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The Impact of Sea-Level Rise and Climate Change on Pacific Ocean Atolls Completed

By Pacific Coastal and Marine Science Center June 27, 2022

Providing basic understanding and specific information on storm-wave inundation of atoll islands that house Department of Defense installations, and assessing the resulting impact of sea-level rise and storm-wave inundation on infrastructure and freshwater availability under a variety of sea-level rise and climatic scenarios.

Background

Waves overtop the beach on the north side of Roi-Namur Island and water runs into the nearby street.

Learn about project background, objectives, and approach

Background

Publications

USGS Publications spread out on a table

Access our publications on topics relating to this study. See the Data page for links to all published data.

Publications

News

 Waves wash over a road on along island beach. Palm trees in background.

Read news about our research on Kwajalein, 2014-2018

News

Roi-Namur Island on Kwajalein Atoll serves as our test case

Visit the research overview web site for more information.

The Problem

Many U.S. Pacific islands are atolls fringed with coral reefs and have maximum elevations of 3–5 meters, with mean elevations of 1–2 meters. Sea level in the western Pacific Ocean has been increasing at a rate 2–3 times the global average, resulting in almost 0.3 meters of net rise since 1990. The 2012 US National Climate Assessment provided global sea level rise scenarios that ranged from 0.2 to 2.0 meters by 2100. Regional scenarios are needed. A high surf event in December 2008 overwashed numerous atolls in Micronesia, ruining freshwater supplies and destroying agriculture on approximately 60% of the inhabited islands. Sea-level rise will exacerbate the hazards posed by climate change (storms, waves, temperatures, precipitation, etc.) to infrastructure, freshwater supplies, agriculture, and habitats for threatened and endangered species on U.S. and U.S.-affiliated atoll islands.

Project Objectives

  1. Provide basic understanding and specific information on storm-wave-induced overwash and inundation of atoll islands that house Department of Defense (DoD) installations.
  2. Assess the resulting impact of sea-level rise and storm-wave inundation on infrastructure and freshwater availability under a variety of sea-level rise and climatic scenarios.
  3. Use Roi-Namur Island (Reagan Test Site–U.S. Army Kwajalein Atoll) on Kwajalein Atoll in the Republic of the Marshall Islands (U.S. Associated Pacific Islands) as a test case based on historical information, sea-level rise predictions, and global climate model (GCM) output.

Below are other science projects associated with this project.

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High coastal arctic bluff with broken chunks, some that are ready to fall into the crashing waves, and some that have fallen.

Coastal Climate Impacts

The impacts of climate change and sea-level rise around the Pacific and Arctic Oceans can vary tremendously. Thus far the vast majority of national and international impact assessments and models of coastal climate change have focused on low-relief coastlines that are not near seismically active zones. Furthermore, the degree to which extreme waves and wind will add further stress to coastal...
By
Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center
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Coastal Climate Impacts

The impacts of climate change and sea-level rise around the Pacific and Arctic Oceans can vary tremendously. Thus far the vast majority of national and international impact assessments and models of coastal climate change have focused on low-relief coastlines that are not near seismically active zones. Furthermore, the degree to which extreme waves and wind will add further stress to coastal...
Learn More
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Coral head that looks like lettuce sits on sandy bottom in clear blue water and is surrounded by brightly colored fish.

Coral Reef Project

Explore the fascinating undersea world of coral reefs. Learn how we map, monitor, and model coral reefs so we can better understand, protect, and preserve our Nation's reefs.
By
Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center
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Coral Reef Project

Explore the fascinating undersea world of coral reefs. Learn how we map, monitor, and model coral reefs so we can better understand, protect, and preserve our Nation's reefs.
Learn More
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Aerial photograph of Wake Island. The deep ocean water around the atoll is dark blue, the shallow lagoon water is light blue.

