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Pacific Coastal and Marine Science Center

USGS Pacific Coral Reefs

Photo of coral reef.  

Kwajalein Island, Kwajalein Atoll, Republic of the Marshall Islands

Satellite image of the island of Guam.

WorldView2 satellite image of Kwajalein Island

Overview

Kwajalein Island is the southernmost and largest island on Kwajalein Atoll, the largest coral atoll in the world, in the Republic of the Marshall Islands, which is a self-governed and freely associated republic with the United States. The atoll lies near the equator about 3,900 km (2,100 mi) southwest of Hawaiʻi, and is comprised of 97 islands and islets. Known locally as “Kwaj,” the island encompasses a total area of about 3.1 sq km (about 1.2 sq mi). Kwajalein, and several other islands on the atoll (including Roi-Namur), is leased by the United States as part of the U.S. Army Kwajalein Atoll, which is, in turn, part of the Ronald Reagan Ballistic Missile Defense Test Site, formerly known as the Kwajalein Missile Range.

Motivation

Observations show that sea level is rising globally at a rate almost double the Intergovernmental Panel for Climate Change’s 2007 report, and up to half and order of magnitude greater in the central and western Pacific Ocean. Recent estimates suggest sea level will exceed 1.0 m, and may reach 2.0 m, above 2000 levels by the end of the 21st century. Sea-level rise is particularly critical for unconsolidated low-lying coral atoll islands, many of which have maximum elevations of less than 4 m above present sea level, such as Kwajalein. These islands support 2000+ year-old cultures, yet the amount of land and water available for human habitation, water and food sources, and ecosystems is limited and extremely vulnerable to marine inundation from sea-level rise. Vertical coral reef flat accretion rates for coral reefs exposed to open-ocean storm waves (1 to 4 mm/yr) are up to an order of magnitude smaller than the rates of sea-level rise projected for the years 2000–2100 (8 to 16 mm/yr), therefore projected sea-level rise will outstrip potential new reef flat accretion, resulting in a net increase in water depth over exposed coral reef flats on the order of 0.4 to 1.5 m during the 21st century. The extreme vulnerability of these communities to changing oceanic and atmospheric conditions represents a serious threat through impacts on food and water security, public safety, and environmental health.

The USGS is working with Deltares, NOAA, and the U.S. Department of Defense 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. Such information is necessary to model how predicted sea-level rise and climate change may alter wave-driven inundation, and thus impacts to infrastructure, agriculture, and natural habitats, on low-lying atoll islands.

For additional information, visit https://walrus.wr.usgs.gov/climate-change/atolls/

Products

Divided by theme (Note: some products are listed multiple times as they cross multiple themes)

Circulation and sediment dynamics

Ferrario, F., Beck, M.W., Storlazzi, C.D., Micheli, F., Shepard, C.C., and Airoldi, L., 2014, The effectiveness of coral reefs for coastal hazard risk reduction and adaptation: Nature Communications, 5:3794, doi:10.1038/ncomms4794. [download PDF]

Rogers, J.S., Monismith, S.G., Feddersen, F., and Storlazzi, C.D., 2013, Hydrodynamics of spur and groove formations on a coral reef: Journal of Geophysical Research—Oceans, v. 118, p. 3,059-3,073, doi:10.1002/jgrc.20225.

Grady, A. E., Moore, L. J., Storlazzi, C. D., Elias, E., and Reidenbach, M. A., 2013, The influence of sea level rise and changes in fringing reef morphology on gradients in alongshore sediment transport: Geophysical Research Letters, v. 40, i. 12, p. 3096–3101, doi:10.1002/grl.50577.

Storlazzi, C.D., Elias, E., Field, M.E., and Presto, M.K., 2011, Numerical modeling of the impact of sea-level rise on fringing coral reef hydrodynamics and sediment transport: Coral Reefs, v. 30, Supplement 1, p. 83-96, doi:10.1007/s00338-011-0723-9.

U.S. Geological Survey, 2009, Science-based strategies for sustaining coral ecosystems: U.S. Geological Survey Fact Sheet 2009–3089, 4 p.

Climate change

Ferrario, F., Beck, M.W., Storlazzi, C.D., Micheli, F., Shepard, C.C., and Airoldi, L., 2014, The effectiveness of coral reefs for coastal hazard risk reduction and adaptation: Nature Communications, 5:3794, doi:10.1038/ncomms4794 [download PDF]

Grady, A. E., Moore, L. J., Storlazzi, C. D., Elias, E., and Reidenbach, M. A., 2013, The influence of sea level rise and changes in fringing reef morphology on gradients in alongshore sediment transport: Geophysical Research Letters, v. 40, i. 12, p. 3096–3101, doi:10.1002/grl.50577.

Field, M.E., Ogston, A.S., and Storlazzi, C.D., 2011, Rising sea level may cause decline of fringing coral reefs: Eos, v. 92, p. 273-280.

Storlazzi, C.D., Elias, E., Field, M.E., and Presto, M.K., 2011, Numerical modeling of the impact of sea-level rise on fringing coral reef hydrodynamics and sediment transport: Coral Reefs, v. 30, Supplement 1, p. 83-96, doi:10.1007/s00338-011-0723-9.

U.S. Geological Survey, 2009, Science-based strategies for sustaining coral ecosystems: U.S. Geological Survey Fact Sheet 2009–3089, 4 p.

Jokiel, P.L., 2004, Temperature stress and coral bleaching, in Rosenberg, E., and Loya, Y., eds., Coral Health and Disease, Springer-Verlag, Heidelberg, p. 401–425.

Future reefs

Ferrario, F., Beck, M.W., Storlazzi, C.D., Micheli, F., Shepard, C.C., and Airoldi, L., 2014, The effectiveness of coral reefs for coastal hazard risk reduction and adaptation: Nature Communications, 5:3794, doi:10.1038/ncomms4794 [download PDF]

U.S. Geological Survey, 2009, Science-based strategies for sustaining coral ecosystems: U.S. Geological Survey Fact Sheet 2009–3089, 4 p.

Mapping

U.S. Geological Survey, 2009, Science-based strategies for sustaining coral ecosystems: U.S. Geological Survey Fact Sheet 2009–3089, 4 p.

Other selected works

Coral Reefs Provide Critical Coastal Protection

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