[Coral-List] press release: Climate Change Reduces Coral Reefs’ Ability to Protect Coasts

Storlazzi, Curt cstorlazzi at usgs.gov
Thu Jul 30 12:12:50 EDT 2015

Coral reef colleagues,

For a little more background, please find the entire press release below -



*Climate Change Reduces Coral Reefs’ Ability to Protect Coasts*


Coral reefs, under pressure from climate change and direct human activity,
may have a reduced ability to protect tropical islands against wave attack,
erosion and salinization of drinking water resources, which help to sustain
life on those islands. A new paper by researchers from the Dutch
independent institute for applied research Deltares and the U.S. Geological
Survey gives guidance to coastal managers to assess how climate change will
affect a coral reef’s ability to mitigate coastal hazards.

 About 30 million people are dependent on the protection by coral reefs as
they live on low-lying coral islands and atolls. At present, some of these
islands experience flooding due to wave events a few times per decade. It
is expected that this rate of flooding will increase due to sea level rise
and coral reef decay, as the remaining dead corals are generally smoother
in structure, and do less to dissipate wave energy. Loss of coral cover not
only causes increased shoreline erosion but also affects the sparse
drinking water resources on these islands, which may eventually make these
islands uninhabitable.  In order to prevent or mitigate these impacts,
coastal managers need know to what extent their reef system may lose its
protective function so that they can take action. The new study gives
guidance on a local reef’s sensitivity to change. The new research has been
accepted for publication in “Geophysical Research Letters,” a journal of
the American Geophysical Union.

To gain insight into effects of changing conditions on coral reefs, the
study authors used Xbeach, an open-source wave model. The computer model
was first validated using field measurements obtained on the Kwajalein
Atoll in the Marshall Islands in the Pacific Ocean, and was then used to
investigate what the effects on water levels, waves, and wave-driven runup
would be if certain reef properties change. Reef roughness, steepness,
width and the total water level on the reef platform are all important
factors for coastal managers to consider when planning mitigating measures.

The results suggest that coasts fronted by relatively narrow reefs with
steep faces and deeper, smoother reef flats are expected to experience the
highest wave runup and thus potential for island flooding. Wave runup
increases for higher water levels (that are expected with sea level rise),
higher waves, and lower bed roughness (as coral degrades and reefs become
smoother), which are all expected effects of climate change. Rising sea
levels and climate change will have a significant negative impact on the
ability of coral reefs to mitigate the effects of coastal hazards in the

The research paper, “The influence of coral reefs and climate change on
wave-driven flooding of tropical coastlines
is published as an open-access paper and available online.

Quataert, E., C. Storlazzi, A. van Rooijen, O. Cheriton, and A. van
Dongeren (2015), The influence of coral reefs and climate change on
wave-driven flooding of tropical coastlines, Geophysical Research Letters,
42, doi:10.1002/2015GL064861

Additional Photos:

Curt Storlazzi, Ph.D.
U.S. Geological Survey
Pacific Coastal and Marine Science Center
400 Natural Bridges Drive
Santa Cruz, CA 95060
(831) 460-7521 phone
(831) 427-4748 fax

Staff web page:
Pacific Coral Reefs:
*http://coralreefs.wr.usgs.gov/ <http://coralreefs.wr.usgs.gov/>*
Sea-level Rise and Pacific Atolls:

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