Low-lying areas of tropical Pacific islands

Sea level is rising faster than projected in the western Pacific, so understanding how wave-driven coastal flooding will affect inhabited, low-lying islands—most notably, the familiar ring-shaped atolls—as well as the low-elevation areas of high islands in the Pacific Ocean, is critical for decision-makers in protecting infrastructure or relocating resources and people.
By
Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center
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Low-lying areas of tropical Pacific islands

Sea level is rising faster than projected in the western Pacific, so understanding how wave-driven coastal flooding will affect inhabited, low-lying islands—most notably, the familiar ring-shaped atolls—as well as the low-elevation areas of high islands in the Pacific Ocean, is critical for decision-makers in protecting infrastructure or relocating resources and people.
Learn More
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Image: Coral reefs, Kwajalein Atoll, Republic of the Marshall Islands

Coral Reef Project: Kwajalein Island

The USGS is working to provide a better understanding of how spatially-varying atoll morphology and coral cover interact with changes in water level to affect the propagation of waves of different heights and wavelengths across atoll reefs.
By
Pacific Coastal and Marine Science Center
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Coral Reef Project: Kwajalein Island

The USGS is working to provide a better understanding of how spatially-varying atoll morphology and coral cover interact with changes in water level to affect the propagation of waves of different heights and wavelengths across atoll reefs.
Learn More
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lone road lined by palm trees on a small flat island, with water from the sea washing over the road

Coral Reef Project: Roi-Namur Island

The USGS is working to provide a better understanding of how spatially-varying atoll morphology and coral cover interact with changes in water level to affect the propagation of waves of different heights and wavelengths across atoll reefs.
By
Pacific Coastal and Marine Science Center
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Coral Reef Project: Roi-Namur Island

The USGS is working to provide a better understanding of how spatially-varying atoll morphology and coral cover interact with changes in water level to affect the propagation of waves of different heights and wavelengths across atoll reefs.
Learn More

Below are data or web applications associated with this project.

Model parameter input files to compare the influence of channels in fringing coral reefs on alongshore variations in wave-driven runup along the shoreline

An extensive set of physics-based XBeach Non-hydrostatic hydrodynamic model simulations (with input files here included) were used to evaluate the influence of shore-normal reef channels on flooding along fringing reef-lined coasts, specifically during extreme wave conditions when the risk for coastal flooding and the resulting impact to coastal communities is greatest. These input files accompany
By
Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Model parameter input files to compare locations of coral reef restoration on different reef profiles to reduce coastal flooding

This dataset consists of physics-based XBeach Non-hydrostatic hydrodynamic models input files used to study how coral reef restoration affects waves and wave-driven water levels over coral reefs, and the resulting wave-driven runup on the adjacent shoreline. Coral reefs are effective natural coastal flood barriers that protect adjacent communities. Coral degradation compromises the coastal protect
By
Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Cross-reef wave and water level data from coral reef environments

Coral reefs provide important protection for tropical coastlines against the impact of large waves and storm damage by energy dissipation through wave breaking and bottom friction. However, climate change and sea level rise have led to growing concern for how the hydrodynamics across these reefs will evolve and whether these changes will leave tropical coastlines more vulnerable to large wave even
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Database to model three-dimensional flow over coral reef spur-and-groove morphology

This data set consists of physics-based Delft3D-FLOW and SWAN hydrodynamic models input files used to study the wave-induced 3D flow over spur-and-groove (SAG) formations. SAG are a common and impressive characteristic of coral reefs. They are composed of a series of submerged shore-normal coral ridges (spurs) separated by shore-normal patches of sediment (grooves) on the fore reef of coral reef e
By
Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Coral reef profiles for wave-runup prediction

This data release includes representative cluster profiles (RCPs) from a large (>24,000) selection of coral reef topobathymetric cross-shore profiles (Scott and others, 2020). We used statistics, machine learning, and numerical modelling to develop the set of RCPs, which can be used to accurately represent the shoreline hydrodynamics of a large variety of coral reef-lined coasts around the globe.
By
Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Model parameter input files to compare wave-averaged versus wave-resolving XBeach coastal flooding models for coral reef-lined coasts

This data release includes the XBeach input data files used to evaluate the importance of explicitly modeling sea-swell waves for runup. This was examined using a 2D XBeach short wave-averaged (surfbeat, XB-SB) and a wave-resolving (non-hydrostatic, XB-NH) model of Roi-Namur Island on Kwajalein Atoll in the Republic of Marshall Islands. Results show that explicitly modelling the sea-swell componen
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Physics-based numerical model simulations of wave propagation over and around theoretical atoll and island morphologies for sea-level rise scenarios

Schematic atoll models with varying theoretical morphologies were used to evaluate the relative control of individual morphological parameters on alongshore transport gradients. Here we present physics-based numerical SWAN model results of incident wave transformations for a range of atoll and island morphologies and sea-level rise scenarios. Model results are presented in NetCDF format, accompani
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Below are multimedia items associated with this project.

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Below are publications associated with this project.

