire risk, and generate customized packages of data to export from the portal. Historical fire risk maps are also available for the past 20 years.

The maps are generated using real-time data obtained from various weather networks across the state including the . The Hawaiʻi Mesonet currently consists of over 60 advanced weather stations with a total goal of 100 within the next two years. These stations provide valuable weather and climate monitoring and forecasting. The data collected can also be used for water resource management, agriculture, ranching, ecosystem and cultural resource protection and more.

“It’s all about improving preparedness, especially in light of recent disasters like the devastating wildfires in Los Angeles and the tragic Lahaina fire,” said Tom Giambelluca, retired ¶«¾«Ó°Òµ ²ÑÄå²Ô´Ç²¹ professor of Geography and Environment, former director of the WRRC, and leader of the Hawaiʻi Mesonet. “With real-time data on factors like soil moisture, we can better identify areas at high risk for wildfires or flooding.”

Utilizing a well distributed network of weather stations is crucial in Hawaiʻi, where diverse landscapes create extreme climate variability. In West Maui, annual rainfall can differ by more than 140 inches within a mile, highlighting the need for precise, localized data.

“The Hawaiʻi Mesonet is adding high quality weather observations in places where they are most needed,” Giambelluca said.

“This mapping system is a game-changer for wildfire preparedness in Hawaiʻi,” said Clay Trauernicht, assistant specialist in the ¶«¾«Ó°Òµ ²ÑÄå²Ô´Ç²¹ . “Using current data allows us to better anticipate fire risks and take proactive measures to protect communities.”

The Hawaiʻi Emergency Management Agency, Federal Emergency Management Agency and Hawaiʻi State Legislature provided funding to create the fire ignition probability maps.

Bateni, Giambelluca, Trauernicht and Pacific Islands Climate Adaptation Science Center University Consortium Director Ryan Longman will host a presentation in person and online on April 1 at noon to explain how the maps were created, how they predict fire risk and how to access and use the data.

• Note: To view the most current maps, visit the Hawaiʻi Climate Data Portal website, click on “visualize data,” then “ignition probability” to select the dataset you would like to view and then click submit at the bottom.

The University of Hawaiʻi at ²ÑÄå²Ô´Ç²¹ hosted the from March 15 to 23, bringing together 32 students and 19 instructors from 16 countries. The program provided an immersive learning experience focused on El Niño-Southern Oscillation (ENSO), a climate pattern that influences global weather.

This year marks the 50th anniversary of key milestones in ENSO research, including the work of Klaus Wyrtki, the late renowned oceanographer from ¶«¾«Ó°Òµ ²ÑÄå²Ô´Ç²¹. His groundbreaking studies helped shape modern understanding of El Niño and its impacts on weather patterns worldwide.

• Related ¶«¾«Ó°Òµ News story: Hawaiʻi State Legislature honors late oceanographer Klaus Wyrtki, March 19, 2025

Over the nine-day program, participants engaged in morning lectures covering ENSO fundamentals, followed by student-led discussions on influential scientific papers. Afternoons featured student presentations, hands-on training and collaborative research projects. The curriculum provided participants a more thorough look at ENSO through real-world data analysis, modeling techniques and forecasting methods.

“This year’s ENSO Winter School was an incredible opportunity for students to engage directly with leading researchers and gain hands-on experience in ENSO science,” said Christina Karamperidou, chair of the school’s scientific organizing committee, and professor and associate department chair in ¶«¾«Ó°Òµ ²ÑÄå²Ô´Ç²¹â€™s . “Seeing participants from around the world collaborate and deepen their understanding of climate variability was truly inspiring. By hosting this vibrant community of scientists and future research leaders, the University of Hawaiʻi at ²ÑÄå²Ô´Ç²¹ reinforces its reputation as a central hub for cutting-edge ENSO research.”

“Participating in the ENSO Winter School has not only deepened my understanding of the El Niño-Southern Oscillation but also broadened my perspective on nature and its dynamics, as well as strengthened my professional network,” said Roger Manay-Torres from the Instituto Geofísico del Perú. “This experience has been incredibly valuable, both academically and professionally, and it has far exceeded my expectations.”

Regina R. Rodrigues, a professor of physical oceanography at the Federal University of Santa Catarina in Brazil was one of the lecturers, and talked about ENSO’s impacts on weather extremes, etc.

“It was a great experience to spend more than a week with students, earlier career researchers and many of the most prominent experts on ENSO,” Rodrigues said. “I learned more about past ENSO from paleoclimate records and about future ENSO from climate projections.”

Jérôme Vialard, a senior scientist at Institut de Recherche pour le Développement in Paris, added, “I have worked on ENSO for almost 30 years, but found the lectures of other instructors useful. Some refreshed my memory, and some taught me new things on topics I know less about, such as paleo-climate or machine learning.”

The school was supported by ¶«¾«Ó°Òµ ²ÑÄå²Ô´Ç²¹â€™s , International and U.S. CLIVAR, IAPSO/IUGG, CIMAR and the Inter-American Institute for Global Change Research.

Some parts of Hawaiʻi are sinking faster than others. That discovery, by researchers at the University of Hawaiʻi at ²ÑÄå²Ô´Ç²¹, also highlights that as sea level rises, the infrastructure, businesses and communities in these low-lying areas are at risk of flooding sooner than scientists anticipated, particularly in certain urban areas of Oʻahu.

“Our findings highlight that subsidence (gradual caving in or sinking of an area of land) 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 (CRC) at the ¶«¾«Ó°Òµ ²ÑÄå²Ô´Ç²¹ (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.”

Localized sinking

As islands in Hawaiʻi move farther from the hotspot beneath Hawaiʻi Island, they very slowly sink due to their own weight. This island-wide subsidence rate is low on Oʻahu, around 0.6 millimeters, about the thickness of 10 sheets of printer paper, each year. However, the researchers found localized areas on the south shore of Oʻahu where land is sinking nearly 40 times faster, exceeding 25 millimeters per year. The rate and localized nature of the sinking surprised the research team.

“Much of the urban development and infrastructure, including parts of the industrial Mapunapuna area, is built on sediments and artificial fill,” said Murray. “We think the majority of subsidence is related to the compaction of these materials over time.”

Murray and co-authors analyzed nearly two decades of satellite radar data to measure vertical land motion across the Hawaiian Islands. They also developed a high-resolution digital elevation model to accurately map coastal topography. By combining these datasets, they modeled how sea level rise and ongoing subsidence will exacerbate future flooding.

“In places like the Mapunapuna industrial region, subsidence could increase flood exposure area by over 50% by 2050.” — Phil Thompson

“This rate of land subsidence is faster than the long-term rate of sea level rise in Hawaiʻi (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 ¶«¾«Ó°Òµ 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.”

The shoreline plays a vital role in sustaining Hawaiʻi’s coastal communities, economy and infrastructure. The researchers found that sinking rates of certain coastal regions have remained consistent over the past two decades, suggesting that subsidence will persistently exacerbate flooding for parts of the island. If subsidence is not accounted for, urban planning and coastal adaptation strategies may underestimate the urgency of mitigation efforts.

“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 Hawaiʻi by ensuring that local adaptation strategies are based on the best available science, ultimately helping to protect homes, businesses, and cultural areas.”

—By Marcie Grabowski