Filter Total Items: 32

A numerical study of geomorphic and oceanographic controls on wave-driven runup on fringing reefs with shore-normal channels

Many populated, tropical coastlines fronted by fringing coral reefs are exposed to wave-driven marine flooding that is exacerbated by sea-level rise. Most fringing coral reef are not alongshore uniform, but bisected by shore-normal channels; however, little is known about the influence of such channels on alongshore variations on runup and flooding of the adjacent coastline. We con-ducted a parame
Authors
Curt D. Storlazzi, Annouk Rey, Ap van Dongeren
By
Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Spectral wave-driven bedload transport across a coral reef flat/lagoon complex

Coral reefs are an important source of sediment for reef-lined coasts by helping to maintain beaches while also providing protection in the form of wave energy dissipation. Understanding the mechanisms by which sediment is delivered to the coast as well as better constraining the total volumes generated are critical for projecting future coastal change. A month-long hydrodynamics and sediment tran
Authors
Kurt J. Rosenberger, Curt D. Storlazzi, Olivia Cheriton, Andrew Pomeroy, Jeff E. Hansen, Ryan Lowe, Mark Buckley
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Modeling three-dimensional flow over spur-and-groove morphology

Spur-and-groove (SAG) morphology characterizes the fore reef of many coral reefs worldwide. Although the existence and geometrical properties of SAG have been well documented, an understanding of the hydrodynamics over them is limited. Here, the three-dimensional flow patterns over SAG formations, and a sensitivity of those patterns to waves, currents, and SAG geometry were characterized using the
Authors
Renan da Silva, Curt D. Storlazzi, Justin S. Rogers, Johan Reyns, Robert T. McCall
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

The impacts of a changing climate to DOD coastal facilities in the tropical Pacific Ocean

The USGS, the National Oceanic and Atmospheric Administration (NOAA), Deltares, and the University of Hawaii (UH) recently completed a study investigating the impact of a changing climate and sea-level rise on Roi-Namur Island on Kwajalein Atoll in the Republic of the Marshall Islands, which is part of the Ronald Reagan Ballistic Missile Defense Test Site (RTS). The isolated location of RTS makes
Authors
Curt D. Storlazzi
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Sea‐level rise will drive divergent sediment transport patterns on fore reefs and reef flats, potentially causing erosion on atoll islands

Atoll reef islands primarily consist of unconsolidated sediment, and their ocean‐facing shorelines are maintained by sediment produced and transported across their reefs. Changes in incident waves can alter cross‐shore sediment exchange and, thus, affect the sediment budget and morphology of atoll reef islands. Here we investigate the influence of sea level rise and projected wave climate change o
Authors
James F Bramante, Andrew D Ashton, Curt D. Storlazzi, Olivia Cheriton, Jeffrey P. Donnelly
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

The importance of explicitly modelling sea-swell waves for runup on reef-lined coasts

The importance of explicitly modelling sea-swell waves for runup was examined using a 2D XBeach short wave-averaged (surfbeat, “XB-SB”) and a wave-resolving (non-hydrostatic, “XB-NH”) model of Roi-Namur Island on Kwajalein Atoll in the Republic of Marshall Islands. Field observations on water levels, wave heights, and wave runup were used to drive and evaluate both models, which were subsequently
Authors
Ellen Quataert, Curt D. Storlazzi, Ap van Dongeren, Robert T. McCall
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

In situ observations of wave transformation and infragravity bore development across reef flats of varying geomorphology

The character and energetics of infragravity (IG, 25 s < period < 250 s) and very-low frequency (VLF, period > 250 s) waves over coral reef flats can enhance shoreline erosion or accretion, and also govern extreme shoreline events such as runup, overwash, and flooding on coral reef-lined coasts. Here we use in situ wave measurements collected along cross-reef transects at 7 sites on Pacific island
Authors
Olivia Cheriton, Curt D. Storlazzi, Kurt J. Rosenberger
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Hydro-morphological characterization of coral reefs for wave runup prediction

Many coral reef-lined coasts are low-lying with elevations 30,000) dataset of measured coral reef topobathymetric cross-shore profiles, statistics, machine learning, and numerical modeling to develop a set of representative cluster profiles (RCPs) that can be used to accurately represent the shoreline hydrodynamics of a large variety of coral reef-lined coasts around the globe. In two stages, the
Authors
Fred Scott, Jose A. A. Antolinez, Robert T. McCall, Curt D. Storlazzi, Ad Reiners, Stuart Pearson
By
Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Steps to develop early warning systems and future scenarios of wave-driven flooding along coral reef-lined coasts

Tropical coral reef-lined coasts are exposed to storm wave-driven flooding. In the future, flood events during storms are expected to occur more frequently and to be more severe due to sea-level rise, changes in wind and weather patterns, and the deterioration of coral reefs. Hence, disaster managers and coastal planners are in urgent need of decision-support tools. In the short-term, these tools
Authors
Gundula Winter, Curt D. Storlazzi, Sean Vitousek, Ap van Dongeren, Robert T. McCall, Ron Hoeke, William Skirving, John Marra, Johan Reyns, Jerome Aucan, Matthew J. Widlansky, Janet Becker, Chris Perry, Gerd Masselink, Ryan Lowe, Murray Ford, Andrew Pomeroy, Fernando J. Mendez, Ana C. Rueda, Moritz Wandres
By
Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Assessing morphologic controls on atoll island alongshore sediment transport gradients due to future sea-level rise

Atoll islands’ alongshore sediment transport gradients depend on how island and reef morphology affect incident wave energy. It is unclear, though, how potential atoll morphologic configurations influence shoreline erosion and/or accretion patterns, and how these relationships will respond to future sea-level rise (SLR). Schematic atoll models with varying morphologies were used to evaluate the re
Authors
James B. Shope, Curt D. Storlazzi
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

HyCReWW: A hybrid coral reef wave and water level metamodel

Wave-induced flooding is a major coastal hazard on tropical islands fronted by coral reefs. The variability of shape, size, and physical characteristics of the reefs across the globe make it difficult to obtain a parameterization of wave run-up, which is needed for risk assessments. Therefore, we developed the HyCReWW metamodel to predict wave run-up under a wide range of reef morphometric and off
Authors
Ana C. Rueda, Laura Cagigal, Stuart Pearson, Jose Antolínez, Curt D. Storlazzi, Ap van Dongeren, Paula Camus, Fernando J. Mendez
By
Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Physical mechanisms influencing localized patterns of temperature variability and coral bleaching within a system of reef atolls

Interactions between oceanic and atmospheric processes within coral reefs can significantly alter local-scale ( 60%) over most of this system; however, the bleaching patterns were not uniform. Little is known about the processes governing thermodynamic variability within atolls, particularly those that are dominated by large amplitude tides. Here, we identify three mechanisms at Scott Reef that al
Authors
Rebecca H. Green, Ryan J. Lowe, Mark L. Buckley, Taryn M. Lopez, James Gilmour
By
St. Petersburg Coastal and Marine Science Center, Pacific Coastal and Marine Science Center

Below are news stories associated with this project.

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Image: Coral reefs, Kwajalein Atoll, Republic of the Marshall Islands

News about the impact of sea-level rise and climate change on Pacific Ocean atolls, 2014-2018

News from 2014-2018

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Pacific Coastal and Marine Science Center
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Many Low-Lying Atoll Islands Will Be Uninhabitable by Mid-21st Century

Sea-level rise and wave-driven flooding will negatively impact freshwater resources on many low-lying atoll islands in such a way that many could be...

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Saltwater contamination of freshwater resources could make many atoll islands uninhabitable in decades

Sea-level rise and wave-driven flooding could introduce saltwater so frequently into atoll islands’ freshwater resources that many will be...

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Documentary about sea-level rise threatening the Republic of the Marshall Islands features USGS findings

USGS research in the Republic of the Marshall Islands forms part of the scientific foundation of an interactive documentary released April 6 by PBS...

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Pacific Missile Tracking Site Could Be Unusable in 20 Years Due to Climate Change

Living and working on the Pacific islands hosting a key missile tracking site soon could be almost impossible due to the impacts of climate change.

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International workshop on “Understanding Flooding on Reef-lined Island Coastlines”

USGS research geologist Curt Storlazzi led a workshop on “Understanding Flooding on Reef-lined Island Coastlines” (UFORIC) in Honolulu, Hawaiʻi, from...

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USGS coastal-flooding projections inform national defense authorization act

Results of USGS research investigating sea-level rise impacts to Department of Defense (DoD) facilities in Pacific atolls are included in the National...

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USGS geologist chairs discussion of issues facing Department of Defense installations in the Pacific and Arctic

At the request of the U.S. Department of Defense (DoD) Strategic Environmental Research and Development Program (SERDP), USGS geologist Curt Storlazzi...

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